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.Immunoglobulin G: The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.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.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.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.Immunoglobulins, Intravenous: Immunoglobulin preparations used in intravenous infusion, containing primarily IMMUNOGLOBULIN G. They are used to treat a variety of diseases associated with decreased or abnormal immunoglobulin levels including pediatric AIDS; primary HYPERGAMMAGLOBULINEMIA; SCID; CYTOMEGALOVIRUS infections in transplant recipients, LYMPHOCYTIC LEUKEMIA, CHRONIC; Kawasaki syndrome, infection in neonates, and IDIOPATHIC THROMBOCYTOPENIC PURPURA.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).Immunoglobulin Light Chains: Polypeptide chains, consisting of 211 to 217 amino acid residues and having a molecular weight of approximately 22 kDa. There are two major types of light chains, kappa and lambda. Two Ig light chains and two Ig heavy chains (IMMUNOGLOBULIN HEAVY CHAINS) make one immunoglobulin molecule.Immunoglobulin kappa-Chains: One of the types of light chains of the immunoglobulins with a molecular weight of approximately 22 kDa.Immunoglobulin E: An immunoglobulin associated with MAST CELLS. Overexpression has been associated with allergic hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).Immunoglobulin A, Secretory: The principle immunoglobulin in exocrine secretions such as milk, respiratory and intestinal mucin, saliva and tears. The complete molecule (around 400 kD) is composed of two four-chain units of IMMUNOGLOBULIN A, one SECRETORY COMPONENT and one J chain (IMMUNOGLOBULIN J-CHAINS).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.Immunoglobulin mu-Chains: The class of heavy chains found in IMMUNOGLOBULIN M. They have a molecular weight of approximately 72 kDa and they contain about 57 amino acid residues arranged in five domains and have more oligosaccharide branches and a higher carbohydrate content than the heavy chains of IMMUNOGLOBULIN G.Immunoglobulin Isotypes: The classes of immunoglobulins found in any species of animal. In man there are nine classes that migrate in five different groups in electrophoresis; they each consist of two light and two heavy protein chains, and each group has distinguishing structural and functional properties.Immunoglobulin lambda-Chains: One of the types of light chain subunits of the immunoglobulins with a molecular weight of approximately 22 kDa.Immunoglobulin D: An immunoglobulin which accounts for less than 1% of plasma immunoglobulin. It is found on the membrane of many circulating B LYMPHOCYTES.Immunoglobulin Constant Regions: The domains of the immunoglobulin molecules that are invariable in their amino acid sequence within any class or subclass of immunoglobulin. They confer biological as well as structural functions to immunoglobulins. One each on both the light chains and the heavy chains comprises the C-terminus half of the IMMUNOGLOBULIN FAB FRAGMENT and two or three of them make up the rest of the heavy chains (all of the IMMUNOGLOBULIN FC FRAGMENT)Immunoglobulin Fc Fragments: Crystallizable fragments composed of the carboxy-terminal halves of both IMMUNOGLOBULIN HEAVY CHAINS linked to each other by disulfide bonds. Fc fragments contain the carboxy-terminal parts of the heavy chain constant regions that are responsible for the effector functions of an immunoglobulin (COMPLEMENT fixation, binding to the cell membrane via FC RECEPTORS, and placental transport). This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme PAPAIN.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.Immunoglobulin Class Switching: Gene rearrangement of the B-lymphocyte which results in a substitution in the type of heavy-chain constant region that is expressed. This allows the effector response to change while the antigen binding specificity (variable region) remains the same. The majority of class switching occurs by a DNA recombination event but it also can take place at the level of RNA processing.Immunoglobulin gamma-Chains: Heavy chains of IMMUNOGLOBULIN G having a molecular weight of approximately 51 kDa. They contain about 450 amino acid residues arranged in four domains and an oligosaccharide component covalently bound to the Fc fragment constant region. The gamma heavy chain subclasses (for example, gamma 1, gamma 2a, and gamma 2b) of the IMMUNOGLOBULIN G isotype subclasses (IgG1, IgG2A, and IgG2B) resemble each other more closely than the heavy chains of the other IMMUNOGLOBULIN ISOTYPES.Immunoglobulin Fab Fragments: Univalent antigen-binding fragments composed of one entire IMMUNOGLOBULIN LIGHT CHAIN and the amino terminal end of one of the IMMUNOGLOBULIN HEAVY CHAINS from the hinge region, linked to each other by disulfide bonds. Fab contains the IMMUNOGLOBULIN VARIABLE REGIONS, which are part of the antigen-binding site, and the first IMMUNOGLOBULIN CONSTANT REGIONS. This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme PAPAIN.Immunoglobulin J-Chains: A 15 kD "joining" peptide that forms one of the linkages between monomers of IMMUNOGLOBULIN A or IMMUNOGLOBULIN M in the formation of polymeric immunoglobulins. There is one J chain per one IgA dimer or one IgM pentamer. It is also involved in binding the polymeric immunoglobulins to POLYMERIC IMMUNOGLOBULIN RECEPTOR which is necessary for their transcytosis to the lumen. It is distinguished from the IMMUNOGLOBULIN JOINING REGION which is part of the IMMUNOGLOBULIN VARIABLE REGION of the immunoglobulin light and heavy chains.Immunoglobulin Fragments: Partial immunoglobulin molecules resulting from selective cleavage by proteolytic enzymes or generated through PROTEIN ENGINEERING techniques.Immunoglobulin Allotypes: Allelic variants of the immunoglobulin light chains (IMMUNOGLOBULIN LIGHT CHAINS) or heavy chains (IMMUNOGLOBULIN HEAVY CHAINS) encoded by ALLELES of IMMUNOGLOBULIN GENES.Receptors, Polymeric Immunoglobulin: Specialized Fc receptors (RECEPTORS, FC) for polymeric immunoglobulins, which mediate transcytosis of polymeric IMMUNOGLOBULIN A and IMMUNOGLOBULIN M into external secretions. They are found on the surfaces of epithelial cells and hepatocytes. After binding to IMMUNOGLOBULIN A, the receptor-ligand complex undergoes endocytosis, transport by vesicle, and secretion into the lumen by exocytosis. Before release, the part of the receptor (SECRETORY COMPONENT) that is bound to IMMUNOGLOBULIN A is proteolytically cleaved from its transmembrane tail. (From Rosen et al., The Dictionary of Immunology, 1989)Immunoglobulin Joining Region: A segment of the immunoglobulin heavy chains, encoded by the IMMUNOGLOBULIN HEAVY CHAIN GENES in the J segment where, during the maturation of B-LYMPHOCYTES; the gene segment for the variable region upstream is joined to a constant region gene segment downstream. The exact position of joining of the two gene segments is variable and contributes to ANTIBODY DIVERSITY. It is distinguished from the IMMUNOGLOBULIN J CHAINS; a separate polypeptide that serves as a linkage piece in polymeric IGA or IGM.Antibodies, Bacterial: Immunoglobulins produced in a response to BACTERIAL ANTIGENS.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.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.Myeloma Proteins: Abnormal immunoglobulins characteristic of MULTIPLE MYELOMA.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.Genes, Immunoglobulin Heavy Chain: Genes and gene segments encoding the IMMUNOGLOBULIN HEAVY CHAINS. Gene segments of the heavy chain genes are symbolized V (variable), D (diversity), J (joining), and C (constant).Somatic Hypermutation, Immunoglobulin: A programmed mutation process whereby changes are introduced to the nucleotide sequence of immunoglobulin gene DNA during development.Plasmacytoma: Any discrete, presumably solitary, mass of neoplastic PLASMA CELLS either in BONE MARROW or various extramedullary sites.Immunoglobulin delta-Chains: The class of heavy chains found in IMMUNOGLOBULIN D. They have a molecular weight of approximately 64 kDa and they contain about 500 amino acid residues arranged in four domains and an oligosaccharide component covalently bound to the Fc fragment constant region.Immunoglobulin Switch Region: A site located in the INTRONS at the 5' end of each constant region segment of a immunoglobulin heavy-chain gene where recombination (or rearrangement) occur during IMMUNOGLOBULIN CLASS SWITCHING. Ig switch regions are found on genes encoding all five classes (IMMUNOGLOBULIN ISOTYPES) of IMMUNOGLOBULIN HEAVY CHAINS.Immunoglobulin alpha-Chains: The class of heavy chains found in IMMUNOGLOBULIN A. They have a molecular weight of approximately 58 kDa and contain about 470 amino acid residues arranged in four domains and an oligosaccharide component bound covalently to their Fc fragment constant region.Antibodies, Anti-Idiotypic: Antibodies which react with the individual structural determinants (idiotopes) on the variable region of other antibodies.Immunoglobulin Idiotypes: Unique genetically-controlled determinants present on ANTIBODIES whose specificity is limited to a single group of proteins (e.g., another antibody molecule or an individual myeloma protein). The idiotype appears to represent the antigenicity of the antigen-binding site of the antibody and to be genetically codetermined with it. The idiotypic determinants have been precisely located to the IMMUNOGLOBULIN VARIABLE REGION of both immunoglobin polypeptide chains.gamma-Globulins: Serum globulins that migrate to the gamma region (most positively charged) upon ELECTROPHORESIS. At one time, gamma-globulins came to be used as a synonym for immunoglobulins since most immunoglobulins are gamma globulins and conversely most gamma globulins are immunoglobulins. But since some immunoglobulins exhibit an alpha or beta electrophoretic mobility, that usage is in decline.Antibodies, Viral: Immunoglobulins produced in response to VIRAL ANTIGENS.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.Secretory Component: The extracellular moiety of the POLYMERIC IMMUNOGLOBULIN RECEPTOR found alone or complexed with IGA or IGM, in a variety of external secretions (tears, bile, colostrum.) Secretory component is derived by proteolytic cleavage of the receptor during transcytosis. When immunoglobulins IgA and IgM are bound to the receptor, during their transcytosis secretory component becomes covalently attached to them generating SECRETORY IMMUNOGLOBULIN A or secretory IMMUNOGLOBULIN M.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Agammaglobulinemia: An immunologic deficiency state characterized by an extremely low level of generally all classes of gamma-globulin in the blood.Antibody Formation: The production of ANTIBODIES by proliferating and differentiated B-LYMPHOCYTES under stimulation by ANTIGENS.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Immunoglobulin Gm Allotypes: Allelic variants of the gamma-immunoglobulin heavy chain (IMMUNOGLOBULIN GAMMA-CHAINS) encoded by ALLELES of IMMUNOGLOBULIN HEAVY CHAIN GENES.Colostrum: The thin, yellow, serous fluid secreted by the mammary glands during pregnancy and immediately postpartum before lactation begins. It consists of immunologically active substances, white blood cells, water, protein, fat, and carbohydrates.Receptors, Fc: Molecules found on the surface of some, but not all, B-lymphocytes, T-lymphocytes, and macrophages, which recognize and combine with the Fc (crystallizable) portion of immunoglobulin molecules.Immunization, Passive: Transfer of immunity from immunized to non-immune host by administration of serum antibodies, or transplantation of lymphocytes (ADOPTIVE TRANSFER).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.Mice, Inbred BALB CAntigen-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.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.Gene Rearrangement, B-Lymphocyte, Heavy Chain: Ordered rearrangement of B-lymphocyte variable gene regions of the IMMUNOGLOBULIN HEAVY CHAINS, thereby contributing to antibody diversity. It occurs during the first stage of differentiation of the IMMATURE B-LYMPHOCYTES.Gene Rearrangement, B-Lymphocyte: Ordered rearrangement of B-lymphocyte variable gene regions coding for the IMMUNOGLOBULIN CHAINS, thereby contributing to antibody diversity. It occurs during the differentiation of the IMMATURE B-LYMPHOCYTES.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.Staphylococcal Protein A: A protein present in the cell wall of most Staphylococcus aureus strains. The protein selectively binds to the Fc region of human normal and myeloma-derived IMMUNOGLOBULIN G. It elicits antibody activity and may cause hypersensitivity reactions due to histamine release; has also been used as cell surface antigen marker and in the clinical assessment of B lymphocyte function.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.Spleen: An encapsulated lymphatic organ through which venous blood filters.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.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.Plasma Cells: Specialized forms of antibody-producing B-LYMPHOCYTES. They synthesize and secrete immunoglobulin. They are found only in lymphoid organs and at sites of immune responses and normally do not circulate in the blood or lymph. (Rosen et al., Dictionary of Immunology, 1989, p169 & Abbas et al., Cellular and Molecular Immunology, 2d ed, p20)Autoantibodies: Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.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.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.Genes, Immunoglobulin Light Chain: Genes and gene segments encoding the IMMUNOGLOBULIN LIGHT CHAINS. Gene segments of the light chain genes are designated as V (variable), J (joining), and C (constant).Immunoglobulin epsilon-Chains: The class of heavy chains found in IMMUNOGLOBULIN E. They have a molecular weight of approximately 72 kDa and they contain about 550 amino acid residues arranged in five domains and about three times more carbohydrate than the heavy chains of IMMUNOGLOBULIN A; IMMUNOGLOBULIN D; and IMMUNOGLOBULIN G.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).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.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.Gene Rearrangement: The ordered rearrangement of gene regions by DNA recombination such as that which occurs normally during development.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.Gene Rearrangement, B-Lymphocyte, Light Chain: Ordered rearrangement of B-lymphocyte variable gene regions coding for the kappa or lambda IMMUNOGLOBULIN LIGHT CHAINS, thereby contributing to antibody diversity. It occurs during the second stage of differentiation of the IMMATURE B-LYMPHOCYTES.Immunologic Deficiency Syndromes: Syndromes in which there is a deficiency or defect in the mechanisms of immunity, either cellular or humoral.Antigens, Bacterial: Substances elaborated by bacteria that have antigenic activity.IgA Deficiency: A dysgammaglobulinemia characterized by a deficiency of IMMUNOGLOBULIN A.Cross Reactions: Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.Pokeweed Mitogens: Proteins isolated from the roots of the pokeweed, Phytolacca americana, that agglutinate some erythrocytes, stimulate mitosis and antibody synthesis in lymphocytes, and induce activation of plasma cells.Complement System Proteins: Serum glycoproteins participating in the host defense mechanism of COMPLEMENT ACTIVATION that creates the COMPLEMENT MEMBRANE ATTACK COMPLEX. Included are glycoproteins in the various pathways of complement activation (CLASSICAL COMPLEMENT PATHWAY; ALTERNATIVE COMPLEMENT PATHWAY; and LECTIN COMPLEMENT PATHWAY).Epitopes: Sites on an antigen that interact with specific antibodies.Antibodies, Protozoan: Immunoglobulins produced in a response to PROTOZOAN ANTIGENS.Receptors, IgG: Specific molecular sites on the surface of various cells, including B-lymphocytes and macrophages, that combine with IMMUNOGLOBULIN Gs. Three subclasses exist: Fc gamma RI (the CD64 antigen, a low affinity receptor), Fc gamma RII (the CD32 antigen, a high affinity receptor), and Fc gamma RIII (the CD16 antigen, a low affinity receptor).Immunoglobulins, Thyroid-Stimulating: Autoantibodies that bind to the thyroid-stimulating hormone (TSH) receptor (RECEPTORS, THYROTROPIN) on thyroid epithelial cells. The autoantibodies mimic TSH causing an unregulated production of thyroid hormones characteristic of GRAVES DISEASE.Antigen-Antibody Reactions: The processes triggered by interactions of ANTIBODIES with their ANTIGENS.Hypergammaglobulinemia: An excess of GAMMA-GLOBULINS in the serum due to chronic infections or PARAPROTEINEMIAS.Dysgammaglobulinemia: An immunologic deficiency state characterized by selective deficiencies of one or more, but not all, classes of immunoglobulins.Antibody Diversity: The phenomenon of immense variability characteristic of ANTIBODIES. It enables the IMMUNE SYSTEM to react specifically against the essentially unlimited kinds of ANTIGENS it encounters. Antibody diversity is accounted for by three main theories: (1) the Germ Line Theory, which holds that each antibody-producing cell has genes coding for all possible antibody specificities, but expresses only the one stimulated by antigen; (2) the Somatic Mutation Theory, which holds that antibody-producing cells contain only a few genes, which produce antibody diversity by mutation; and (3) the Gene Rearrangement Theory, which holds that antibody diversity is generated by the rearrangement of IMMUNOGLOBULIN VARIABLE REGION gene segments during the differentiation of the ANTIBODY-PRODUCING CELLS.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.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.Immunoglobulin Km Allotypes: Allelic variants of the kappa light chains (IMMUNOGLOBULIN KAPPA-CHAINS) encoded by ALLELES of IMMUNOGLOBULIN LIGHT CHAIN GENES.Antibody-Producing Cells: Cells of the lymphoid series that can react with antigen to produce specific cell products called antibodies. Various cell subpopulations, often B-lymphocytes, can be defined, based on the different classes of immunoglobulins that they synthesize.Bence Jones Protein: An abnormal protein with unusual thermosolubility characteristics that is found in the urine of patients with MULTIPLE MYELOMA.Paraproteinemias: A group of related diseases characterized by an unbalanced or disproportionate proliferation of immunoglobulin-producing cells, usually from a single clone. These cells frequently secrete a structurally homogeneous immunoglobulin (M-component) and/or an abnormal immunoglobulin.Complement C3: A glycoprotein that is central in both the classical and the alternative pathway of COMPLEMENT ACTIVATION. C3 can be cleaved into COMPLEMENT C3A and COMPLEMENT C3B, spontaneously at low level or by C3 CONVERTASE at high level. The smaller fragment C3a is an ANAPHYLATOXIN and mediator of local inflammatory process. The larger fragment C3b binds with C3 convertase to form C5 convertase.Saliva: The clear, viscous fluid secreted by the SALIVARY GLANDS and mucous glands of the mouth. It contains MUCINS, water, organic salts, and ptylin.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.Multiple Myeloma: A malignancy of mature PLASMA CELLS engaging in monoclonal immunoglobulin production. It is characterized by hyperglobulinemia, excess Bence-Jones proteins (free monoclonal IMMUNOGLOBULIN LIGHT CHAINS) in the urine, skeletal destruction, bone pain, and fractures. Other features include ANEMIA; HYPERCALCEMIA; and RENAL INSUFFICIENCY.Rheumatoid Factor: Antibodies found in adult RHEUMATOID ARTHRITIS patients that are directed against GAMMA-CHAIN IMMUNOGLOBULINS.Antigens: Substances that are recognized by the immune system and induce an immune reaction.Serologic Tests: Diagnostic procedures involving immunoglobulin reactions.Paraproteins: Abnormal immunoglobulins synthesized by atypical cells of the MONONUCLEAR PHAGOCYTE SYSTEM. Paraproteins containing only light chains lead to Bence Jones paraproteinemia, while the presence of only atypical heavy chains leads to heavy chain disease. Most of the paraproteins show themselves as an M-component (monoclonal gammopathy) in electrophoresis. Diclonal and polyclonal paraproteins are much less frequently encountered.Lymphoma: A general term for various neoplastic diseases of the lymphoid tissue.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.Leukemia, Lymphoid: Leukemia associated with HYPERPLASIA of the lymphoid tissues and increased numbers of circulating malignant LYMPHOCYTES and lymphoblasts.Waldenstrom Macroglobulinemia: A lymphoproliferative disorder characterized by pleomorphic B-LYMPHOCYTES including PLASMA CELLS, with increased levels of monoclonal serum IMMUNOGLOBULIN M. There is lymphoplasmacytic cells infiltration into bone marrow and often other tissues, also known as lymphoplasmacytic lymphoma. Clinical features include ANEMIA; HEMORRHAGES; and hyperviscosity.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).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.Receptors, IgE: Specific molecular sites on the surface of B- and T-lymphocytes which combine with IgEs. Two subclasses exist: low affinity receptors (Fc epsilon RII) and high affinity receptors (Fc epsilon RI).Bacterial Vaccines: Suspensions of attenuated or killed bacteria administered for the prevention or treatment of infectious bacterial disease.IgG Deficiency: A dysgammaglobulinemia characterized by a deficiency of IMMUNOGLOBULIN G.Common Variable Immunodeficiency: Heterogeneous group of immunodeficiency syndromes characterized by hypogammaglobulinemia of most isotypes, variable B-cell defects, and the presence of recurrent bacterial infections.Opsonin Proteins: Proteins that bind to particles and cells to increase susceptibility to PHAGOCYTOSIS, especially ANTIBODIES bound to EPITOPES that attach to FC RECEPTORS. COMPLEMENT C3B may also participate.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.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.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.Genes: A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.Rubella virus: The type (and only) species of RUBIVIRUS causing acute infection in humans, primarily children and young adults. Humans are the only natural host. A live, attenuated vaccine is available for prophylaxis.Cytidine Deaminase: An enzyme that catalyzes the deamination of cytidine, forming uridine. EC 3.5.4.5.Lymphoma, B-Cell: A group of heterogeneous lymphoid tumors generally expressing one or more B-cell antigens or representing malignant transformations of B-lymphocytes.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.Antibodies, Fungal: Immunoglobulins produced in a response to FUNGAL ANTIGENS.Neutralization Tests: The measurement of infection-blocking titer of ANTISERA by testing a series of dilutions for a given virus-antiserum interaction end-point, which is generally the dilution at which tissue cultures inoculated with the serum-virus mixtures demonstrate cytopathology (CPE) or the dilution at which 50% of test animals injected with serum-virus mixtures show infectivity (ID50) or die (LD50).Mice, Inbred C57BLPolymerase 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.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Glomerulonephritis, IGA: A chronic form of glomerulonephritis characterized by deposits of predominantly IMMUNOGLOBULIN A in the mesangial area (GLOMERULAR MESANGIUM). Deposits of COMPLEMENT C3 and IMMUNOGLOBULIN G are also often found. Clinical features may progress from asymptomatic HEMATURIA to END-STAGE KIDNEY DISEASE.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)Immunity, Mucosal: Nonsusceptibility to the pathogenic effects of foreign microorganisms or antigenic substances as a result of antibody secretions of the mucous membranes. Mucosal epithelia in the gastrointestinal, respiratory, and reproductive tracts produce a form of IgA (IMMUNOGLOBULIN A, SECRETORY) that serves to protect these ports of entry into the body.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.Immunity, Maternally-Acquired: Resistance to a disease-causing agent induced by the introduction of maternal immunity into the fetus by transplacental transfer or into the neonate through colostrum and milk.Rho(D) Immune Globulin: Immunizing agent containing IMMUNOGLOBULIN G anti-Rho(D) used for preventing Rh immunization in Rh-negative individuals exposed to Rh-positive red blood cells.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.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)Hemagglutination Tests: Sensitive tests to measure certain antigens, antibodies, or viruses, using their ability to agglutinate certain erythrocytes. (From Stedman, 26th ed)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.Enhancer Elements, Genetic: Cis-acting DNA sequences which can increase transcription of genes. Enhancers can usually function in either orientation and at various distances from a promoter.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.Toxoplasmosis: The acquired form of infection by Toxoplasma gondii in animals and man.Amyloidosis: A group of sporadic, familial and/or inherited, degenerative, and infectious disease processes, linked by the common theme of abnormal protein folding and deposition of AMYLOID. As the amyloid deposits enlarge they displace normal tissue structures, causing disruption of function. Various signs and symptoms depend on the location and size of the deposits.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.Bursa of Fabricius: An epithelial outgrowth of the cloaca in birds similar to the thymus in mammals. It atrophies within 6 months after birth and remains as a fibrous remnant in adult birds. It is composed of lymphoid tissue and prior to involution, is the site of B-lymphocyte maturation.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Interleukin-4: A soluble factor produced by activated T-LYMPHOCYTES that induces the expression of MHC CLASS II GENES and FC RECEPTORS on B-LYMPHOCYTES and causes their proliferation and differentiation. It also acts on T-lymphocytes, MAST CELLS, and several other hematopoietic lineage cells.Molecular Weight: The sum of the weight of all the atoms in a molecule.Immunologic Factors: Biologically active substances whose activities affect or play a role in the functioning of the immune system.Polysaccharides, Bacterial: Polysaccharides found in bacteria and in capsules thereof.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Rosette Formation: The in vitro formation of clusters consisting of a cell (usually a lymphocyte) surrounded by antigenic cells or antigen-bearing particles (usually erythrocytes, which may or may not be coated with antibody or antibody and complement). The rosette-forming cell may be an antibody-forming cell, a memory cell, a T-cell, a cell bearing surface cytophilic antibodies, or a monocyte possessing Fc receptors. Rosette formation can be used to identify specific populations of these cells.Translocation, Genetic: A type of chromosome aberration characterized by CHROMOSOME BREAKAGE and transfer of the broken-off portion to another location, often to a different chromosome.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.Allergens: Antigen-type substances that produce immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).Leukemia, Lymphocytic, Chronic, B-Cell: A chronic leukemia characterized by abnormal B-lymphocytes and often generalized lymphadenopathy. In patients presenting predominately with blood and bone marrow involvement it is called chronic lymphocytic leukemia (CLL); in those predominately with enlarged lymph nodes it is called small lymphocytic lymphoma. These terms represent spectrums of the same disease.Macroglobulins: Serum globulins with high molecular weight. (Dorland, 28th ed)Iodine Isotopes: Stable iodine atoms that have the same atomic number as the element iodine, but differ in atomic weight. I-127 is the only naturally occurring stable iodine isotope.Agglutinins: Substances, usually of biological origin, that cause cells or other organic particles to aggregate and stick to each other. They include those ANTIBODIES which cause aggregation or agglutination of particulate or insoluble ANTIGENS.Phagocytosis: The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (PHAGOCYTES).Burkitt Lymphoma: A form of undifferentiated malignant LYMPHOMA usually found in central Africa, but also reported in other parts of the world. It is commonly manifested as a large osteolytic lesion in the jaw or as an abdominal mass. B-cell antigens are expressed on the immature cells that make up the tumor in virtually all cases of Burkitt lymphoma. The Epstein-Barr virus (HERPESVIRUS 4, HUMAN) has been isolated from Burkitt lymphoma cases in Africa and it is implicated as the causative agent in these cases; however, most non-African cases are EBV-negative.Goats: Any of numerous agile, hollow-horned RUMINANTS of the genus Capra, in the family Bovidae, closely related to the SHEEP.Complementarity Determining Regions: Three regions (CDR1; CDR2 and CDR3) of amino acid sequence in the IMMUNOGLOBULIN VARIABLE REGION that are highly divergent. Together the CDRs from the light and heavy immunoglobulin chains form a surface that is complementary to the antigen. These regions are also present in other members of the immunoglobulin superfamily, for example, T-cell receptors (RECEPTORS, ANTIGEN, T-CELL).Lymph Nodes: They are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system.Hemagglutination Inhibition Tests: Serologic tests in which a known quantity of antigen is added to the serum prior to the addition of a red cell suspension. Reaction result is expressed as the smallest amount of antigen which causes complete inhibition of hemagglutination.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.Chromosomes, Human, Pair 14: A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.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.Sharks: A group of elongate elasmobranchs. Sharks are mostly marine fish, with certain species large and voracious.Autoimmune Diseases: Disorders that are characterized by the production of antibodies that react with host tissues or immune effector cells that are autoreactive to endogenous peptides.Blood Protein Electrophoresis: Electrophoresis applied to BLOOD PROTEINS.Receptors, Immunologic: Cell surface molecules on cells of the immune system that specifically bind surface molecules or messenger molecules and trigger changes in the behavior of cells. Although these receptors were first identified in the immune system, many have important functions elsewhere.Toxoplasma: A genus of protozoa parasitic to birds and mammals. T. gondii is one of the most common infectious pathogenic animal parasites of man.Antibodies, Antinuclear: Autoantibodies directed against various nuclear antigens including DNA, RNA, histones, acidic nuclear proteins, or complexes of these molecular elements. Antinuclear antibodies are found in systemic autoimmune diseases including systemic lupus erythematosus, Sjogren's syndrome, scleroderma, polymyositis, and mixed connective tissue disease.Peyer's Patches: Lymphoid tissue on the mucosa of the small intestine.Immunosorbent Techniques: Techniques for removal by adsorption and subsequent elution of a specific antibody or antigen using an immunosorbent containing the homologous antigen or antibody.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.Skin Tests: Epicutaneous or intradermal application of a sensitizer for demonstration of either delayed or immediate hypersensitivity. Used in diagnosis of hypersensitivity or as a test for cellular immunity.Cryoglobulins: Abnormal immunoglobulins, especially IGG or IGM, that precipitate spontaneously when SERUM is cooled below 37 degrees Celsius. It is characteristic of CRYOGLOBULINEMIA.Evaluation Studies as Topic: Studies determining the effectiveness or value of processes, personnel, and equipment, or the material on conducting such studies. For drugs and devices, CLINICAL TRIALS AS TOPIC; DRUG EVALUATION; and DRUG EVALUATION, PRECLINICAL are available.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.Antigens, Viral: Substances elaborated by viruses that have antigenic activity.V(D)J Recombination: The process by which the V (variable), D (diversity), and J (joining) segments of IMMUNOGLOBULIN GENES or T-CELL RECEPTOR GENES are assembled during the development of LYMPHOID CELLS using NONHOMOLOGOUS DNA END-JOINING.Nephelometry and Turbidimetry: Chemical analysis based on the phenomenon whereby light, passing through a medium with dispersed particles of a different refractive index from that of the medium, is attenuated in intensity by scattering. In turbidimetry, the intensity of light transmitted through the medium, the unscattered light, is measured. In nephelometry, the intensity of the scattered light is measured, usually, but not necessarily, at right angles to the incident light beam.Immunologic Techniques: Techniques used to demonstrate or measure an immune response, and to identify or measure antigens using antibodies.Rubella: An acute infectious disease caused by the RUBELLA VIRUS. The virus enters the respiratory tract via airborne droplet and spreads to the LYMPHATIC SYSTEM.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Lipopolysaccharides: Lipid-containing polysaccharides which are endotoxins and important group-specific antigens. They are often derived from the cell wall of gram-negative bacteria and induce immunoglobulin secretion. The lipopolysaccharide molecule consists of three parts: LIPID A, core polysaccharide, and O-specific chains (O ANTIGENS). When derived from Escherichia coli, lipopolysaccharides serve as polyclonal B-cell mitogens commonly used in laboratory immunology. (From Dorland, 28th ed)Tetanus ToxoidCattle: 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.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Antigens, Protozoan: Any part or derivative of any protozoan that elicits immunity; malaria (Plasmodium) and trypanosome antigens are presently the most frequently encountered.Hypersensitivity: Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.Chromatography, Gel: Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.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.Vaccination: Administration of vaccines to stimulate the host's immune response. This includes any preparation intended for active immunological prophylaxis.Chickens: Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.Blood Proteins: Proteins that are present in blood serum, including SERUM ALBUMIN; BLOOD COAGULATION FACTORS; and many other types of proteins.Transcription, Genetic: The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.Immunologic Capping: An energy dependent process following the crosslinking of B CELL ANTIGEN RECEPTORS by multivalent ligands (bivalent anti-antibodies, LECTINS or ANTIGENS), on the B-cell surface. The crosslinked ligand-antigen receptor complexes collect in patches which flow to and aggregate at one pole of the cell to form a large mass - the cap. The caps may then be endocytosed or shed into the environment.Lymphocyte Cooperation: T-cell enhancement of the B-cell response to thymic-dependent antigens.