| differentiation antigen | Any large structural macromolecule that can be detected by immune reagents and that also is associated with the differentiation of a particular cell type or types. Many cells can be identified by their possession of a unique set of differentiation antigens. There should be no implication that the antigens cause differentiation. (18 Nov 1997) |
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| Ia antigen | Antigens coded for by the I region of the MHC complex. The majority, if not all, such antigens are Class II molecules composed of _ and _ polypeptide chains. (18 Nov 1997) |
| incomplete antigen | <immunology, molecular biology> Could be considered an isolated epitope: although a hapten (by definition) has an antibody directed against it, the hapten alone will not induce an immune response if injected into an animal, it must be conjugated to a carrier (usually a protein). The hapten constitutes a single antigenic determinant, perhaps the best known example is dinitro phenol (DNP) that can be conjugated to BSA and against which antiDNP antibodies are produced (antibodies to the BSA can be adsorbed out). Because the hapten is monovalent, immune complex formation will be blocked if the soluble hapten is present as well as the hapten carrier conjugate (assuming there is more than one hapten per carrier then an immune precipitate can be formed). Competitive inhibition by the soluble small molecule is sometimes referred to as haptenic inhibition and this term has carried over into lectin mediated haemagglutination where monosaccharides are added to try to block haemagglutination: the blocking sugar defines the specificity of the lectin. (18 Nov 1997) |
| InV group antigen | Allotypic antigens that are present on human kappa immunoglobulin light chains. Synonym: InV group antigen. (05 Mar 2000) |
| Ir associated antigen | Antigens coded for by IR (immune response) genes or antigens coded for by the genome close to the IR genes. See: Ia antigens. (18 Nov 1997) |
| islet cell antigen-related protein-tyrosine phosphatase | <enzyme> Receptor-like autoantigen found in insulin-dependent diabetes; genbank l76258 Registry number: EC 3.1.3.- Synonym: iar ptp (26 Jun 1999) |
| O antigen | Somatic antigen of enteric gram-negative bacteria. External part of cell wall lipopolysaccharide. See: H antigen. See ABO blood group, Blood Groups appendix. (05 Mar 2000) |
| O-antigen depolymerase | <enzyme> Cleaves surface o-polysaccharide (o-antigen)of salmonella anatum Registry number: EC 3.2.1.- (26 Jun 1999) |
| O-antigen polymerase | <enzyme> Involved in the binding of o-antigen repeat units and in polymerizing into the o-antigen chain; mw 43.7 kD; genbank x71970 Registry number: EC 2.4.1.- Synonym: rfc protein, s. Flexneri, rfc gene product, o-antigen polymerase, shigella, o-antigen polymerase, pseudomonas, rfc protein, pseudomonas, o-antigen polymerase, e. Coli (26 Jun 1999) |
| organ-specific antigen | A heterogenetic antigen with organ specificity; e.g., in addition to species-specific antigen, kidney of one species contains antigen that is identical to that in kidney of other species. Synonym: tissue-specific antigen. (05 Mar 2000) |
| Tac antigen | An antigenic determinant of the human interleukin 2 receptor that is identified by a murine monoclonal antibody, anti-Tac. Binding of this antigen prevents the proliferation of T-cells, which is normally stimulated by binding interleukin-2. (05 Mar 2000) |
| T antigen | <molecular biology> Proteins coded by viral genes that are expressed early in the replication cycle of papovaviruses such as SV40 and polyoma. Essential for normal viral replication, they are also expressed in nonpermissive cells transformed by these viruses. Originally detected as Tumour antigens by immunofluorescence with antisera from tumour bearing animals. SV40 has two, large T and small t, polyoma has three, large, middle and small. Appear to be collectively responsible for transformation by these viruses. (14 Oct 1997) |
| T-cell antigen receptors | Receptors present on T-cells that interact with both processed antigen and major histocompatibility antigens simultaneously. (05 Mar 2000) |
| T-dependent antigen | An antigen that requires T helper cells in addition to appropriate B-cells. Most antigens are T-dependent. (05 Mar 2000) |
| theta antigen | A surface glycoprotein that is present on thymocytes of mice and rats. (05 Mar 2000) |