| immunoglobulin allotypes | Hereditary serologic types based on antigenic differences in the light and heavy chains of immunoglobulins due to allelic genes in the gene loci coding the chains. The inv system applies to the kappa light chains, the gm system applies to the heavy chains of IgG. (12 Dec 1998) |
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| 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. (12 Dec 1998) |
| immunoglobulin D | <immunology> This immunoglobulin (184 kD) is present at a low level (3-400 mcg/ml) but is a major immunoglobulin on the surface of B lymphocytes where it may play a role in antigen recognition. Its structure resembles that of immunoglobulin G but the heavy chains are of the delta type. (30 Mar 1998) |
| immunoglobulin domains | Structural units of immunoglobulin heavy or light chains that are composed of approximately 110 amino acids. Light chains of an immunoglobulin are composed of one constant domain and one variable domain. Heavy chains are composed of either three or four constant domains and one variable domain. (05 Mar 2000) |
| immunoglobulin E | <immunology> Class of immunoglobulin (188 kD) associated with immediate type hypersensitivity reactions and helminth infections. Present in very low amounts in serum and mostly bound to mast cells and basophils that have an immunoglobulin E specific Fc receptor (FceR). Immunoglobulin E has a high carbohydrate content and is also present in external secretions. Heavy chain of epsilon type. (30 Mar 1998) |
| immunoglobulin electrophoresis | <immunology, investigation> A test that detects and measures the various immunoglobulins in the blood. In the normal assay no monoclonal antibodies are detected but in multiple myeloma and chronic lymphocytic leukaemia a single clone of lymphocytes can produce one type of immunoglobulin that is detected in the electrophoresis as monoclonal (made by one cell clone). (30 Mar 1998) |
| immunoglobulin G | <immunology> The classical immunoglobulin class also called 7S IgG (150 kD). Composed of two identical light and two identical heavy chains, the constant region sequence of the heavy chains being of the type. The molecule can be described in another way as being composed of two Fab and an Fc fragment. The Fabs include the antigen combining sites, the Fc region consists of the remaining constant sequence domains of the heavy chains and contains cell binding and complement binding sites. Immunoglobulin Gs act on pathogens by agglutinating them, by opsonising them, by activating complement mediated reactions against cellular pathogens and by neutralising toxins. They can pass across the placenta to the foetus as maternal antibodies, unlike other Ig classes. In humans four main subclasses are known, IgG2 differs from the rest in not being transferred across the placenta and IgG4 does not fix complement. Immunoglobulin G is present at 8-16 mg/ml in serum. Synonym: gamma globulin. (30 Mar 1998) |
| immunoglobulin gm allotypes | Hereditary allotypic markers associated with the heavy chain of IgG. (12 Dec 1998) |
| immunoglobulin G subclass deficiency | A rare inherited disorder in which there are reduced levels of one or more IgG subclasses resulting from defective heavy chain genes or an abnormality in the regulation of immunoglobulin isotype switching. (05 Mar 2000) |
| 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 variable regions of both immunoglobin polypeptide chains. (12 Dec 1998) |
| immunoglobulin inv allotypes | Hereditary allotypic markers associated with the light chain of IgG. (12 Dec 1998) |
| 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. (12 Dec 1998) |
| immunoglobulin joining region | Segment of light and heavy chains of mouse and human immunoglobulins where the genes for the variable region upstream join those of the constant region downstream (an important part of the antibody diversity mechanism). In the joining region of the light chain are the genes coding for amino acids 96 to 107. (12 Dec 1998) |
| immunoglobulin M | <immunology> An immunoglobulin M molecule (970 kD) is built up from five immunoglobulin G type monomers joined together, with the assistance of J chains, to form a cyclic pentamer. Immunoglobulin M binds complement and a single molecule bound to a cell surface can lyse that cell. Immunoglobulin M is usually produced first in an immune response before immunoglobulin G. The human red cell isoantibodies are immunoglobulin M antibodies. Heavy chain (mu chain) is rather larger than the heavy chains of other immunoglobulins. (30 Mar 1998) |
| immunoglobulin superfamily | <immunology> A large group of proteins with immunoglobulin like domains. most are involved with cell surface recognition events. Sequence homologyy suggests that immunoglobulins, MHC molecules, some cell adhesion molecules and cytokines receptors share close homology and thus belong to a multigene family. (30 Mar 1998) |