Clonal Evolution: The process of accumulation of genetic and epigenetic changes over time in individual cells and the effect of the changes on CELL PROLIFERATION.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)Selection, Genetic: Differential and non-random reproduction of different genotypes, operating to alter the gene frequencies within a population.Antigens: Substances that are recognized by the immune system and induce an immune reaction.Clonal Selection, Antigen-Mediated: LYMPHOCYTE ACTIVATION by a specific ANTIGEN thus triggering clonal expansion of LYMPHOCYTES already capable of mounting an immune response to the antigen.Antigens, Bacterial: Substances elaborated by bacteria that have antigenic activity.Clonal Deletion: Removal, via CELL DEATH, of immature lymphocytes that interact with antigens during maturation. For T-lymphocytes this occurs in the thymus and ensures that mature T-lymphocytes are self tolerant. B-lymphocytes may also undergo clonal deletion.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.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.Immunoglobulin Variable Region: That region of the immunoglobulin molecule that varies in its amino acid sequence and composition, and comprises the binding site for a specific antigen. It is located at the N-terminus of the Fab fragment of the immunoglobulin. It includes hypervariable regions (COMPLEMENTARITY DETERMINING REGIONS) and framework regions.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.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.Antigens, Viral: Substances elaborated by viruses that have antigenic activity.Immunoglobulin Heavy Chains: The largest of polypeptide chains comprising immunoglobulins. They contain 450 to 600 amino acid residues per chain, and have molecular weights of 51-72 kDa.Genes, Immunoglobulin: Genes encoding the different subunits of the IMMUNOGLOBULINS, for example the IMMUNOGLOBULIN LIGHT CHAIN GENES and the IMMUNOGLOBULIN HEAVY CHAIN GENES. The heavy and light immunoglobulin genes are present as gene segments in the germline cells. The completed genes are created when the segments are shuffled and assembled (B-LYMPHOCYTE GENE REARRANGEMENT) during B-LYMPHOCYTE maturation. The gene segments of the human light and heavy chain germline genes are symbolized V (variable), J (joining) and C (constant). The heavy chain germline genes have an additional segment D (diversity).Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.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.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.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Cell Transformation, Neoplastic: Cell changes manifested by escape from control mechanisms, increased growth potential, alterations in the cell surface, karyotypic abnormalities, morphological and biochemical deviations from the norm, and other attributes conferring the ability to invade, metastasize, and kill.Karyotyping: Mapping of the KARYOTYPE of a cell.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Antigens, Protozoan: Any part or derivative of any protozoan that elicits immunity; malaria (Plasmodium) and trypanosome antigens are presently the most frequently encountered.Mice, Inbred C57BLCell Line: Established cell cultures that have the potential to propagate indefinitely.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.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.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.Cell Differentiation: Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.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.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.H-2 Antigens: The major group of transplantation antigens in the mouse.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.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.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.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.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.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.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.Epitopes: Sites on an antigen that interact with specific antibodies.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.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.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)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.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.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.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.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).Models, Genetic: Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Immunoglobulin G: The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.Cross Reactions: Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.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.Mice, Inbred BALB CEvolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.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.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.Lymphocyte 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.Genetic Variation: Genotypic differences observed among individuals in a population.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.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.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.Receptors, Antigen: Molecules on the surface of B- and T-lymphocytes that recognize and combine with specific antigens.Biological Evolution: The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.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.Antigen-Antibody Reactions: The processes triggered by interactions of ANTIBODIES with their ANTIGENS.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.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.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.Antibody Formation: The production of ANTIBODIES by proliferating and differentiated B-LYMPHOCYTES under stimulation by 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.Antibodies, Bacterial: Immunoglobulins produced in a response to BACTERIAL ANTIGENS.Selection Bias: The introduction of error due to systematic differences in the characteristics between those selected and those not selected for a given study. In sampling bias, error is the result of failure to ensure that all members of the reference population have a known chance of selection in the sample.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).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.Patient Selection: Criteria and standards used for the determination of the appropriateness of the inclusion of patients with specific conditions in proposed treatment plans and the criteria used for the inclusion of subjects in various clinical trials and other research protocols.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.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.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.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.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.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.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.Autoantigens: Endogenous tissue constituents that have the ability to interact with AUTOANTIBODIES and cause an immune response.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.Spleen: An encapsulated lymphatic organ through which venous blood filters.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.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).Genetics, Population: The discipline studying genetic composition of populations and effects of factors such as GENETIC SELECTION, population size, MUTATION, migration, and GENETIC DRIFT on the frequencies of various GENOTYPES and PHENOTYPES using a variety of GENETIC TECHNIQUES.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Alleles: Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.Antigens, Heterophile: Antigens stimulating the formation of, or combining with heterophile antibodies. They are cross-reacting antigens found in phylogenetically unrelated species.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.Hepatitis B Core Antigens: The hepatitis B antigen within the core of the Dane particle, the infectious hepatitis virion.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.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.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.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)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.Molecular Weight: The sum of the weight of all the atoms in a molecule.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.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.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.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.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.Recombinant Proteins: Proteins prepared by recombinant DNA technology.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).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.Ovalbumin: An albumin obtained from the white of eggs. It is a member of the serpin superfamily.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.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.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.Mice, Transgenic: Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.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.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.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.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.Antibodies, Viral: Immunoglobulins produced in response to VIRAL ANTIGENS.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.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.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.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.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.Peptide Library: A collection of cloned peptides, or chemically synthesized peptides, frequently consisting of all possible combinations of amino acids making up an n-amino acid peptide.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.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.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.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.Bacterial Proteins: Proteins found in any species of bacterium.Antibodies, Protozoan: Immunoglobulins produced in a response to PROTOZOAN ANTIGENS.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.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.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.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.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.gp100 Melanoma Antigen: A melanosome-associated protein that plays a role in the maturation of the MELANOSOME.CA-19-9 Antigen: Sialylated Lewis blood group carbohydrate antigen found in many adenocarcinomas of the digestive tract, especially pancreatic tumors.Mating Preference, Animal: The selection or choice of sexual partner in animals. Often this reproductive preference is based on traits in the potential mate, such as coloration, size, or behavioral boldness. If the chosen ones are genetically different from the rejected ones, then NATURAL SELECTION is occurring.Hemagglutination Tests: Sensitive tests to measure certain antigens, antibodies, or viruses, using their ability to agglutinate certain erythrocytes. (From Stedman, 26th ed)Recombination, Genetic: Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.Serologic Tests: Diagnostic procedures involving immunoglobulin reactions.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.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.Autoantibodies: Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.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.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.Antigens, T-Independent: Antigens which may directly stimulate B lymphocytes without the cooperation of T lymphocytes.Algorithms: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.Genetic Vectors: DNA molecules capable of autonomous replication within a host cell and into which other DNA sequences can be inserted and thus amplified. Many are derived from PLASMIDS; BACTERIOPHAGES; or VIRUSES. They are used for transporting foreign genes into recipient cells. Genetic vectors possess a functional replicator site and contain GENETIC MARKERS to facilitate their selective recognition.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.Antibodies, Helminth: Immunoglobulins produced in a response to HELMINTH ANTIGENS.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.Plasmids: Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.Membrane Glycoproteins: Glycoproteins found on the membrane or surface of cells.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.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)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.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.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.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).DNA: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).Genetic Drift: The fluctuation of the ALLELE FREQUENCY from one generation to the next.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.Hypersensitivity, Delayed: An increased reactivity to specific antigens mediated not by antibodies but by cells.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.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.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.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.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.Adaptation, Biological: Changes in biological features that help an organism cope with its ENVIRONMENT. These changes include physiological (ADAPTATION, PHYSIOLOGICAL), phenotypic and genetic changes.Gene Frequency: The proportion of one particular in the total of all ALLELES for one genetic locus in a breeding POPULATION.Antigens, Nuclear: Immunologically detectable substances found in the CELL NUCLEUS.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.Prostatic Neoplasms: Tumors or cancer of the PROSTATE.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.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.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Hepatitis delta Antigens: Antigens produced by various strains of HEPATITIS D VIRUS.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.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.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Crosses, Genetic: Deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent. The parent organisms must be genetically compatible and may be from different varieties or closely related species.Glycoproteins: Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.Inbreeding: The mating of plants or non-human animals which are closely related genetically.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.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.Polysaccharides, Bacterial: Polysaccharides found in bacteria and in capsules thereof.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.HLA-DR4 Antigen: An HLA-DR antigen which is associated with HLA-DRB1 CHAINS encoded by DRB1*04 alleles.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.Reproduction: The total process by which organisms produce offspring. (Stedman, 25th ed)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.

BAFF and selection of autoreactive B cells. (1/35)

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Unifying concepts of MHC-dependent natural killer cell education. (2/35)

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Regulated release of nitric oxide by nonhematopoietic stroma controls expansion of the activated T cell pool in lymph nodes. (3/35)

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The carboxypeptidase ACE shapes the MHC class I peptide repertoire. (4/35)

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Mucosal memory CD8(+) T cells are selected in the periphery by an MHC class I molecule. (5/35)

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Coreceptor gene imprinting governs thymocyte lineage fate. (6/35)

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Elongation factor-2, a Th1 stimulatory protein of Leishmania donovani, generates strong IFN-gamma and IL-12 response in cured Leishmania-infected patients/hamsters and protects hamsters against Leishmania challenge. (7/35)

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HLA B*5701-positive long-term nonprogressors/elite controllers are not distinguished from progressors by the clonal composition of HIV-specific CD8+ T cells. (8/35)

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Here are some very clear clips for the immune responses to infection, starting with a really well done explanation of Burnets Nobel-winning clonal selection theory: If you like that, check out some more of the videos from the Walter and Eliza Hall Institute of Medical Research. Try this animation and quiz: McGraw Hill Online Centre…
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... in support of Burnet's clonal selection theory. In 1968 Ada was appointed head of the Microbiology Department at the John ... From 1962 he focused on immune reactions, demonstrating that antigens are not present in antibody-producing cells, ... during his period of leadership the school became an international centre for the analysis of T cell-mediated immunity. He was ...
Mimotope Tumor antigen Antigen-antibody interaction Immunogenetics Affinity maturation Somatic hypermutation Clonal selection V ... Antibody-dependent cell-mediated cytotoxicity (ADCC) Foreign Pernicious anemia Hemolytic disease of the newborn Autoimmune ... Tolerance Central tolerance Peripheral tolerance Clonal anergy Clonal deletion Tolerance in pregnancy Immunodeficiency Antigen ... T cells Antigen receptor - T cell receptor (TCR) Subunits - [email protected] / [email protected] / [email protected] / [email protected] Co-receptors CD8 (CD8α / CD8β) CD4 ...
Myriad receptors are produced through a process known as clonal selection. According to the clonal selection theory, at birth, ... Coating antigen with antibody enhances phagocytosis Antibody-dependent cell-mediate cytotoxicity: Antibodies attached to target ... This theory, which builds on established concepts of clonal selection, is being applied in the search for an HIV vaccine. ... Once activated, the CTL undergoes a process called clonal selection, in which it gains functions and divides rapidly to produce ...
Clonal anergy Clonal deletion Clonal selection Clone (cell biology) CMKLR1 Colony stimulating factor 1 receptor Colony- ... opsonization Antibody-dependent cell-mediated cytotoxicity Antibody-dependent enhancement Antigen Antigen presentation Antigen ... DAMPs Danger model Defensin Degranulation Dendritic cell Dextran 1 Dispanin Dog leukocyte antigen Drug resistance Duffy antigen ... antitumor immunity CD74 CD94/NKG2 Cell-mediated immunity CELSR1 Central tolerance Chemokine Chemokine receptor Chimeric antigen ...
This high mutation rate makes them prone to the selection of B-cells lacking the CD20 antigen following treatment with CD20- ... A study of DLBCL cell lines indicated that 14-3-3ζ proteins may play a role in mediating resistance of DLBCL cells to CHOP. 14- ... Clonal B-cells spontaneously mutate the idiotypic region of their immunoglobulin. ... B-cells that have not encountered an antigen are called naive B cells. When naïve B-cells encounter an antigen, one of the ...
This idea is known as Clonal Selection Theory. At the time, many leading scientists including Linus Pauling and James Watson ... Compatibility genes were essential in immune system mediated viral clearing. The pair coined the term "MHC Restriction" to ... The Hu-1 antigens were renamed the Human-lymphoid (HL) allo-antigens (HL-As). Allo-antigen comes from the observation that a ... Human leukocyte antigens (HLA) began as a list of antigens identified as a result of transplant rejection. The antigens were ...
This antigen induced loss of cells from the B cell repertoire is known as clonal deletion. B cells may encounter two types of ... Positive selection occurs in the thymic cortex. This process is primarily mediated by thymic epithelial cells, which are rich ... Thus, positive selection ensures that T cells only recognize antigen in association with MHC. This is important because one of ... This leads to a lack of expression of peripheral antigens in the thymus, and hence a lack of negative selection towards key ...
1984). "From an antigen-centered, clonal perspective of immune responses to an organism-centered network perspective of ... In the mid-1950s, Macfarlane Burnet, inspired by a suggestion made by Niels Jerne, formulated the clonal selection theory (CST ... Symbiont-mediated defenses are also heritable across host generations, despite a non-genetic direct basis for the transmission ... Burnet FM (1959). The Clonal Selection Theory of Acquired Immunity. Cambridge: Cambridge University Press. Burnet FM (1969). ...
Clonal selection[edit]. For more details on lymph nodes, germinal centers of lymph nodes and clonal selection of B cells, see ... Steps in production of antibodies by B cells: 1. Antigen is recognized and engulfed by B cell 2. Antigen is processed 3. ... The role of lymphocytes in mediating both cell-mediated and humoral responses was demonstrated by James Gowans in 1959.[30] ... The clonal selection theory was proved correct when Sir Gustav Nossal showed that each B cell always produces only one antibody ...
1984). "From an antigen-centered, clonal perspective of immune responses to an organism-centered network perspective of ... In the mid-1950s, Frank Burnet, inspired by a suggestion made by Niels Jerne, formulated the clonal selection theory (CST) of ... B cells are involved in the humoral immune response, whereas T cells are involved in cell-mediated immune response. Both B ... antigens during a process called antigen presentation. Antigen specificity allows for the generation of responses that are ...
Negative selection occurs through the binding of self-antigen with the BCR; If the BCR can bind strongly to self-antigen, then ... Upon antigen binding, the memory B cell takes up the antigen through receptor-mediated endocytosis, degrades it, and presents ... the B cell undergoes one of four fates: clonal deletion, receptor editing, anergy, or ignorance (B cell ignores signal and ... Once a BCR binds a TD antigen, the antigen is taken up into the B cell through receptor-mediated endocytosis, degraded, and ...
... allowing for more clonal selection of the immunodominant T cells over the subdominant T cells. Immunodominant T cells also ... Antigen-presenting cells such as dendritic cells, can have up to six different types of MHC molecules for antigen presentation ... Immunodominance is evident for both antibody-mediated immunity and cell-mediated immunity. Epitopes that are not targeted or ... Antigens from a particular pathogen can be of variable immunogenicity, with the antigen that stimulates the strongest response ...
... is known as clonal anergy. The mechanism of clonal anergy is important to maintain tolerance to many autologous antigens. ... This negative selection is known as clonal deletion, one of the mechanisms for B cell tolerance. Approximately 0.99 percent of ... Autoreactive T cells are activated de novo by self epitopes released secondary to pathogen-specific T cell-mediated bystander ... Cells that survive positive selection, but bind strongly to self-antigens are negatively selected also by active induction of ...
Negative selection in the medulla then obliterates T cells that bind too strongly to self-antigens expressed on MHC molecules. ... Increasing evidence indicates microRNAs, which are small noncoding regulatory RNAs, could impact the clonal selection process ... A T cell, or T lymphocyte, is a type of lymphocyte (a subtype of white blood cell) that plays a central role in cell-mediated ... Antigen-naïve T cells expand and differentiate into memory and effector T cells after they encounter their cognate antigen ...
Nature 338, 591 (1989). Essential role of T cell receptor-mediated positive selection in T cell survival and lineage fate (CD4/ ... Teho H. S., Kisielow, P., Scott, 8., Kishi, H., Uematsu, Y., Blüthmann, H. and von Boehmer, H.: Thymic MHC antigens and the ... Nature 333, 742-746 (1988); Swat, W., Ignatowicz, L., von Boehmer, H. and Kisielow, P.: Clonal deletion of immature CD4+8+ ... Questions concerned with the role of positive and negative selection of developing T cells by peptide-MHC complexes in the ...
Affinity-based selection of regulatory T cells occurs independent of agonist-mediated induction of Foxp3 expression. „J Immunol ... Selection of Foxp3+ regulatory T cells specific for self antigen expressed and presented by Aire+ medullary thymic epithelial ... B7/CD28 in central tolerance: costimulation promotes maturation of regulatory T cell precursors and prevents their clonal ... Steady state migratory RelB+ langerin+ dermal dendritic cells mediate peripheral induction of antigen-specific CD4+ CD25+ ...
... which expand in response to specific antigen (process called "clonal selection"). This specific clonal army then combats the ... De Flora, S.; Grassi, C.; Carati, L. (1997). "Attenuation of influenza-like symptomatology and improvement of cell-mediated ... Thus when an antigen is properly presented to the T lymphocytes by an antigen presenting cell (APC), which displays the antigen ... However, when T cells interacts with an antigen not presented by the APCs, that is very probably not the antigen that an immune ...
Negative selection in the medulla then obliterates T cells that bind too strongly to self-antigens expressed on MHC molecules. ... "Disappearance of T Cell-Mediated Rejection Despite Continued Antibody-Mediated Rejection in Late Kidney Transplant Recipients" ... Virtual memory T cells differ from the other memory subsets in that they do not originate following a strong clonal expansion ... Negative selectionEdit. Negative selection removes thymocytes that are capable of strongly binding with "self" MHC peptides. ...
MAIT cells can be activated in ways that involve, and do not involve, MR1-mediated antigen presentation. However, MR1- ... they may also undergo clonal expansion in the periphery and establish antigen memory. In this way, MAIT cells display both ... T cells rearrange their TCRs and are subjected to TCR affinity tests as a part of positive selection and negative selection. ... A chemically stable antigen that is functionally equivalent to the native vitamin B2 related antigen has been created. Like MHC ...
... and undergo clonal expansion to produce a foci of B cells that are specific for the antigen. Most of these clones differentiate ... It is unclear at what stage such a model reaches saturation to provide an optimal level of antibody-mediated immune protection ... germinal center B cells are subjected to a round of selection by TFH cells. B cell clones that have mutated and gained higher ... With each such subsequent exposure to the same antigen, the number of different responding B cell clones increases to generate ...
Negative selection in the medulla then obliterates T cells that bind too strongly to self-antigens expressed on MHC molecules. ... Increasing evidence indicates microRNAs, which are small noncoding regulatory RNAs, could impact the clonal selection process ... A T cell, or T lymphocyte, is a type of lymphocyte (a subtype of white blood cell) that plays a central role in cell-mediated ... Positive selection[edit]. Positive selection "selects for" T cells capable of interacting with MHC. Positive selection involves ...
Within germinal centers, TFH cells play a critical role in mediating the selection and survival of B cells that go on to ... In germinal centers, antigen-experienced TFH cells rapidly upregulate the expression of CD40L, which binds and stimulates the B ... causes B cell antibodies to class switch from IgM/IgD to other antibody isotypes and drives somatic hypermutation during clonal ... Follicular B helper T cells (also known as just follicular helper T cells or TFH), are antigen-experienced CD4+ T cells found ...
negative selection, in which those double-positive T cells that bind too strongly to MHC-presented self antigens undergo ... Once activated, the TC cell undergoes clonal expansion with the help of the cytokine Interleukin-2 (IL-2), which is a growth ... "Platelets mediate cytotoxic T lymphocyte-induced liver damage". Nature Medicine. 11 (11): 1167-9. doi:10.1038/nm1317. PMC ... An antigen is a molecule capable of stimulating an immune response, and is often produced by cancer cells or viruses. Antigens ...
clonal selection . cloning The process of producing similar populations of genetically identical individuals that occurs in ... which act as a critical part of the immune response by specifically recognizing and binding to particular antigens, such as ... cells of the nervous system and the organization of these cells into functional circuits that process information and mediate ... artificial selection Professionals study the genotype and phenotype of parent organisms in the hope of producing a hybrid that ...
In the mid-1950s, Macfarlane Burnet, inspired by a suggestion made by Niels Jerne,[41] formulated the clonal selection theory ( ... Coutinho A, Forni L, Holmberg D, Ivars F, Vaz N (1984). "From an antigen-centered, clonal perspective of immune responses to an ... Symbiont-mediated defenses are also heritable across host generations, despite a non-genetic direct basis for the transmission ... Burnet FM (1959). The Clonal Selection Theory of Acquired Immunity. Cambridge: Cambridge University Press.. ...
... and internalizes offending antigens, which are taken up by the B cell through receptor-mediated endocytosis and processed. ... by selection for the ability to bind antigen with higher affinity, the activation and growth of B cell clones able to secrete ... Surface antigens[edit]. Terminally differentiated plasma cells express relatively few surface antigens, and do not express ... Another important surface antigen is CD319 (SLAMF7). This antigen is expressed at high levels on normal human plasma cells. It ...
Clonal Selection, Antigen-Mediated* * Humans * Leukemia* / diagnosis * Leukemia* / immunology * Leukemia* / metabolism * Models ... Model results imply that enhanced self-renewal may be a key mechanism in the clonal selection process. Simulations suggest that ... Clonal selection and therapy resistance in acute leukaemias: mathematical modelling explains different proliferation patterns ... We propose a new mathematical model to investigate the impact of cell properties on the multi-clonal composition of leukaemias ...
Clonal selection raises the clonal frequency of cells with a particular antigen specificity rather than all cells. This means ... Effector phase - humoural and cell-mediated immunity, elimination of antigen. Decline homeostasis - T and B cell apoptosis. ... Recognition phase - clonal selection and expansion Activation phase - differentiation to effector cells. ... Who saw the link between cell mediated and humour all immunity and when? ...
In these cases the nature of the antigen is the major variable. ... 1-8. Clonal selection of lymphocytes is the central principle ... 1-7. Lymphocytes activated by antigen give rise to clones of antigen-specific cells that mediate adaptive immunity ... Endogenous superantigens mediate negative selection of T-cell receptors derived from particular Vβ gene segments ... 3-9 Antigen-antibody interactions involve a variety of forces. *3-10 The antigen receptor on T cells is very similar to a Fab ...
This process is called clonal selection because only the TH cells that recognize the foreign invader are selected to reproduce ... The APC "shows" the antigen to the TH cells until there is a match between a TH cell receptor and the antigen. The contact ... Two parts of adaptive immunity meet this challenge: cellular-mediated immunity and humoral (antibody-mediated immunity). ... After an antigen is cleared from the body, immunological memory allows an antigen to be recognized and removed more quickly if ...
In 1957, Burnet put forth his clonal selection theory to explain the biology of immune responses. On meeting an antigen, an ... Cell-mediated immune responses involve several events following the entry of antigen. Helper T cells are required, so some of ... In 1957, Burnet put forth his clonal selection theory to explain the biology of immune responses. On meeting an antigen, an ... Few antigens bind directly to antigen-reactive T- or B-cells but are presented to the lymphocytes bound to other antigen ...
Recruitment and selection of marginal zone B cells is independent of exogenous antigens. Eur. J. Immunol. 35: 2089-2099. ... Clonal selection and learning in the antibody system. Nature 381: 751-758. ... Antigen-specific B cells efficiently present low doses of antigen for induction of T cell proliferation. J. Immunol. 135: 980- ... 3⇑E) following BCR-mediated internalization, does this result in MHC class II-mediated presentation of Salmonella Ags? To test ...
... antigen-driven clonal selection, and humoral immunity. B-cell receptor signaling activates PI3K-mediated activation of the ... Chimeric Antigen Receptor T Cells in Refractory B-Cell Lymphomas. N Engl J Med. 2017 Dec 28. 377 (26):2545-2554. [Medline]. ... Dal Porto JM, Gauld SB, Merrell KT, Mills D, Pugh-Bernard AE, Cambier J. B cell antigen receptor signaling 101. Mol Immunol. ... Thome M, Charton JE, Pelzer C, Hailfinger S. Antigen receptor signaling to NF-kappaB via CARMA1, BCL10, and MALT1. Cold Spring ...
... antigen-driven clonal selection, and humoral immunity. B-cell receptor signaling activates PI3K-mediated activation of the ... Chimeric Antigen Receptor T Cells in Refractory B-Cell Lymphomas. N Engl J Med. 2017 Dec 28. 377 (26):2545-2554. [Medline]. ... Dal Porto JM, Gauld SB, Merrell KT, Mills D, Pugh-Bernard AE, Cambier J. B cell antigen receptor signaling 101. Mol Immunol. ... Thome M, Charton JE, Pelzer C, Hailfinger S. Antigen receptor signaling to NF-kappaB via CARMA1, BCL10, and MALT1. Cold Spring ...
Cell-mediated immunity and antibody-mediated immunity. Whats clonal selection?. Process by which a lymphocyte proliferates ( ... Aka human leukocyte antigens. What is the functions of antigen presenting cells and name few?. Lymphocyte that begins ... What is MHC antigen?. Major histocompatibility complex antigen. Surface proteins on white blood cells & other nucleated cells ... Whats the difference between a complete antigen and a hapten? Give an example.. A complete antigen has both reactivity and ...
Clonal Selection Clonal Selection: Selection: B cells (and T cells) that encounter stimulating antigen will proliferate into a ... Cell Mediated Immunity is Carried Out by T Lymphocytes .. Microbes: Microbes: Capsules. etc.Antigens Most are proteins or large ... Clonal selection increases number of T cells. and reacts to a specific antigen (T cell receptor). T cells have an antigen ... Clonal Selection: Selection: When a B cell encounters an antigen it recognizes. After maturation B cells migrate to lymphoid ...
T-CELL MEDIATED IMMUNITY (cont.)*Clonal selection determines proliferation of T cells that carry out cell-mediated immunity ... CLONAL DELETION*During fetal development, clones of lymphocytes that react with self antigens are eliminated (self-tolerance) ... K antigen (acidic polysaccharides) of E. coli or the analogous Vi antigen of Salmonella typhi ... Specific Defenses of the Host: The Immune Response -Immunogen : a substance that induces a specific immune response antigen (ag ...
Antigens, antibodies, antigen receptors, antigenic determinants - Clonal selection • Effector and memory cells - Primary vs. ... Secondary infections - Lymphocytes • B-cells and T cells - Humoral immunity - Cell mediated immunity • Book problems - 1, 2, 3 ... Secondary immune response Cell mediated immunity Chapter 27 content and book questions ... Natural selection - Genetic drift, - Small population size - Gene flow between populations - Non random mating ...
... antigen-driven clonal selection, and humoral immunity. B-cell receptor signaling activates PI3K-mediated activation of the ... antigen-driven clonal selection, and humoral immunity. Structurally, the BCR consists of antigen-binding IgH and immunoglobulin ... 66] Upon antigen stimulation, clustering of the BCRs occurs, leading to signal transduction via the CD79A and B subunits. [67] ... Chimeric Antigen Receptor T Cells in Refractory B-Cell Lymphomas. N Engl J Med. 2017 Dec 28. 377 (26):2545-2554. [Medline]. ...
... antigen-driven clonal selection, and humoral immunity. B-cell receptor signaling activates PI3K-mediated activation of the ... Chimeric antigen receptor (CAR) T-cell therapy utilizes each patients own T cells, extracted by leukapheresis. The T cells are ... Dal Porto JM, Gauld SB, Merrell KT, Mills D, Pugh-Bernard AE, Cambier J. B cell antigen receptor signaling 101. Mol Immunol. ... Thome M, Charton JE, Pelzer C, Hailfinger S. Antigen receptor signaling to NF-kappaB via CARMA1, BCL10, and MALT1. Cold Spring ...
How humoral immunity works and how cell mediated immunity works. How vaccination and vaccines lead to a primary immune response ... Clonal selection. The process by which the B cells will make the right antibody to inactivate or destroy a particular pathogen ... The antigens are combined with special proteins called the major histocompatibility complex (MHC). The antigen/MHC complexes ... Cell-mediated system. The response of the immune system to body cells that have changed in some way e.g. have been infected by ...
... in which B-cell clonal selection may arise. B-cell clonal expansion starts as an antigen-driven event and expands towards ... Among them, complement factors play a crucial role in the cold-insoluble ICs-mediated vasculitis, involving primarily small ...
... developing T cells have undergone extensive selection within the thymus as well as post-thymic antigen-mediated clonal ... was not associated with clonal selection or expansion in vivo. Clonal analysis of long-term repopulating cell progeny in vivo ... Finally, it is possible that antigen-mediated skewing of the T cell repertoire would alter the representation of RISs, although ... Multilineage hematopoietic reconstitution without clonal selection in ADA-SCID patients treated with stem cell gene therapy. ...
Describe the mechanism of clonal selection. 12. Describe the cellular basis for immunological memory. 13. Describe the cellular ... and explain what happens when they are activated by antigens. 10. Explain how a single antigen molecule may stimulate the ... Explain how humoral immunity and cell-mediated immunity differ in their defensive activities. 9. Describe where T and B cells ... Recognize and bind to antigens b. Assist in destruction and elimination of antigens 16. List the five major classes of ...
The clonal selection theory implies that . antigens activate specific lymphocytes. The protection provided through transfer of ... The allergic response is primarily mediated by _____ antibodies. IgE In mammalian defenses against invading pathogens, all of ... Antigens are non-self proteins. . Which of the following is true of both T cells and B cells? All of these statements are true ... Which of the following statements about antibody-mediated immunity is CORRECT? It defends against parasites, bacteria, and ...
The enriched CD4-positive cells were subjected to limited dilution for clonal selection. Isolated cell colonies arising from a ... CCE is mediated by the oligomerization of stromal interaction molecule (STIM) upon ER Ca2+ store depletion and its subsequent ... Successful transformants, which carried CD4 surface antigen, were enriched by Dynabeads CD4 Positive Isolation Kit (Invitrogen ... Generation of CRISPR-mediated knockout SH-SY5Y cells. CRISPR/Cas9-based genome editing was performed on SH-SY5Y cells to ...
A promising application is the use of antibody profiling to guide development and selection of antigen-specific therapies to ... Major barriers to development of antigen-specific therapies for T-cell-mediated autoimmune diseases, such as multiple sclerosis ... analysis of the antibody repertoires revealed clonal families of heavy-chain sequences and enabled rational selection of ... Antigen arrays for antibody profiling CURRENT OPINION IN CHEMICAL BIOLOGY Robinson, W. H. 2006; 10 (1): 67-72 Abstract. Antigen ...
Clonal selection theory. Jerne, Talmage and Burnet in the late 1950s found the clonal selection theory. This proved all the ... James Gowans in 1959 showed that lymphocytes had a role in mediating both cell-mediated and humoral responses. ... The biochemical properties of antigen-antibody binding interactions were examined in more detail in the late 1930s by John ... Cell-mediated immunity and humoral immunity. Related Stories. *Antibody target implicated in neuropsychiatric symptoms of lupus ...
Result of clonal selection. Carry out immune response to destroy or deactivates antigen.. Gets shit done. Then dies.. Active ... Cell Mediated. AKA Delayed hypersensitivity. 12-72 hours after exposure, immunocompetent T cells return to site and stimulate ... Result of clonal selection. Do not actively participate in initial immune response. Response quicker in subsequent invasion. ... Self-antigens. AKA human leukocyte antigens (HLA). Help T cells recognize cell as self/foreign ...
... amongst billions based on its antigen specificity is called clonal selection (Figure 3). This process allows the immune system ... Their receptors are used only for the detection of foreign antigens, and do not directly mediate an effector response. So even ... IC system I: Clonal selection. The first system Behe describes in chapter 6 is the process of clonal selection, which is how ... Clonal Selection - Behe lists three components as part of the clonal selection systems "core": the membrane-bound ...
... amongst billions based on its antigen specificity is called clonal selection (Figure 3). This process allows the immune system ... Their receptors are used only for the detection of foreign antigens, and do not directly mediate an effector response. So even ... Clonal Selection - Behe lists three components as part of the clonal selection systems "core": the membrane-bound ... Behe has this to say about the evolution of the clonal selection system:. "A cell hopefully trying to evolve such a system in ...
  • It is the CD8+ T-cells that will mature and go on to become cytotoxic T cells following their activation with a class I-restricted antigen. (wikipedia.org)
  • AIRE can maintain central immune tolerance, since AIRE clears auto-reactive T cells and induces Treg production by regulating the expression of peripheral tissue-specific antigens (TSAs) in mTECs . (thefreelibrary.com)