Antigens: Substances that are recognized by the immune system and induce an immune reaction.Antigens, Bacterial: Substances elaborated by bacteria that have antigenic activity.Antigens, Neoplasm: Proteins, glycoprotein, or lipoprotein moieties on surfaces of tumor cells that are usually identified by monoclonal antibodies. Many of these are of either embryonic or viral origin.Antigens, Surface: Antigens on surfaces of cells, including infectious or foreign cells or viruses. They are usually protein-containing groups on cell membranes or walls and may be isolated.Antigens, Viral: Substances elaborated by viruses that have antigenic activity.Antigens, Protozoan: Any part or derivative of any protozoan that elicits immunity; malaria (Plasmodium) and trypanosome antigens are presently the most frequently encountered.Antigens, Polyomavirus Transforming: Polyomavirus antigens which cause infection and cellular transformation. The large T antigen is necessary for the initiation of viral DNA synthesis, repression of transcription of the early region and is responsible in conjunction with the middle T antigen for the transformation of primary cells. Small T antigen is necessary for the completion of the productive infection cycle.HLA Antigens: Antigens determined by leukocyte loci found on chromosome 6, the major histocompatibility loci in humans. They are polypeptides or glycoproteins found on most nucleated cells and platelets, determine tissue types for transplantation, and are associated with certain diseases.Antigens, Fungal: Substances of fungal origin that have antigenic activity.Antigens, CD: Differentiation antigens residing on mammalian leukocytes. CD stands for cluster of differentiation, which refers to groups of monoclonal antibodies that show similar reactivity with certain subpopulations of antigens of a particular lineage or differentiation stage. The subpopulations of antigens are also known by the same CD designation.Antigens, Helminth: Any part or derivative of a helminth that elicits an immune reaction. The most commonly seen helminth antigens are those of the schistosomes.H-2 Antigens: The major group of transplantation antigens in the mouse.Carcinoembryonic Antigen: A glycoprotein that is secreted into the luminal surface of the epithelia in the gastrointestinal tract. It is found in the feces and pancreaticobiliary secretions and is used to monitor the response to colon cancer treatment.Antigens, Viral, Tumor: Those proteins recognized by antibodies from serum of animals bearing tumors induced by viruses; these proteins are presumably coded for by the nucleic acids of the same viruses that caused the neoplastic transformation.HLA-DR Antigens: A subclass of HLA-D antigens that consist of alpha and beta chains. The inheritance of HLA-DR antigens differs from that of the HLA-DQ ANTIGENS and HLA-DP ANTIGENS.Receptors, Antigen, T-Cell: Molecules on the surface of T-lymphocytes that recognize and combine with antigens. The receptors are non-covalently associated with a complex of several polypeptides collectively called CD3 antigens (ANTIGENS, CD3). Recognition of foreign antigen and the major histocompatibility complex is accomplished by a single heterodimeric antigen-receptor structure, composed of either alpha-beta (RECEPTORS, ANTIGEN, T-CELL, ALPHA-BETA) or gamma-delta (RECEPTORS, ANTIGEN, T-CELL, GAMMA-DELTA) chains.Histocompatibility Antigens: A group of antigens that includes both the major and minor histocompatibility antigens. The former are genetically determined by the major histocompatibility complex. They determine tissue type for transplantation and cause allograft rejections. The latter are systems of allelic alloantigens that can cause weak transplant rejection.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Proliferating Cell Nuclear Antigen: Nuclear antigen with a role in DNA synthesis, DNA repair, and cell cycle progression. PCNA is required for the coordinated synthesis of both leading and lagging strands at the replication fork during DNA replication. PCNA expression correlates with the proliferation activity of several malignant and non-malignant cell types.Histocompatibility Antigens Class II: Large, transmembrane, non-covalently linked glycoproteins (alpha and beta). Both chains can be polymorphic although there is more structural variation in the beta chains. The class II antigens in humans are called HLA-D ANTIGENS and are coded by a gene on chromosome 6. In mice, two genes named IA and IE on chromosome 17 code for the H-2 antigens. The antigens are found on B-lymphocytes, macrophages, epidermal cells, and sperm and are thought to mediate the competence of and cellular cooperation in the immune response. The term IA antigens used to refer only to the proteins encoded by the IA genes in the mouse, but is now used as a generic term for any class II histocompatibility antigen.Prostate-Specific Antigen: A glycoprotein that is a kallikrein-like serine proteinase and an esterase, produced by epithelial cells of both normal and malignant prostate tissue. It is an important marker for the diagnosis of prostate cancer.O Antigens: The lipopolysaccharide-protein somatic antigens, usually from gram-negative bacteria, important in the serological classification of enteric bacilli. The O-specific chains determine the specificity of the O antigens of a given serotype. O antigens are the immunodominant part of the lipopolysaccharide molecule in the intact bacterial cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Receptors, Antigen, B-Cell: IMMUNOGLOBULINS on the surface of B-LYMPHOCYTES. Their MESSENGER RNA contains an EXON with a membrane spanning sequence, producing immunoglobulins in the form of type I transmembrane proteins as opposed to secreted immunoglobulins (ANTIBODIES) which do not contain the membrane spanning segment.Epitopes: Sites on an antigen that interact with specific antibodies.Antigens, CD15: A trisaccharide antigen expressed on glycolipids and many cell-surface glycoproteins. In the blood the antigen is found on the surface of NEUTROPHILS; EOSINOPHILS; and MONOCYTES. In addition, CD15 antigen is a stage-specific embryonic antigen.Antigens, Tumor-Associated, Carbohydrate: Carbohydrate antigens expressed by malignant tissue. They are useful as tumor markers and are measured in the serum by means of a radioimmunoassay employing monoclonal antibodies.HLA-A2 Antigen: A specific HLA-A surface antigen subtype. Members of this subtype contain alpha chains that are encoded by the HLA-A*02 allele family.Antigens, CD8: Differentiation antigens found on thymocytes and on cytotoxic and suppressor T-lymphocytes. CD8 antigens are members of the immunoglobulin supergene family and are associative recognition elements in MHC (Major Histocompatibility Complex) Class I-restricted interactions.T-Lymphocytes: Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.Enzyme-Linked Immunosorbent Assay: An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed.Immunoglobulin G: The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.Blood Group Antigens: Sets of cell surface antigens located on BLOOD CELLS. They are usually membrane GLYCOPROTEINS or GLYCOLIPIDS that are antigenically distinguished by their carbohydrate moieties.Hepatitis B Surface Antigens: Those hepatitis B antigens found on the surface of the Dane particle and on the 20 nm spherical and tubular particles. Several subspecificities of the surface antigen are known. These were formerly called the Australia antigen.Antigens, CD3: Complex of at least five membrane-bound polypeptides in mature T-lymphocytes that are non-covalently associated with one another and with the T-cell receptor (RECEPTORS, ANTIGEN, T-CELL). The CD3 complex includes the gamma, delta, epsilon, zeta, and eta chains (subunits). When antigen binds to the T-cell receptor, the CD3 complex transduces the activating signals to the cytoplasm of the T-cell. The CD3 gamma and delta chains (subunits) are separate from and not related to the gamma/delta chains of the T-cell receptor (RECEPTORS, ANTIGEN, T-CELL, GAMMA-DELTA).Cross Reactions: Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.HLA-A Antigens: Polymorphic class I human histocompatibility (HLA) surface antigens present on almost all nucleated cells. At least 20 antigens have been identified which are encoded by the A locus of multiple alleles on chromosome 6. They serve as targets for T-cell cytolytic responses and are involved with acceptance or rejection of tissue/organ grafts.Histocompatibility Antigens Class I: Membrane glycoproteins consisting of an alpha subunit and a BETA 2-MICROGLOBULIN beta subunit. In humans, highly polymorphic genes on CHROMOSOME 6 encode the alpha subunits of class I antigens and play an important role in determining the serological specificity of the surface antigen. Class I antigens are found on most nucleated cells and are generally detected by their reactivity with alloantisera. These antigens are recognized during GRAFT REJECTION and restrict cell-mediated lysis of virus-infected cells.Mice, Inbred BALB CLymphocyte Activation: Morphologic alteration of small B LYMPHOCYTES or T LYMPHOCYTES in culture into large blast-like cells able to synthesize DNA and RNA and to divide mitotically. It is induced by INTERLEUKINS; MITOGENS such as PHYTOHEMAGGLUTININS, and by specific ANTIGENS. It may also occur in vivo as in GRAFT REJECTION.HLA-D Antigens: Human immune-response or Class II antigens found mainly, but not exclusively, on B-lymphocytes and produced from genes of the HLA-D locus. They are extremely polymorphic families of glycopeptides, each consisting of two chains, alpha and beta. This group of antigens includes the -DR, -DQ and -DP designations, of which HLA-DR is most studied; some of these glycoproteins are associated with certain diseases, possibly of immune etiology.Antibody Specificity: The property of antibodies which enables them to react with some ANTIGENIC DETERMINANTS and not with others. Specificity is dependent on chemical composition, physical forces, and molecular structure at the binding site.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Receptors, Antigen: Molecules on the surface of B- and T-lymphocytes that recognize and combine with specific antigens.Antigens, CD45: High-molecular weight glycoproteins uniquely expressed on the surface of LEUKOCYTES and their hemopoietic progenitors. They contain a cytoplasmic protein tyrosine phosphatase activity which plays a role in intracellular signaling from the CELL SURFACE RECEPTORS. The CD45 antigens occur as multiple isoforms that result from alternative mRNA splicing and differential usage of three exons.Hepatitis B Antigens: Antigens of the virion of the HEPATITIS B VIRUS or the Dane particle, its surface (HEPATITIS B SURFACE ANTIGENS), core (HEPATITIS B CORE ANTIGENS), and other associated antigens, including the HEPATITIS B E ANTIGENS.Antigens, CD4: 55-kDa antigens found on HELPER-INDUCER T-LYMPHOCYTES and on a variety of other immune cell types. CD4 antigens are members of the immunoglobulin supergene family and are implicated as associative recognition elements in MAJOR HISTOCOMPATIBILITY COMPLEX class II-restricted immune responses. On T-lymphocytes they define the helper/inducer subset. CD4 antigens also serve as INTERLEUKIN-15 receptors and bind to the HIV receptors, binding directly to the HIV ENVELOPE PROTEIN GP120.Antigen-Antibody Reactions: The processes triggered by interactions of ANTIBODIES with their ANTIGENS.Antigens, CD1: Glycoproteins expressed on cortical thymocytes and on some dendritic cells and B-cells. Their structure is similar to that of MHC Class I and their function has been postulated as similar also. CD1 antigens are highly specific markers for human LANGERHANS CELLS.Fluorescent Antibody Technique: Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.Antibodies, Bacterial: Immunoglobulins produced in a response to BACTERIAL ANTIGENS.Immune Sera: Serum that contains antibodies. It is obtained from an animal that has been immunized either by ANTIGEN injection or infection with microorganisms containing the antigen.Antibody Formation: The production of ANTIBODIES by proliferating and differentiated B-LYMPHOCYTES under stimulation by ANTIGENS.HLA-B Antigens: Class I human histocompatibility (HLA) surface antigens encoded by more than 30 detectable alleles on locus B of the HLA complex, the most polymorphic of all the HLA specificities. Several of these antigens (e.g., HLA-B27, -B7, -B8) are strongly associated with predisposition to rheumatoid and other autoimmune disorders. Like other class I HLA determinants, they are involved in the cellular immune reactivity of cytolytic T lymphocytes.Antigens, Differentiation: Antigens expressed primarily on the membranes of living cells during sequential stages of maturation and differentiation. As immunologic markers they have high organ and tissue specificity and are useful as probes in studies of normal cell development as well as neoplastic transformation.Immunization: Deliberate stimulation of the host's immune response. ACTIVE IMMUNIZATION involves administration of ANTIGENS or IMMUNOLOGIC ADJUVANTS. PASSIVE IMMUNIZATION involves administration of IMMUNE SERA or LYMPHOCYTES or their extracts (e.g., transfer factor, immune RNA) or transplantation of immunocompetent cell producing tissue (thymus or bone marrow).Cell Line: Established cell cultures that have the potential to propagate indefinitely.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.B-Lymphocytes: Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation.MART-1 Antigen: A melanosome-specific protein that plays a role in the expression, stability, trafficking, and processing of GP100 MELANOMA ANTIGEN, which is critical to the formation of Stage II MELANOSOMES. The protein is used as an antigen marker for MELANOMA cells.HIV Antigens: Antigens associated with specific proteins of the human adult T-cell immunodeficiency virus (HIV); also called HTLV-III-associated and lymphadenopathy-associated virus (LAV) antigens.Antigens, CD80: A costimulatory ligand expressed by ANTIGEN-PRESENTING CELLS that binds to CTLA-4 ANTIGEN with high specificity and to CD28 ANTIGEN with low specificity. The interaction of CD80 with CD28 ANTIGEN provides a costimulatory signal to T-LYMPHOCYTES, while its interaction with CTLA-4 ANTIGEN may play a role in inducing PERIPHERAL TOLERANCE.Epstein-Barr Virus Nuclear Antigens: Nuclear antigens encoded by VIRAL GENES found in HUMAN HERPESVIRUS 4. At least six nuclear antigens have been identified.Immunoenzyme Techniques: Immunologic techniques based on the use of: (1) enzyme-antibody conjugates; (2) enzyme-antigen conjugates; (3) antienzyme antibody followed by its homologous enzyme; or (4) enzyme-antienzyme complexes. These are used histologically for visualizing or labeling tissue specimens.Antigens, CD19: Differentiation antigens expressed on B-lymphocytes and B-cell precursors. They are involved in regulation of B-cell proliferation.Antigens, Heterophile: Antigens stimulating the formation of, or combining with heterophile antibodies. They are cross-reacting antigens found in phylogenetically unrelated species.Hepatitis B Core Antigens: The hepatitis B antigen within the core of the Dane particle, the infectious hepatitis virion.Mice, Inbred C57BLSpleen: An encapsulated lymphatic organ through which venous blood filters.Antigens, CD40: A member of the tumor necrosis factor receptor superfamily with specificity for CD40 LIGAND. It is found on mature B-LYMPHOCYTES and some EPITHELIAL CELLS, lymphoid DENDRITIC CELLS. Evidence suggests that CD40-dependent activation of B-cells is important for generation of memory B-cells within the germinal centers. Mutations of the gene for CD40 antigen result in HYPER-IGM IMMUNODEFICIENCY SYNDROME, TYPE 3. Signaling of the receptor occurs through its association with TNF RECEPTOR-ASSOCIATED FACTORS.Immunodiffusion: Technique involving the diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, with the result being a precipitin reaction.Autoantigens: Endogenous tissue constituents that have the ability to interact with AUTOANTIBODIES and cause an immune response.Antibodies: Immunoglobulin molecules having a specific amino acid sequence by virtue of which they interact only with the ANTIGEN (or a very similar shape) that induced their synthesis in cells of the lymphoid series (especially PLASMA CELLS).Immunoglobulin M: A class of immunoglobulin bearing mu chains (IMMUNOGLOBULIN MU-CHAINS). IgM can fix COMPLEMENT. The name comes from its high molecular weight and originally being called a macroglobulin.Antigens, Thy-1: A group of differentiation surface antigens, among the first to be discovered on thymocytes and T-lymphocytes. Originally identified in the mouse, they are also found in other species including humans, and are expressed on brain neurons and other cells.Forssman Antigen: A glycolipid, cross-species antigen that induces production of antisheep hemolysin. It is present on the tissue cells of many species but absent in humans. It is found in many infectious agents.Antigen-Antibody Complex: The complex formed by the binding of antigen and antibody molecules. The deposition of large antigen-antibody complexes leading to tissue damage causes IMMUNE COMPLEX DISEASES.H-Y Antigen: A sex-specific cell surface antigen produced by the sex-determining gene of the Y chromosome in mammals. It causes syngeneic grafts from males to females to be rejected and interacts with somatic elements of the embryologic undifferentiated gonad to produce testicular organogenesis.Molecular Weight: The sum of the weight of all the atoms in a molecule.Antigen-Presenting Cells: A heterogeneous group of immunocompetent cells that mediate the cellular immune response by processing and presenting antigens to the T-cells. Traditional antigen-presenting cells include MACROPHAGES; DENDRITIC CELLS; LANGERHANS CELLS; and B-LYMPHOCYTES. FOLLICULAR DENDRITIC CELLS are not traditional antigen-presenting cells, but because they hold antigen on their cell surface in the form of IMMUNE COMPLEXES for B-cell recognition they are considered so by some authors.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Dendritic Cells: Specialized cells of the hematopoietic system that have branch-like extensions. They are found throughout the lymphatic system, and in non-lymphoid tissues such as SKIN and the epithelia of the intestinal, respiratory, and reproductive tracts. They trap and process ANTIGENS, and present them to T-CELLS, thereby stimulating CELL-MEDIATED IMMUNITY. They are different from the non-hematopoietic FOLLICULAR DENDRITIC CELLS, which have a similar morphology and immune system function, but with respect to humoral immunity (ANTIBODY PRODUCTION).Complement Fixation Tests: Serologic tests based on inactivation of complement by the antigen-antibody complex (stage 1). Binding of free complement can be visualized by addition of a second antigen-antibody system such as red cells and appropriate red cell antibody (hemolysin) requiring complement for its completion (stage 2). Failure of the red cells to lyse indicates that a specific antigen-antibody reaction has taken place in stage 1. If red cells lyse, free complement is present indicating no antigen-antibody reaction occurred in stage 1.HLA-DQ Antigens: A group of the D-related HLA antigens found to differ from the DR antigens in genetic locus and therefore inheritance. These antigens are polymorphic glycoproteins comprising alpha and beta chains and are found on lymphoid and other cells, often associated with certain diseases.Flow Cytometry: Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.Ovalbumin: An albumin obtained from the white of eggs. It is a member of the serpin superfamily.Antigens, CD86: A costimulatory ligand expressed by ANTIGEN-PRESENTING CELLS that binds to CD28 ANTIGEN with high specificity and to CTLA-4 ANTIGEN with low specificity. The interaction of CD86 with CD28 ANTIGEN provides a stimulatory signal to T-LYMPHOCYTES, while its interaction with CTLA-4 ANTIGEN may play a role in inducing PERIPHERAL TOLERANCE.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Simian virus 40: A species of POLYOMAVIRUS originally isolated from Rhesus monkey kidney tissue. It produces malignancy in human and newborn hamster kidney cell cultures.T-Lymphocytes, Cytotoxic: Immunized T-lymphocytes which can directly destroy appropriate target cells. These cytotoxic lymphocytes may be generated in vitro in mixed lymphocyte cultures (MLC), in vivo during a graft-versus-host (GVH) reaction, or after immunization with an allograft, tumor cell or virally transformed or chemically modified target cell. The lytic phenomenon is sometimes referred to as cell-mediated lympholysis (CML). These CD8-positive cells are distinct from NATURAL KILLER CELLS and NATURAL KILLER T-CELLS. There are two effector phenotypes: TC1 and TC2.Receptors, Antigen, T-Cell, alpha-beta: T-cell receptors composed of CD3-associated alpha and beta polypeptide chains and expressed primarily in CD4+ or CD8+ T-cells. Unlike immunoglobulins, the alpha-beta T-cell receptors recognize antigens only when presented in association with major histocompatibility (MHC) molecules.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Antibodies, Viral: Immunoglobulins produced in response to VIRAL ANTIGENS.Immunoelectrophoresis: A technique that combines protein electrophoresis and double immunodiffusion. In this procedure proteins are first separated by gel electrophoresis (usually agarose), then made visible by immunodiffusion of specific antibodies. A distinct elliptical precipitin arc results for each protein detectable by the antisera.Immunity, Cellular: Manifestations of the immune response which are mediated by antigen-sensitized T-lymphocytes via lymphokines or direct cytotoxicity. This takes place in the absence of circulating antibody or where antibody plays a subordinate role.CTLA-4 Antigen: An inhibitory T CELL receptor that is closely related to CD28 ANTIGEN. It has specificity for CD80 ANTIGEN and CD86 ANTIGEN and acts as a negative regulator of peripheral T cell function. CTLA-4 antigen is believed to play role in inducing PERIPHERAL TOLERANCE.Lymphocytes: White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.Interferon-gamma: The major interferon produced by mitogenically or antigenically stimulated LYMPHOCYTES. It is structurally different from TYPE I INTERFERON and its major activity is immunoregulation. It has been implicated in the expression of CLASS II HISTOCOMPATIBILITY ANTIGENS in cells that do not normally produce them, leading to AUTOIMMUNE DISEASES.Antigens, CD79: A component of the B-cell antigen receptor that is involved in B-cell antigen receptor heavy chain transport to the PLASMA MEMBRANE. It is expressed almost exclusively in B-LYMPHOCYTES and serves as a useful marker for B-cell NEOPLASMS.Antibodies, Protozoan: Immunoglobulins produced in a response to PROTOZOAN ANTIGENS.CA-19-9 Antigen: Sialylated Lewis blood group carbohydrate antigen found in many adenocarcinomas of the digestive tract, especially pancreatic tumors.Recombinant Proteins: Proteins prepared by recombinant DNA technology.CD4-Positive T-Lymphocytes: A critical subpopulation of T-lymphocytes involved in the induction of most immunological functions. The HIV virus has selective tropism for the T4 cell which expresses the CD4 phenotypic marker, a receptor for HIV. In fact, the key element in the profound immunosuppression seen in HIV infection is the depletion of this subset of T-lymphocytes.Hemagglutination Tests: Sensitive tests to measure certain antigens, antibodies, or viruses, using their ability to agglutinate certain erythrocytes. (From Stedman, 26th ed)gp100 Melanoma Antigen: A melanosome-associated protein that plays a role in the maturation of the MELANOSOME.Serologic Tests: Diagnostic procedures involving immunoglobulin reactions.CD8-Positive T-Lymphocytes: A critical subpopulation of regulatory T-lymphocytes involved in MHC Class I-restricted interactions. They include both cytotoxic T-lymphocytes (T-LYMPHOCYTES, CYTOTOXIC) and CD8+ suppressor T-lymphocytes.Lewis Blood-Group System: A group of dominantly and independently inherited antigens associated with the ABO blood factors. They are glycolipids present in plasma and secretions that may adhere to the erythrocytes. The phenotype Le(b) is the result of the interaction of the Le gene Le(a) with the genes for the ABO blood groups.Mice, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.Ki-67 Antigen: A CELL CYCLE and tumor growth marker which can be readily detected using IMMUNOCYTOCHEMISTRY methods. Ki-67 is a nuclear antigen present only in the nuclei of cycling cells.Antibodies, Helminth: Immunoglobulins produced in a response to HELMINTH ANTIGENS.Antigens, T-Independent: Antigens which may directly stimulate B lymphocytes without the cooperation of T lymphocytes.Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Antigens, CD2: Glycoprotein members of the immunoglobulin superfamily which participate in T-cell adhesion and activation. They are expressed on most peripheral T-lymphocytes, natural killer cells, and thymocytes, and function as co-receptors or accessory molecules in the T-cell receptor complex.Immune Tolerance: The specific failure of a normally responsive individual to make an immune response to a known antigen. It results from previous contact with the antigen by an immunologically immature individual (fetus or neonate) or by an adult exposed to extreme high-dose or low-dose antigen, or by exposure to radiation, antimetabolites, antilymphocytic serum, etc.Hepatitis B e Antigens: A closely related group of antigens found in the plasma only during the infective phase of hepatitis B or in virulent chronic hepatitis B, probably indicating active virus replication; there are three subtypes which may exist in a complex with immunoglobulins G.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Hypersensitivity, Delayed: An increased reactivity to specific antigens mediated not by antibodies but by cells.Cytotoxicity, Immunologic: The phenomenon of target cell destruction by immunologically active effector cells. It may be brought about directly by sensitized T-lymphocytes or by lymphoid or myeloid "killer" cells, or it may be mediated by cytotoxic antibody, cytotoxic factor released by lymphoid cells, or complement.Antigens, CD28: Costimulatory T-LYMPHOCYTE receptors that have specificity for CD80 ANTIGEN and CD86 ANTIGEN. Activation of this receptor results in increased T-cell proliferation, cytokine production and promotion of T-cell survival.Antigens, CD95: A tumor necrosis factor receptor subtype found in a variety of tissues and on activated LYMPHOCYTES. It has specificity for FAS LIGAND and plays a role in regulation of peripheral immune responses and APOPTOSIS. Multiple isoforms of the protein exist due to multiple ALTERNATIVE SPLICING. The activated receptor signals via a conserved death domain that associates with specific TNF RECEPTOR-ASSOCIATED FACTORS in the CYTOPLASM.CA-125 Antigen: Carbohydrate antigen most commonly seen in tumors of the ovary and occasionally seen in breast, kidney, and gastrointestinal tract tumors and normal tissue. CA 125 is clearly tumor-associated but not tumor-specific.Autoantibodies: Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.Antigens, Nuclear: Immunologically detectable substances found in the CELL NUCLEUS.Minor Histocompatibility Antigens: Allelic alloantigens often responsible for weak graft rejection in cases when (major) histocompatibility has been established by standard tests. In the mouse they are coded by more than 500 genes at up to 30 minor histocompatibility loci. The most well-known minor histocompatibility antigen in mammals is the H-Y antigen.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Hybridomas: Cells artificially created by fusion of activated lymphocytes with neoplastic cells. The resulting hybrid cells are cloned and produce pure MONOCLONAL ANTIBODIES or T-cell products, identical to those produced by the immunologically competent parent cell.HLA-B27 Antigen: A specific HLA-B surface antigen subtype. Members of this subtype contain alpha chains that are encoded by the HLA-B*27 allele family.Major Histocompatibility Complex: The genetic region which contains the loci of genes which determine the structure of the serologically defined (SD) and lymphocyte-defined (LD) TRANSPLANTATION ANTIGENS, genes which control the structure of the IMMUNE RESPONSE-ASSOCIATED ANTIGENS, HUMAN; the IMMUNE RESPONSE GENES which control the ability of an animal to respond immunologically to antigenic stimuli, and genes which determine the structure and/or level of the first four components of complement.Immunoassay: A technique using antibodies for identifying or quantifying a substance. Usually the substance being studied serves as antigen both in antibody production and in measurement of antibody by the test substance.Clone Cells: A group of genetically identical cells all descended from a single common ancestral cell by mitosis in eukaryotes or by binary fission in prokaryotes. Clone cells also include populations of recombinant DNA molecules all carrying the same inserted sequence. (From King & Stansfield, Dictionary of Genetics, 4th ed)Hepatitis delta Antigens: Antigens produced by various strains of HEPATITIS D VIRUS.HLA-C Antigens: Class I human histocompatibility (HLA) antigens encoded by a small cluster of structural genes at the C locus on chromosome 6. They have significantly lower immunogenicity than the HLA-A and -B determinants and are therefore of minor importance in donor/recipient crossmatching. Their primary role is their high-risk association with certain disease manifestations (e.g., spondylarthritis, psoriasis, multiple myeloma).Antigens, CD58: Glycoproteins with a wide distribution on hematopoietic and non-hematopoietic cells and strongly expressed on macrophages. CD58 mediates cell adhesion by binding to CD2; (ANTIGENS, CD2); and this enhances antigen-specific T-cell activation.Antigens, CD1d: A major histocompatibily complex class I-like protein that plays a unique role in the presentation of lipid ANTIGENS to NATURAL KILLER T-CELLS.HLA-A1 Antigen: A specific HLA-A surface antigen subtype. Members of this subtype contain alpha chains that are encoded by the HLA-A*01 allele family.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.HLA-B7 Antigen: A specific HLA-B surface antigen subtype. Members of this subtype contain alpha chains that are encoded by the HLA-B*07 allele family.Polysaccharides, Bacterial: Polysaccharides found in bacteria and in capsules thereof.HLA-DR4 Antigen: An HLA-DR antigen which is associated with HLA-DRB1 CHAINS encoded by DRB1*04 alleles.HLA-DR3 Antigen: An HLA-DR antigen which is associated with HLA-DRB1 CHAINS encoded by DRB1*03 alleles.ABO Blood-Group System: The major human blood type system which depends on the presence or absence of two antigens A and B. Type O occurs when neither A nor B is present and AB when both are present. A and B are genetic factors that determine the presence of enzymes for the synthesis of certain glycoproteins mainly in the red cell membrane.Agglutination Tests: Tests that are dependent on the clumping of cells, microorganisms, or particles when mixed with specific antiserum. (From Stedman, 26th ed)Vaccines, Synthetic: Small synthetic peptides that mimic surface antigens of pathogens and are immunogenic, or vaccines manufactured with the aid of recombinant DNA techniques. The latter vaccines may also be whole viruses whose nucleic acids have been modified.Membrane Glycoproteins: Glycoproteins found on the membrane or surface of cells.Antigens, CD5: Glycoproteins expressed on all mature T-cells, thymocytes, and a subset of mature B-cells. Antibodies specific for CD5 can enhance T-cell receptor-mediated T-cell activation. The B-cell-specific molecule CD72 is a natural ligand for CD5. (From Abbas et al., Cellular and Molecular Immunology, 2d ed, p156)Prostatic Neoplasms: Tumors or cancer of the PROSTATE.Antigens, CD20: Unglycosylated phosphoproteins expressed only on B-cells. They are regulators of transmembrane Ca2+ conductance and thought to play a role in B-cell activation and proliferation.Antigens, CD27: A member of the tumor necrosis factor receptor superfamily found on most T-LYMPHOCYTES. Activation of the receptor by CD70 ANTIGEN results in the increased proliferation of CD4-POSITIVE T-LYMPHOCYTES and CD8-POSITIVE T-LYMPHOCYTES. Signaling by the activated receptor occurs through its association with TNF RECEPTOR-ASSOCIATED FACTORS.HLA-A24 Antigen: A specific HLA-A surface antigen subtype. Members of this subtype contain alpha chains that are encoded by the HLA-A*24 allele family.Antigens, CD34: Glycoproteins found on immature hematopoietic cells and endothelial cells. They are the only molecules to date whose expression within the blood system is restricted to a small number of progenitor cells in the bone marrow.Isoantigens: Antigens that exist in alternative (allelic) forms in a single species. When an isoantigen is encountered by species members who lack it, an immune response is induced. Typical isoantigens are the BLOOD GROUP ANTIGENS.Binding Sites, Antibody: Local surface sites on antibodies which react with antigen determinant sites on antigens (EPITOPES.) They are formed from parts of the variable regions of FAB FRAGMENTS.Cancer Vaccines: Vaccines or candidate vaccines designed to prevent or treat cancer. Vaccines are produced using the patient's own whole tumor cells as the source of antigens, or using tumor-specific antigens, often recombinantly produced.Blotting, Western: Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.Vaccination: Administration of vaccines to stimulate the host's immune response. This includes any preparation intended for active immunological prophylaxis.Tumor Cells, Cultured: Cells grown in vitro from neoplastic tissue. If they can be established as a TUMOR CELL LINE, they can be propagated in cell culture indefinitely.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Adjuvants, Immunologic: Substances that augment, stimulate, activate, potentiate, or modulate the immune response at either the cellular or humoral level. The classical agents (Freund's adjuvant, BCG, Corynebacterium parvum, et al.) contain bacterial antigens. Some are endogenous (e.g., histamine, interferon, transfer factor, tuftsin, interleukin-1). Their mode of action is either non-specific, resulting in increased immune responsiveness to a wide variety of antigens, or antigen-specific, i.e., affecting a restricted type of immune response to a narrow group of antigens. The therapeutic efficacy of many biological response modifiers is related to their antigen-specific immunoadjuvanticity.Dose-Response Relationship, Immunologic: A specific immune response elicited by a specific dose of an immunologically active substance or cell in an organism, tissue, or cell.Glycoproteins: Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.Mice, Transgenic: Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.Bacterial Proteins: Proteins found in any species of bacterium.Lymph Nodes: They are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system.Immunoblotting: Immunologic method used for detecting or quantifying immunoreactive substances. The substance is identified by first immobilizing it by blotting onto a membrane and then tagging it with labeled antibodies.Radioimmunoassay: Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.Immunoglobulin A: Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory IgA (IMMUNOGLOBULIN A, SECRETORY) is the main immunoglobulin in secretions.Recombinant Fusion Proteins: Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.Receptors, Antigen, T-Cell, gamma-delta: T-cell receptors composed of CD3-associated gamma and delta polypeptide chains and expressed primarily in CD4-/CD8- T-cells. The receptors appear to be preferentially located in epithelial sites and probably play a role in the recognition of bacterial antigens. The T-cell receptor gamma/delta chains are separate and not related to the gamma and delta chains which are subunits of CD3 (see ANTIGENS, CD3).Antigens, CD7: Differentiation antigens expressed on pluripotential hematopoietic cells, most human thymocytes, and a major subset of peripheral blood T-lymphocytes. They have been implicated in integrin-mediated cellular adhesion and as signalling receptors on T-cells.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Bacterial Vaccines: Suspensions of attenuated or killed bacteria administered for the prevention or treatment of infectious bacterial disease.Immunoelectrophoresis, Two-Dimensional: Immunoelectrophoresis in which a second electrophoretic transport is performed on the initially separated antigen fragments into an antibody-containing medium in a direction perpendicular to the first electrophoresis.HLA-DR7 Antigen: A HLA-DR antigen that is associated with HLA-DRB1 CHAINS encoded by DRB1*07 alleles.Hepatitis Antigens: Antigens from any of the hepatitis viruses including surface, core, and other associated antigens.Immunoglobulins: Multi-subunit proteins which function in IMMUNITY. They are produced by B LYMPHOCYTES from the IMMUNOGLOBULIN GENES. They are comprised of two heavy (IMMUNOGLOBULIN HEAVY CHAINS) and two light chains (IMMUNOGLOBULIN LIGHT CHAINS) with additional ancillary polypeptide chains depending on their isoforms. The variety of isoforms include monomeric or polymeric forms, and transmembrane forms (B-CELL ANTIGEN RECEPTORS) or secreted forms (ANTIBODIES). They are divided by the amino acid sequence of their heavy chains into five classes (IMMUNOGLOBULIN A; IMMUNOGLOBULIN D; IMMUNOGLOBULIN E; IMMUNOGLOBULIN G; IMMUNOGLOBULIN M) and various subclasses.Isoantibodies: Antibodies from an individual that react with ISOANTIGENS of another individual of the same species.Mice, Inbred CBAHLA-A3 Antigen: A specific HLA-A surface antigen subtype. Members of this subtype contain alpha chains that are encoded by the HLA-A*03 allele family.Immunologic Memory: The altered state of immunologic responsiveness resulting from initial contact with antigen, which enables the individual to produce antibodies more rapidly and in greater quantity in response to secondary antigenic stimulus.Antigens, CD11c: An integrin alpha subunit of approximately 150-kDa molecular weight. It is expressed at high levels on monocytes and combines with CD18 ANTIGEN to form the cell surface receptor INTEGRIN ALPHAXBETA2. The subunit contains a conserved I-domain which is characteristic of several of alpha integrins.Herpesvirus 4, Human: The type species of LYMPHOCRYPTOVIRUS, subfamily GAMMAHERPESVIRINAE, infecting B-cells in humans. It is thought to be the causative agent of INFECTIOUS MONONUCLEOSIS and is strongly associated with oral hairy leukoplakia (LEUKOPLAKIA, HAIRY;), BURKITT LYMPHOMA; and other malignancies.Antibody Affinity: A measure of the binding strength between antibody and a simple hapten or antigen determinant. It depends on the closeness of stereochemical fit between antibody combining sites and antigen determinants, on the size of the area of contact between them, and on the distribution of charged and hydrophobic groups. It includes the concept of "avidity," which refers to the strength of the antigen-antibody bond after formation of reversible complexes.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Melanoma: A malignant neoplasm derived from cells that are capable of forming melanin, which may occur in the skin of any part of the body, in the eye, or, rarely, in the mucous membranes of the genitalia, anus, oral cavity, or other sites. It occurs mostly in adults and may originate de novo or from a pigmented nevus or malignant lentigo. Melanomas frequently metastasize widely, and the regional lymph nodes, liver, lungs, and brain are likely to be involved. The incidence of malignant skin melanomas is rising rapidly in all parts of the world. (Stedman, 25th ed; from Rook et al., Textbook of Dermatology, 4th ed, p2445)Cytotoxicity Tests, Immunologic: The demonstration of the cytotoxic effect on a target cell of a lymphocyte, a mediator released by a sensitized lymphocyte, an antibody, or complement.Genes, MHC Class II: Genetic loci in the vertebrate major histocompatibility complex that encode polymorphic products which control the immune response to specific antigens. The genes are found in the HLA-D region in humans and in the I region in mice.HemocyaninCell Division: The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.Antibodies, Anti-Idiotypic: Antibodies which react with the individual structural determinants (idiotopes) on the variable region of other antibodies.Cross-Priming: Class I-restricted activation of CD8-POSITIVE LYMPHOCYTES resulting from ANTIGEN PRESENTATION of exogenous ANTIGENS (cross-presentation). This is in contrast to normal activation of these lymphocytes (direct-priming) which results from presentation of endogenous antigens.HLA-B44 Antigen: A specific HLA-B surface antigen subtype. Members of this subtype contain alpha chains that are encoded by the HLA-B*44 allele family.Epitopes, T-Lymphocyte: Antigenic determinants recognized and bound by the T-cell receptor. Epitopes recognized by the T-cell receptor are often located in the inner, unexposed side of the antigen, and become accessible to the T-cell receptors after proteolytic processing of the antigen.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Counterimmunoelectrophoresis: Immunoelectrophoresis in which immunoprecipitation occurs when antigen at the cathode is caused to migrate in an electric field through a suitable medium of diffusion against a stream of antibody migrating from the anode as a result of endosmotic flow.Thymus Gland: A single, unpaired primary lymphoid organ situated in the MEDIASTINUM, extending superiorly into the neck to the lower edge of the THYROID GLAND and inferiorly to the fourth costal cartilage. It is necessary for normal development of immunologic function early in life. By puberty, it begins to involute and much of the tissue is replaced by fat.Peptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Immunologic Techniques: Techniques used to demonstrate or measure an immune response, and to identify or measure antigens using antibodies.Haptens: Small antigenic determinants capable of eliciting an immune response only when coupled to a carrier. Haptens bind to antibodies but by themselves cannot elicit an antibody response.Macrophages: The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood MONOCYTES. Main types are PERITONEAL MACROPHAGES; ALVEOLAR MACROPHAGES; HISTIOCYTES; KUPFFER CELLS of the liver; and OSTEOCLASTS. They may further differentiate within chronic inflammatory lesions to EPITHELIOID CELLS or may fuse to form FOREIGN BODY GIANT CELLS or LANGHANS GIANT CELLS. (from The Dictionary of Cell Biology, Lackie and Dow, 3rd ed.)

Heterogeneity in the ability of cytotoxic murine NK cell clones to enhance Ig secretion in vitro. (1/168)

We recently described a panel of cytotoxic murine NK cell clones that also enhanced Ig secretion by B cells activated in an in vitro model of T cell-independent type 2 (TI-2) responses. We employed dextran-conjugated anti-IgD (alphadelta-dex) as a model antigen. Here we study the mechanism of Ig induction by these clones. Addition of the various NK clones to sort-purified B cells stimulated with alphadelta-dex and IL-2 resulted in a markedly heterogeneous increase in Ig secretion, which varied from 3-fold, as mediated by clone PKO 56, to 15-fold, as induced by clone PKO 101. The other NK cells showed intermediate levels of Ig induction. Furthermore, while addition of as few as 0.04% of PKO 101 cells stimulated significant increases and 1% induced near maximum Ig production, a 3% addition of PKO 56 cells was required for significant enhancement of Ig secretion. Supernatant material collected from the NK clones mediated Ig production at levels that mirrored the induction by the corresponding cells. Cytokine analysis showed that while all members of the NK panel produced IFN-gamma only two secreted granulocyte macrophage colony stimulating factor and that the levels of Ig induction mediated by the NK clones correlated only with their levels of IFN-gamma secretion. Culture of B and NK cells in the presence of anti-IFN-gamma demonstrated that IFN-gamma was the critical cytokine in NK-induced Ig production. These findings establish heterogeneity in the ability of NK cells to increase Ig secretion in vitro and show that NK-produced IFN-gamma is an important factor in determining this heterogeneity.  (+info)

Impaired allostimulatory capacity of peripheral blood dendritic cells recovered from hepatitis C virus-infected individuals. (2/168)

In hepatitis C virus (HCV) infection, Th responses are implicated in the pathogenesis of liver disease. The dendritic cell (DC) is the most potent activator of CD4 T cells for supporting Th1 differentiation. To clarify the roles of DC of HCV-infected individuals in the development of CD4 T cell responses, we generated peripheral DC with GM-CSF and IL-4 from 24 chronic hepatitis C patients and 14 healthy donors. We then compared their potentials for stimulating allogeneic CD4 T cells, autologous CD4 T cells against influenza A or HCV core Ags, and cytokine production. The DC from the patients (HCV-DC) expressed lower degrees of CD86 than DC from the donors (N-DC), whereas no difference was found in the HLA molecules and other costimulators. HCV-DC stimulated allogeneic T cells less than N-DC; however, influenza A- or core-pulsed HCV-DC retained the potentials for autologous T cell proliferation. In allogeneic DC/T cell cultures, the IFN-gamma levels with HCV-DC were lower than those with N-DC, which may be related to the low expressions of IL-12 p35 and p40 transcripts in HCV-DC. The stimulation with LPS disclosed that HCV-DC is less potent in IL-12 p70 production than N-DC. In the autologous cultures, the pulsing of the Ags to HCV-DC increased the IL-12 p40 and IFN-gamma production and up-regulated the transcription of both IL-12 subunits. Exogenous IL-2 or IL-12 restored the low allogeneic T cell proliferation with HCV-DC in a dose-dependent manner. Therefore, low expression of CD86 and/or IL-12 is crucially involved in the low allostimulatory capacity of HCV-DC. Low IL-12 and low IFN-gamma milieu with HCV-DC on encounters with alloantigens may impede Th1 polarization.  (+info)

Elderly immune response to a TI-2 antigen: heavy and light chain use and bactericidal activity to Neisseria meningitidis serogroup C polysaccharide. (3/168)

Previous studies of the elderly immune response to TI-2 antigens failed to correlate specific antibody levels with function and to compare responses with those of young adults. Neisseria meningitidis serogroup C capsular polysaccharide (MCPS) was used as a model TI-2 antigen. Anti-MCPS antibody levels were determined in elderly individuals and correlated with bactericidal activity. The anti-MCPS response in most persons was characterized by predominant IgG usage, with IgG2>IgG1. No light chain or IgA subclass predominated, but some responses showed a particular chain type. Bactericidal activity correlated best with IgG2 levels. Elderly subjects had lower anti-MCPS responses than the young adults did in all chain-specific anti-MCPS levels, and levels declined more rapidly. Bactericidal activity following immunization was significantly lower in the elderly persons. These results suggest the anti-MCPS antibody repertoire in the elderly is likely maintained, and the lower level of function is related to the lower antibody levels.  (+info)

Genetic dissection of Sle pathogenesis: Sle3 on murine chromosome 7 impacts T cell activation, differentiation, and cell death. (4/168)

Polyclonal, generalized T cell defects, as well as Ag-specific Th clones, are likely to contribute to pathology in murine lupus, but the genetic bases for these mechanisms remain unknown. Mapping studies indicate that loci on chromosomes 1 (Sle1), 4 (Sle2), 7 (Sle3), and 17 (Sle4) confer disease susceptibility in the NZM2410 lupus strain. B6.NZMc7 mice are C57BL/6 (B6) mice congenic for the NZM2410-derived chromosome 7 susceptibility interval, bearing Sle3. Compared with B6 controls, B6.NZMc7 mice exhibit elevated CD4:CD8 ratios (2.0 vs 1.34 in 1- to 3-mo-old spleens); an age-dependent accumulation of activated CD4+ T cells (33.4% vs 21.9% in 9- to 12-mo-old spleens); a more diffuse splenic architecture; and a stronger immune response to T-dependent, but not T-independent, Ags. In vitro, Sle3-bearing T cells show stronger proliferation, increased expansion of CD4+ T cells, and reduced apoptosis (with or without anti-Fas) following stimulation with anti-CD3. With age, the B cells in this strain acquire an activated phenotype. Thus, the NZM2410 allele of Sle3 appears to impact generalized T cell activation, and this may be causally related to the low grade, polyclonal serum autoantibodies seen in this strain. Epistatic interactions with other loci may be required to transform this relatively benign phenotype into overt autoimmunity, as seen in the NZM2410 strain.  (+info)

Deficiency in Msh2 affects the efficiency and local sequence specificity of immunoglobulin class-switch recombination: parallels with somatic hypermutation. (5/168)

During maturation of the immune response, IgM+ B cells switch to expression of one of the downstream isotypes (IgG, A or E). This class switching occurs by region-specific recombination within the IgH locus through an unknown mechanism. A lack of switch recombination in mice deficient in components of the DNA-dependent protein kinase (DNA-PK)-Ku complex has pointed to a role for non-homologous end joining. Here we characterize a switching defect in mice lacking a protein involved in DNA mismatch recognition. Mice deficient in Msh2 give diminished IgG (but not IgM) responses following challenge with both T cell-dependent and T cell-independent antigens. This appears to reflect a B cell-intrinsic defect since B cells from Msh2-deficient mice also exhibit impaired switching (but not blasting or proliferation) on in vitro culture with lipopolysaccharide. Furthermore, those switches that do occur in Msh2-deficient B cells reveal a shift in the distribution of recombination sites used: the breakpoints are more likely to occur in consensus motifs. These results, which intriguingly parallel the effects of Msh2 deficiency on hypermutation, suggest a role for Msh2 in the mechanics of class-switch recombination.  (+info)

Cutting edge: CD40 ligand is a limiting factor in the humoral response to T cell-dependent antigens. (6/168)

CD40 ligand (CD40L) plays a crucial role in T cell-dependent B cell responses, but whether its abundance is a limiting factor in their development is unclear. This question was addressed in transgenic mice expressing the murine CD40L gene under the control of the IL-2-promoter (CD40Ltg+). The fraction of activated T cells from the CD40Ltg+ mice with detectable levels of surface CD40L was modestly greater (1.1- to 2-fold) than littermate controls and paralleled an approximately 1.8-fold increase in CD40L mRNA abundance. In response to trinitrophenol (TNP)-keyhole limpet hemocyanin and tetanus/diphtheria vaccine, CD40Ltg+ mice developed higher titers of high-affinity IgG and IgG1 Ab than wild-type mice. In contrast, the Ab response of CD40Ltg+ and control mice was similar in response to the T-independent Ag TNP-Ficoll. These results suggest that a modest increment in expression of CD40L accelerates the development of T-dependent responses, and that CD40L plays a limiting role in the induction of high-affinity Ab and Ab-class switching.  (+info)

Comparative contribution of CD1 on the development of CD4+ and CD8+ T cell compartments. (7/168)

CD1 molecules are MHC class I-like glycoproteins whose expression is essential for the development of a unique subset of T cells, the NK T cells. To evaluate to what extent CD1 contributes to the development of CD4+ and CD8+ T cells, we generated CD1oIIo and CD1oTAPo mice and compared the generation of T cells in these double-mutant mice and IIo or TAPo mice. FACS analysis showed that the number of CD4+ T cells in CD1oIIo mice was reduced significantly compared with the corresponding population in IIo mice. Both CD4+ NK1.1+ and the CD4+ NK1.1- population were reduced in CD1oIIo mice, suggesting that CD1 can select not only CD4+ NK1.1+ T cells but also some NK1.1- CD4+ T cells. Functional analysis showed that the residual CD4+ cells in CD1oIIo can secrete large amounts of IFN-gamma and a significant amount of IL-4 during primary stimulation with anti-CD3, suggesting that this population may be enriched for NK T cells restricted by other class I molecules. In contrast to the CD4+ population, no significant differences in the CD8+ T cell compartment can be detected between TAPo and CD1oTAPo mice in all lymphoid tissues tested, including intestinal intraepithelial lymphocytes. Our data suggest that, unlike other MHC class I molecules, CD1 does not contribute in a major way to the development of CD8+ T cells.  (+info)

Ox40-ligand has a critical costimulatory role in dendritic cell:T cell interactions. (8/168)

The tumor necrosis factor family molecule Ox40-ligand (Ox40L) has been identified as a potential costimulatory molecule and also has been implicated in T cell homing and B cell activation. To ascertain the essential functions of Ox40L, we generated and characterized Ox40L-deficient mice. Mice lacking Ox40L exhibit an impaired contact hypersensitivity response, a dendritic cell-dependent T cell-mediated response, due to defects in T cell priming and cytokine production. In contrast, Ox40L-deficient mice do not have defects in T cell homing or humoral immune responses. In vitro, Ox40L-deficient dendritic cells are defective in costimulating T cell cytokine production. Thus, Ox40L has a critical costimulatory function in vitro and in vivo for dendritic cell:T cell interactions.  (+info)

  • However, in competition experiments only the high-affinity B cells responded to antigen. (
  • Thus, in TI-2 immune responses, large differences in affinity produce only small differences in the intrinsic ability of B cells to respond to antigen, and selection for high-affinity clones is due to clonal competition during the earliest stages of the response. (
  • TI-1 antigen, which has an activity that can directly activate B cells and TI-2 antigen, which has highly repetitive structure and causes simultaneous cross-linking of specific B cell receptors (BCR) on B lymphocyte. (
  • T independent antigens are divided into 2 classes by the mechanism of activating B cells. (
  • On the other hand, the anti-delta antibody had no effect on the anti-TNP response of BC8 spleen cells to TNP-BA, except at limiting antigen concentrations. (
  • Both TNP-AECM-Ficoll and TNP-BA are T-I antigens, but they differ in that TNP-AECM-Ficoll fails to stimulate in vitro responses by immunologically defective CBA/N and neonatal spleen cells whereas TNP-BA can cause responses from both these animals. (
  • Increases in cytoplasmic free calcium ([Ca2+]i) can be induced in resting B cells either by a low molecular weight (12-kDa) B-cell growth factor (LMW-BCGF) or by crosslinking the B-cell antigen CD19 with monoclonal antibody (mAb). (
  • Two predominant pathways are defined that require the concerted action of multivalent membrane Ig cross-linking by the polysaccharide Ag with 1) various B cell-activating moieties contained within the bacterial pathogen and/or 2) cytokines, such as IFN-gamma and granulocyte-macrophage colony-stimulating factor produced by NK cells and macrophages, that become activated in a T cell-independent manner during bacterial infection. (
  • Recent studies suggested the existence of a subset of B cells that undergoes SHM in an antigen-independent fashion outside GCs ( 3 ), but this viewpoint has remained controversial. (
  • In this study, we review recent work showing that T cell-independent Ags consisting of either polysaccharides or LPSs also induce the formation of long-lived plasma cells, despite their general inability to sustain germinal center responses. (
  • However, as addressed below, recent evidence suggests that B cell responses that fail to engender bona fide GC responses, such as responses to T cell-independent Ags, also generate long-lived plasma cells. (
  • Along the way, we consider historical precedents driving the notion that plasma cells possess markedly distinct lifespans, as well as the idea that T cell-independent Ags are relatively ineffective at inducing the formation of long-lived plasma cells. (
  • Differences between SA-dependent and SA-independent strains extend beyond the ability or inability of their spike proteins to bind SA: SA-independent strains are generally more fastidious in cell culture than SA-dependent strains ( 40 , 42 ), and although SA-independent strains infect polarized epithelial cells from either the apical or basolateral membrane, SA-dependent strains enter only at the apical surface ( 4 ). (
  • Moreover, LPS or HIV-1-activated dendritic cells (DCs) stimulated CD8(+) T cells in an IL-15-dependent but Ag-independent manner, and IL-15 expression was highly increased in DCs isolated from viremic HIV-1 patients, suggesting that CD8(+) T cells are activated by inflammatory cytokines in untreated HIV-1 patients independent of Ag specificity. (
  • These observations demonstrate that mature T cells are required for cyclical idiotypic and anti-idiotypic responses to immunization with a T-independent antigen and suggest that the cyclical immune response may result from an interaction between idiotypic and anti-idiotypic cell clones. (
  • A conserved TAP-independent HLA peptide ligand endogenously processed and presented in infected human cells was identified. (
  • It was not the case that AODH 7.1 cells were responding to Con A on a neighboring AODH 7.1 cell, and no class II antigens were involved. (
  • The self-antigens may be found in all cell types (e.g. chromatin, centromeres) and those autoimmune diseases is systemic or be highly specific for a specific cell type in one organ of the body (e.g. thyroglobulin in cells of the thyroid gland) and those autoimmune diseases is organ-specific. (
  • We generated MHC-independent chimeric antigen receptors (CARs) directed to the GD2 antigen expressed by neuroblastoma tumor cells and treated patients with this disease. (
  • Introduction Adoptively transferred T cells Rabbit Polyclonal to ZADH2 can recognize tumor-associated antigens presented in association with MHC molecules on the cell surface. (
  • However, many cancer cells and solid tumors have defects in antigen processing and presentation,1,2 including down-regulation of and/or failure to express MHC molecules.3,4 Introducing tumor-specific chimeric antigen receptors (CARs) into adoptively transferred T cells allows them to recognize tumor-associated antigens in an Resminostat hydrochloride manufacture MHC-independent manner while retaining their cytotoxic activity. (
  • We found that CAR expressing EBV-CTLs (CAR-CTLs) survived in the circulation at an initially higher level over the 6-week study period than GD2-CAR expressing activated T cells (CAR-ATCs), a difference Resminostat hydrochloride manufacture we attributed to superior costimulation for CAR-CTLs provided when the cells engaged EBV antigens on professional antigen-presenting cells through their native receptors. (
  • Therefore, there is more evidence that field cancerization is due to multiple independent events than to migration of genetically altered cells. (
  • Although the size and diversity of the lymphocyte repertoire make it likely that there is an antigen, a specific lymphocyte for any given pathogen, the frequency of these cells can be extremely low and normally will not be sufficient to protect the host against a primary infection. (
  • After antigenic stimulation, there is activation and expansion of these antigen-specific cells. (
  • It is this process of clonal selection and the ultimate perpetuation of these antigen-specific memory cells that protects against a secondary infection. (
  • Hence, the goal of vaccination is to enhance the number of antigen-specific B and T cells against a given pathogen. (
  • Antigens on the body's own cells are called autoantigens. (
  • Antigens on all other cells are called foreign antigens. (
  • Reactions to antigens by T and B cells are part of the specific immune response. (
  • Furthermore, for a peptide to induce an immune response (activation of T-cells by antigen-presenting cells ) it must be a large enough size, since peptides too small will also not elicit an immune response. (
  • The immune system is supposed to identify and attack "non-self" invaders from the outside world or modified/harmful substances present in the body and usually does not react to self-antigens under normal homeostatic conditions due to negative selection of T cells in the thymus . (
  • Superantigen - A class of antigens that cause non-specific activation of T-cells, resulting in polyclonal T-cell activation and massive cytokine release. (
  • Consequently, in coreceptor-deficient mice that additionally lack MHC [so-called QuadKO mice ( 10 )], MHC-independent TCRs signal immature thymocytes to undergo positive selection and to differentiate into mature T cells expressing only an MHC-independent TCR repertoire. (
  • Adoptive transfer of CD4+ T cells from sensitized rats induced an increase in proliferation and inhibition of apoptosis of airway myocytes in naive recipients upon repeated antigen challenge, which resulted in an increase in ASM mass. (
  • Coculture of antigen-stimulated CD4+ T cells with cell cycle-arrested ASM cells induced myocyte proliferation, dependent on T cell activation and direct T cell-myocyte contact. (
  • Antigen presenting cells present antigens in the form of peptides on histocompatibility molecules. (
  • Depending on the antigen and the type of the histocompatibility molecule, different types of T cells will be activated. (
  • citation needed] Non-microbial non-self antigens can include pollen, egg white and proteins from transplanted tissues and organs or on the surface of transfused blood cells. (
  • Most significantly, the newly acquired MHC class II molecules were capable of efficiently presenting antigen to T helper cells. (
  • T helper cells recognize processed antigen (Ag) in the context of major histocompatibility complex (MHC) class II antigens present on the surface of B cells and other Ag-presenting cells. (
  • In this study, the binding of a soluble recombinant CD4/Ig heavy chain fusion protein (CD4-gamma 3) or monoclonal antibody (mAb) to class II antigens on human B cells was shown to induce rapid and specific homotypic adhesion of B cells and most B lymphoblastoid cell lines. (
  • Purpose: The goal of this study is to develop a tissue-specific toxic gene therapy utilizing the prostate specific antigen (PSA) promoter for both androgen-dependent (AD) and androgen-independent (AI) PSA-secreting prostate cancer cells. (
  • Conclusion: The 5837 bp long PSA promoter was active in the androgen free environment and could be used to target both androgen-dependent and independent PSA-producing prostate cancer cells in vitro, and prostate tumors in castrated hosts. (
  • To forward such efforts, our approach with colonization factor antigen I (CFA/I) fimbriae is to establish bystander immunity to ultimately drive the development of auto-Ag-specific Treg cells. (
  • This review article will examine the potential of treating autoimmune diseases without having previous knowledge of the auto-Ag using an innocuous antigen to stimulate Treg cells via the production of transforming growth factor-beta and interleukin-10. (
  • For autoimmune conditions like type 1 diabetes to progress, self-reactive CD8 + T cells would need to interact with peptide-antigen cross-presented on the surface of antigen-presenting cells in a major histocompatibility complex (MHC) class I-restricted fashion. (
  • The first consists of an antigen-dependent clonal proliferation, and the second of a capability to maintain for a very long time (sometimes throughout life) a population of derived cells able to proliferate again on the occasion of a further encounter with the same antigen. (
  • Only a few cells survive and enter the third stage, called "memory," during which they tend to persist and self-renew, ready to encounter the same antigen to which they had been previously exposed [ 5 ]. (
  • 3-6 Although pattern recognition receptors of innate immunity account for cholesterol uptake and contribute to activation of macrophages and endothelial cells, antigen-specific T cells recognizing low-density lipoprotein (LDL) particles in the intima provide strong proinflammatory stimuli that accelerate atherogenesis. (
  • found that expression of TRPM7 in B cells controlled actin dynamics and prevented antigen internalization. (
  • An inhibitor of TRPM7 ion channel activity reduced antigen presentation to T cells. (
  • However, the induction and expansion of T(regs) at sites of mucosal inflammation are not yet fully understood and may involve antigen presentation by local dendritic cells (DCs) and/or intestinal epithelial cells (IECs). (
  • Although gut-associated DCs can induce antigen-specific CD4(+)Foxp3(+) T cell proliferation, in vivo depletion of DCs did not preclude proliferation of these cells. (
  • Ki-67 detects a nuclear antigen associated with cell proliferation not found in resting cells. (
  • Vol 5: Large T Antigen-Specific Cytotoxic T Cells Protect Against Dendritic Cell Tumors through Perforin-Mediated Mechanisms Independent of CD4 T Cell Help. (
  • Using the poorly immunogenic B16-OVA melanoma cells as tumor model, we tested different combinations of adjuvants and antigens to treat established tumors. (
  • However, administering a combination of anti-CD40 plus TLR3 and TLR7 ligands, together with antigen targeting to dendritic cells through TLR4, was sufficient to induce tumor rejection in 50% of mice. (
  • This therapy activated T-cell responses not only against OVA, which conferred protection against a rechallenge with B16-OVA cells, but also activated T-cell responses against other melanoma-associated antigens. (
  • However, tumors usually behave as poorly immunogenic for T cells, because as opposed to professional antigen presenting cells such as dendritic cells (DC), they express low levels of antigens, MHC, and costimulatory molecules ( 2 ). (
  • Therefore, to overcome the low tumor immunogenicity, new therapeutic strategies are based on the use of adjuvants (molecules able to induce DC maturation) with or without exogenously added tumor antigens, which will activate DC to properly present tumor antigens to T cells and trigger their effector functions ( 5 ). (
  • Similarly, PCs resulting from the antigen-independent differentiation of memory B cells in vitro were inhibited by FcγRIIB cross-linking but memory B cell activation itself, as measured by proliferation, was unaffected. (
  • These results suggest a mechanism to control antibody levels involving the differential expression of FcγRIIB on B cell subpopulations, in which the FcγRIIB functions independently of the BCR to eliminate antibody-secreting effector cells and inhibit naïve B cell proliferation without compromising the long-lived antigen-specific memory B cells. (
  • Importantly, FcγRIIB requires Btk and p38 MAPK to mediate antigen-independent inhibition in human B cells. (
  • Thus, the FcγRIIB has the ability to block both the BCR-dependent, antigen-driven activation of B cells as well as antigen-independent, BCR-independent B cell activation. (
  • There is considerable evidence that the BCR-dependent FcγRIIB inhibitory pathway plays an important role in regulating the antigen-driven activation of naïve B cells to proliferate and differentiate to PCs [ 12 ]. (
  • Here we investigate the ability of the BCR-independent FcγRIIB inhibitory pathway to directly inhibit human peripheral blood PCs and to block the antigen-independent activation of human naïve and memory B cells to proliferate and differentiate into PCs in vitro . (
  • IgG-switched memory B cells in IL-6 knock-in mice displayed a diverse antibody repertoire and high specificity against immunized antigen. (
  • 2 ⇓ - 4 However, the generation of class-switched, antigen-specific antibody responses by human B cells is still a major challenge. (
  • In the absence of cognate antigen, the IgE BCR promoted terminal differentiation of B cells into plasma cells (PCs) under cell culture conditions mimicking T cell help. (
  • Instead, IgE + GC B cells exhibited poor antigen presentation and prolonged cell cycles, suggesting reduced competition for T cell help. (
  • Epidermal Langerhans cells (LC) 1 belong to the dendritic cell (DC) family and are potent antigen-presenting cells located in the suprabasal layers of the epidermis ( 3 , 30 , 36 ). (
  • After antigen uptake, LC leave the epidermis and migrate into dermis, where they travel via afferent lymphatics into the regional lymph nodes to present antigen to T cells ( 9 , 26 ). (
  • The exogenous pathway is utilized by specialized antigen-presenting cells to present peptides derived from proteins that the cell has endocytosed. (
  • Not all antigen-presenting cells utilize cross-presentation. (
  • Delta like-1 (Dlk1)/preadipocyte factor-1 (Pref-1)/fetal antigen-1 (FA1) is a novel surface marker for embryonic chondroprogenitor cells undergoing lineage progression from proliferation to prehypertrophic stages. (
  • Fully efficient cellular transformation depends on at least three independent functions of LT: binding to the retinoblastoma protein (pRB) tumor suppressor ( 14 ) and other members of this family ( 19 , 22 ), binding to the p53 tumor suppressor ( 33 , 37 ), and maintaining the integrity of the first exon (amino acids 1 to 82). (
  • Streptococcus pneumoniae has multiple protein antigens on the surface in addition to the serotype specific polysaccharide capsule antigen. (
  • The objective of the present study was to identify TAP-independent ligands from HIV gp160 protein. (
  • The protein marker in the Rh group of antigens that stimulates the greatest immune response. (
  • In contrast the pre-selection TCR repertoire from which the mature repertoire is selected includes both MHC-restricted TCRs specific for peptide-MHC (pMHC) ligands as well as MHC-independent TCRs specific for conformational epitopes on native protein ligands ( 8 ). (
  • in contrast, MHC-independent TCRs bind to intra-thymic protein ligands independently of CD4/CD8 coreceptors and so cannot access coreceptor-associated Lck to signal positive selection ( 9 ). (
  • In conclusion, our data show that T-cell function is sensitive toward the multikinase inhibitor sorafenib in a mitogen-activated protein kinase-independent fashion. (
  • Protein antigen contains a sequence within a region between 31 and 210 of the human IGF2R protein. (
  • Heterodimers between MHC-I heavy chain and β 2 m associate with the lectin chaperone calreticulin and a pre-existing complex of the transporter associated with antigen processing (TAP), the TAP-associated protein tapasin and the ERp57, forming together the peptide loading complex (PLC). (
  • In this study, we demonstrated that sperm protein 17 (Sp17) is a potential tumor antigen in myeloma. (
  • Transporter associated with antigen processing (TAP), a protein that spans the membrane of the rough endoplasmic reticulum , transports the peptides into the lumen of the rough endoplasmic reticulum (ER). (
  • It was recently shown, in mice, that long-lived bone marrow PCs express the FcγRIIB and that engaging the FcγRIIB by ICs induces these bone marrow PCs to undergo antigen-independent apoptosis [ 13 ]. (
  • This article is from Frontiers in Immunology, volume 5.AbstractOur newly generated murine tumor dendritic cell MuTuDC lines, generated from tumors developing in transgenic mice expressing the simian virus 40 large T antigen SV40LgT and GFP under the DC specific promoter CD11c, reproduce the phenotypic and functional properties of splenic wild type CD8α+ conventional DCs. (
  • Since whole microorganisms are complex structures, vaccines may contain 10 or more distinct antigens, of which generally not more than one or two engender a protective antibody. (
  • The nature of vaccines (either humoral antibody immunity inducing or cell-mediated immunity inducing) depends on the location (extracellular or intracellular) and the expression of the antigens selected for incorporation. (
  • To maintain the synergism between the kind of immunity conferred by the vaccines and the cellular location of the included antigens, new findings are gathered about the virulence factors such as toxins, adhesins, invasins (mostly enzymes), anti-apoptotic factors, anti-phagocytic factors, and many more molecules that aid in pathogenesis and invasiveness. (
  • Cancer antigens are used in clinical medicine to screen body fluids for tumors or to follow the response of tumors to treatment. (
  • To investigate the immune response toward the large T antigen that leads to rejection of the MuTuDC lines, they were genetically engineered by lentiviral transduction to express luciferase and tested for the induction of DC tumors after adoptive transfer in various gene deficient recipient mice. (
  • Low antigen expression and an absence of coimmunostimulatory signals may be partly responsible for the low immunogenicity of many tumors. (
  • Our findings support the concept that multiple adjuvant combination and antigen targeting may be a useful immunotherapeutic strategy against poorly immunogenic tumors. (
  • One of the most critical properties of this group of antigens is their ability to deliver prolonged and persistent signaling to the B cell. (
  • Human Leukocyte Antigen and Systemic Sclerosis in Japanese: The Sign of the Four Independent Protective Alleles, DRB1*13:02, DRB1*14:06, DQB1*03:01. (
  • Several studies on associations between human leukocyte antigen (HLA) allele frequencies and susceptibility to systemic sclerosis (SSc) have been reported. (
  • There was an absolute requirement for the presentor cell to be class II+, and the activation signal on mitogen-treated class II+ presentor could be blocked by monoclonal antibody to the class II antigens. (
  • mAb reactive with CD4 inhibited CD4-gamma 3-induced adhesion and a mutant B lymphoblastoid cell line deficient in class II antigens failed to respond. (
  • Consistent with this, homotypic adhesion induced by engagement of MHC class II antigens was observed with LFA-1-deficient B cell lines, and was independent of CD49d or CD18 expression. (
  • Thus, the direct engagement of B cell class II antigens by CD4 is likely to generate transmembrane signals which trigger both LFA-1-dependent and LFA-1-independent adhesion pathways. (
  • Pathogenic autoantibodies can protect or cause diseases via neutralization of self-antigens, opsonization, antibody-dependent cellular cytotoxicity, activation of the complement system, pro-inflammatory and anti-inflammatory effect. (
  • Cellular immunity appears also to be targeted, but it remains unclear whether it is specific to LDL antigens. (
  • However, in CD4/CD8 coreceptor-deficient mice, Lck in immature thymocytes is not sequestered by coreceptors and so is available to transduce signals from all ligand-engaged TCRs, including TCRs specific for MHC-independent ligands. (
  • They recognize their ligands in a non-MHC restricted way and, as part of the innate immunity, are generally considered unable to remember antigens and to increase the magnitude of their response over time [ 3 ]. (
  • Individuals with nonfunctional transporters associated with antigen processing (TAP) complexes are not particularly susceptible to viral infections or neoplasms. (
  • Therefore, their immune system must be reasonably efficient, and the present, though reduced, cytolytic CD8 + αβ T subpopulation specific for TAP-independent antigens may be sufficient to establish an immune defense protecting against viral infections in these individuals. (
  • They feature both the need to recognize the antigen and the ability to arouse a faster and stronger response when they encounter their cognate antigen for a second time. (
  • Apoptosis induction seems to be mediated either by stimulation of BAX and FAS antigen expression, or by repression of Bcl-2 expression. (
  • Suboptimal stimulation of B cell lines through HLA-D antigens induced homotypic adhesion that was dependent on the activation of LFA-1 (CD11a/CD18), and which could be blocked by specific mAb. (
  • They are based on the use of DC pulsed or expressing different types of antigens ( 14-16 ) or complex immunogens such as recombinant viruses, bacteria, or virus-like particles which contain many DC-activating signals ( 17-19 ). (
  • In this review we have attempted to define the characteristics of TI-2 antigens that enable them to stimulate antibody production in the absence of T cell help. (
  • Antibody diversity is first generated by rearrangement of immunoglobulin (Ig) genes during B cell development in the bone marrow, and later by antigen-driven diversification in germinal centers (GCs). (
The 3BP2 Adapter Protein Is Required for Optimal B-Cell Activation and Thymus-Independent Type 2 Humoral Response | Molecular...
The 3BP2 Adapter Protein Is Required for Optimal B-Cell Activation and Thymus-Independent Type 2 Humoral Response | Molecular... (
Antigen Testing Is Here. But There's a Catch. - Mother Jones
Antigen Testing Is Here. But There's a Catch. - Mother Jones (
Antigen - Wikipedia
Antigen - Wikipedia (
Identification of dendritic antigen-presenting cells in the zebrafish | PNAS
Identification of dendritic antigen-presenting cells in the zebrafish | PNAS (
Rapid antigen tests strengthen fight against COVID-19, say experts
Rapid antigen tests strengthen fight against COVID-19, say experts (
What is the role of food antigens in the etiology of atopic dermatitis (eczema)?
What is the role of food antigens in the etiology of atopic dermatitis (eczema)? (
Circadian clock cryptochrome proteins regulate autoimmunity | PNAS
Circadian clock cryptochrome proteins regulate autoimmunity | PNAS (
Distinct functions of antigen-specific CD4 T cells during murine Mycobacterium tuberculosis infection | PNAS
Distinct functions of antigen-specific CD4 T cells during murine Mycobacterium tuberculosis infection | PNAS (
Code System: CDCNHSN  | NHSN | CDC
Code System: CDCNHSN | NHSN | CDC (
A chemical biology toolbox to study protein methyltransferases and epigenetic signaling | Nature Communications
A chemical biology toolbox to study protein methyltransferases and epigenetic signaling | Nature Communications (
Frontiers | Cernunnos/Xlf Deficiency Results in Suboptimal V(D)J Recombination and Impaired Lymphoid Development in Mice |...
Frontiers | Cernunnos/Xlf Deficiency Results in Suboptimal V(D)J Recombination and Impaired Lymphoid Development in Mice |... (
The HTLV-I Tax Protein Transcriptionally Modulates OX40 Antigen Expression | The Journal of Immunology
The HTLV-I Tax Protein Transcriptionally Modulates OX40 Antigen Expression | The Journal of Immunology (
Potassium channels Kv1.3 and KCa3.1 cooperatively and compensatorily regulate antigen-specific memory T cell functions | Nature...
Potassium channels Kv1.3 and KCa3.1 cooperatively and compensatorily regulate antigen-specific memory T cell functions | Nature... (
MAPK-independent impairment of T-cell responses by the multikinase inhibitor sorafenib | Molecular Cancer Therapeutics
MAPK-independent impairment of T-cell responses by the multikinase inhibitor sorafenib | Molecular Cancer Therapeutics (
Immortalized Myeloid Suppressor Cells Trigger Apoptosis in Antigen-Activated T Lymphocytes | The Journal of Immunology
Immortalized Myeloid Suppressor Cells Trigger Apoptosis in Antigen-Activated T Lymphocytes | The Journal of Immunology (
Hypoxia-Inducible Factor Regulates Survival of Antigen Receptor-Driven T Cells | The Journal of Immunology
Hypoxia-Inducible Factor Regulates Survival of Antigen Receptor-Driven T Cells | The Journal of Immunology (
The role of surface IgD in the response to thymic-independent antigens. | JEM
The role of surface IgD in the response to thymic-independent antigens. | JEM (
Intraepithelial CD8+ tumor-infiltrating lymphocytes and a high CD8+/regulatory T cell ratio are associated with favorable...
Intraepithelial CD8+ tumor-infiltrating lymphocytes and a high CD8+/regulatory T cell ratio are associated with favorable... (
Preventing Pneumococcal Disease Among Infants and Young Children
Preventing Pneumococcal Disease Among Infants and Young Children (
Prevention and Control of Meningococcal Disease
Prevention and Control of Meningococcal Disease (
B cell receptor ligation induces display of V-region peptides on MHC class II molecules to T cells | PNAS
B cell receptor ligation induces display of V-region peptides on MHC class II molecules to T cells | PNAS (
A Plant-Produced Antigen Elicits Potent Immune Responses against West Nile Virus in Mice
A Plant-Produced Antigen Elicits Potent Immune Responses against West Nile Virus in Mice (
Low-Dose Antigen Promotes Induction of FOXP3 in Human CD4+ T Cells | The Journal of Immunology
Low-Dose Antigen Promotes Induction of FOXP3 in Human CD4+ T Cells | The Journal of Immunology (
T-cell triggering thresholds are modulated by the number of antigen within individual T-cell receptor clusters | PNAS
T-cell triggering thresholds are modulated by the number of antigen within individual T-cell receptor clusters | PNAS (
Dynahead - Antigen  - The Rocktologist
Dynahead - Antigen - The Rocktologist (
Anti-IGF-II R/Mannose 6 Phosphate Receptor (Cation independent), Polyclonal,
 | Fisher Scientific
Anti-IGF-II R/Mannose 6 Phosphate Receptor (Cation independent), Polyclonal, | Fisher Scientific (
Frontiers | Activated Mesenchymal Stromal Cells Process and Present Antigens Regulating Adaptive Immunity | Immunology
Frontiers | Activated Mesenchymal Stromal Cells Process and Present Antigens Regulating Adaptive Immunity | Immunology (
Aging of cell membrane molecules: Band 3 and senescent cell antigen in neural tissue | SpringerLink
Aging of cell membrane molecules: Band 3 and senescent cell antigen in neural tissue | SpringerLink (
Gut homeostasis and regulatory T cell induction depend on molecular chaperone gp96 in CD11c + cells | Scientific Reports
Gut homeostasis and regulatory T cell induction depend on molecular chaperone gp96 in CD11c + cells | Scientific Reports (
MAGE cancer-testis antigens protect the mammalian germline under environmental stress | Science Advances
MAGE cancer-testis antigens protect the mammalian germline under environmental stress | Science Advances (
Prevention and Control of Meningococcal Disease
Prevention and Control of Meningococcal Disease (