| EMA | electronic microanalyzer; emergency medical assistance, emergency medical assistant; endothelial mon... |
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| GSA | general somatic afferent; group-specific antigen; Gross virus antigen; guanidinosuccinic acid |
| HA | H antigen; Hakim-Adams [syndrome]; halothane anesthesia; Hartley [guinea pig]; headache; health alli... |
| HAA | hearing aid amplifier; hemolytic anemia antigen; hepatitis-associated antigen; hospital activity ana... |
| HTA | heterophil transplantation antigen; human thymocyte antigen; hydroxytryptamine; hypophysiotropic are... |
| blood group antigen | <haematology, immunology> The set of cell surface antigens found chiefly, but not solely, on blood cells. More than fifteen different blood group systems are recognised in humans. There may be naturally occurring antibodies without immunisation, especially in the case of the ABO system and matching blood groups is important for safe transfusion. In most cases the antigenic determinant resides in the carbohydrate chains of membrane glycoproteins or glycolipids. See: Rhesus, Duffy, Kell, Lewis and MN. (25 Jun 1999) |
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| cancer antigen 125 test | Test for cell-surface antigen found on derivatives of coelomic epithelium. Elevated levels of this antigen are associated with ovarian malignancy and benign pelvic disease such as endometriosis. (05 Mar 2000) |
| capsular antigen | That found only in the capsules of certain microorganisms; e.g., the specific polysaccharides of various types of pneumococci. (05 Mar 2000) |
| carcinoembryonic antigen | <tumour marker> Antigen found in blood of patients suffering from cancer of colon and some other diseases, that is otherwise normally found in foetal gut tissue. (19 Jan 1998) |
| macrophage-1 antigen | An adhesion-promoting leukocyte surface membrane heterodimer. The alpha subunit consists of the CD11b antigen and the beta subunit of the CD18 antigen (antigens, CD18). The antigen, which is an integrin, functions both as a receptor for complement 3 and in cell-cell and cell-substrate adhesive interactions. (12 Dec 1998) |
| V antigen | Viral antigen that is intimately associated with the virus particle, is protein in nature, has multiple antigenicities, and is strain-specific; antibody to such antigen is demonstrable as protective or neutralizing antibody. (05 Mar 2000) |
| variable antigen | <immunology> Term usually applied to the surface antigens of those parasitic or pathogenic organisms that can alter their antigenic character to evade host immune responses. (See antigenic variation). (18 Nov 1997) |
| G antigen | An antigenic glycoprotein frequently associated with viral surfaces. Origin: Ger. Gebundenes, bound (05 Mar 2000) |
| major histocompatibility antigen | <immunology> A set of plasmalemmal glycoprotein antigens involved in rapid (e.g. 7 days in the mouse) graft rejection and other immune phenomena. The minor histocompatibility antigens are involved in much slower rejection phenomena. The major antigens show remarkable polymorphism and occur as Class I and Class II types in mammals, birds may have a Class III molecule as well. See: histocompatibility antigens, MHC restriction. (18 Nov 1997) |
| P antigen | <haematology, immunology> Antigenic determinant on the surface of human red blood cells to which the Donath Landsteiner antibody reacts. This antibody binds in the cold (a cold IgG), but elutes from red cells at 37쵣, is particularly associated with tertiary syphylis and its binding causes paroxysmal nocturnal haemoglobinuria. (18 Nov 1997) |
| R antigen | Those that produce active haemolysins (O and S) which cause a zone of clear haemolysis on the blood agar medium in the area of the colony; beta-haemolytic streptococci are divided into groups (A to O) on the basis of cell wall C carbohydrate (see Lancefield classification); Group A (in the strains pathogenic for man) comprises more than 50 types (designated by Arabic numerals) determined by cell wall M protein, which seems to be associated closely with virulence and is produced chiefly by strains with matt or mucoid colonies, in contrast to nonvirulent, glossy colony-producing strains; other surface protein antigens such as R and T (T substance), and the nucleoprotein fraction (P substance) seem to be of less importance. The more than 20 extracellular substances elaborated by strains of beta-haemolytic streptococci include erythrogenic toxin (elaborated only by lysogenic strains), deoxyribonuclease (streptodornase), haemolysins (streptolysins O and S), hyaluronidase, and streptokinase. Synonym: haemolytic streptococci. (05 Mar 2000) |
| gene rearrangement, alpha-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the alpha-chain of antigen receptors. (12 Dec 1998) |
| gene rearrangement, beta-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the beta-chain of antigen receptors. (12 Dec 1998) |
| gene rearrangement, delta-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the delta-chain of antigen receptors. (12 Dec 1998) |
| gene rearrangement, gamma-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the gamma-chain of antigen receptors. (12 Dec 1998) |