| CAPA | cancer-associated polypeptide antigen |
|---|---|
| EBNA | Epstein-Barr virus-associated nuclear antigen |
| EHAA | epidemic hepatitis-associated antigen |
| Ia | immune response gene-associated antigen |
| LAA | left atrial appendage; left atrial area; leukemia-associated antigen; leukocyte ascorbic acid |
| antigen-combining site | See: paratope. (05 Mar 2000) |
|---|---|
| antigen excess | In a precipitation test, the presence of uncombined antigen above that required to combine with all of the antibody; precipitation may be inhibited because the presence of excess antigen gives rise to soluble antigen-antibody complexes, in vivo the resultant antigen-antibody interaction in such an antigen excess may give rise to immune complexes, which have a potential to induce cellular damage; such injury underlies the pathologic changes seen in certain immune complex diseases. (05 Mar 2000) |
| antigen interferon | <cytokine> Interferon elaborated by T lymphocytes in response to either specific antigen or mitogenic stimulation. This type II interferon can be produced by recombinant DNA technology and is similar to the interferon secreted by lymphocytes and has antiviral and antineoplastic activity. Synonym: antigen interferon, immune interferon. Pharmacological action: antineoplastic agent, antiviral agents. (20 Sep 2002) |
| antigen p150,95 | A major adhesion-associated heterodimer molecule expressed by human monocytes, granulocytes, nk cells, and some lymphocytes. The alpha subunit is the CD11c antigen (also called leu-m5), a surface antigen expressed on some myeloid cells. The beta subunit is the CD18 antigen (antigens, CD18). The p150,95 antigen has been shown to play an important role in cell-cell and cell-substrate adhesive interactions. (12 Dec 1998) |
| antigen presentation | A cell that carries on its surface antigen bound to MCH Class I or Class II molecules and presents the antigen in this context to T-cells. Includes macrophages, endothelium, dendritic cells and Langerhans cells of the skin. See: MHC restriction, histocompatibility antigens. (18 Nov 1997) |
| antigen-presenting cells | Immunocompetent cells, usually ia positive, that mediate the cellular immune response by processing and presenting antigens or mitogens which stimulate T-cell activation. (12 Dec 1998) |
| antigen processing | Modification of an antigen by accessory cells. This usually involves endocytosis of the antigen and either minimal cleavage or unfolding. The processed antigen is then presented in modified form by the accessory cell. (18 Nov 1997) |
| antigen shift | Abrupt change in antigens expressed by a species or variety of organisms. Usually seen in microorganisms where the change may allow escape from immune recognition. Antigenic drift is a more gradual change. See: antigenic variation. (18 Nov 1997) |
| antigen unit | The smallest amount of antigen that, in the presence of specific antiserum, will fix 1 complement unit. (05 Mar 2000) |
| aspergillus antigen skin test | <investigation> An antigen, prepared from aspergillus, is injected into the skin. In 48 to 72 hours the site is read as positive or negative. A positive skin test (inflammation at the test site) indicates prior exposure to aspergillus and therefore a risk for developing aspergillosis. (27 Sep 1997) |
| Au antigen | Auberger blood group |
| Aus antigen | <virology> An envelope antigen now known as HBsAg of Hepatitis B virus. Appearance of the antigen in serum is associated with a phase of high infectivity. (18 Nov 1997) |
| Australia antigen | <virology> An envelope antigen now known as HBsAg of Hepatitis B virus. Appearance of the antigen in serum is associated with a phase of high infectivity. (18 Nov 1997) |
| becker antigen | bea antigen |
| 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) |