| human leukocyte antigen | <immunology> A genetic fingerprint on white blood cells and platelets, composed of proteins that play a critical role in activating the bodys immune system to respond to foreign organisms. Acronym: HLA (16 Dec 1997) |
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| human leukocyte-associated antigens | Proteins on the outer part of body cells that help fight illness. These proteins vary from person to person. Scientists think that people with certain types of HLA antigens are more likely to develop insulin-dependent diabetes.The HLA antigens are also responsible for histocompatibility reactions. (09 Oct 1997) |
| leukocyte common antigen | Family of glycoproteins found on most leukocytes and absent from other cell types. These cell surface antigens can comprise up to 10% of the membrane proteins. (05 Mar 2000) |
| antigen-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. If the antigen is polyvalent the complex may be insoluble. Immune complexes activate complement through the classical pathway. See: glomerulonephritis, Arthus reaction, type III hypersensitivity. (12 Dec 1998) |
| receptor-CD3 complex, antigen, T-cell | Molecule composed of the non-covalent association of the T-cell antigen receptor (receptors, antigen, T-cell) with the CD3 complex (antigens, CD3). This association is required for the surface expression and function of both components. The molecule consists of up to seven chains: either the alpha/beta or gamma/delta chains of the T-cell receptor, and four or five chains in the CD3 complex. (12 Dec 1998) |
| human lymphocyte antigen | A system designation for the gene products of at least four linked loci (A, B, C, and D) and a member of subloci on the sixth human chromosome which have been shown to have a strong influence on human allotransplantation, transfusions in refractory patients, and certain disease associations; more than 50 alleles are recognised, most of which are at loci HLA-A and HLA-B; autosomal dominant inheritance. (05 Mar 2000) |
| acidophilic leukocyte | A polymorphonuclear leukocyte characterised by many large or prominent, refractile, cytoplasmic granules that are fairly uniform in size and bright yellow-red or orange when treated with Wright's or similar stains; the nuclei are usually larger than those of neutrophils, do not stain as deeply, and characteristically have two lobes (a third lobe is sometimes interposed on the connecting strand of chromatin); these leukocyte's are motile phagocytes with distinctive antiparasitic functions. Synonym: acidophilic leukocyte, eosinocyte, eosinophil, eosinophile, oxyphil, oxyphile, oxyphilic leukocyte. (05 Mar 2000) |
| agranular leukocyte | <haematology> A general, non-specific term frequently used with reference to lymphocytes, monocytes, and plasma cells; although the cytoplasm of a lymphocyte or monocyte contains tiny granules, it is nongranular in comparison with that of a neutrophil, basophil, or eosinophil. See: leukocyte. Synonym: agranular leukocyte. (05 Mar 2000) |
| automated differential leukocyte counter | An instrument using digital imaging or cytochemical techniques to differentiate leukocytes. (05 Mar 2000) |
| basophilic leukocyte | A polymorphonuclear leukocyte characterised by many large, coarse, metachromatic granules (dark purple or blue-black when treated with Wright's or similar stains) that usually fill the cytoplasm and may almost mask the nucleus; these leukocyte's are unique in that they usually do not occur in increased numbers as the result of acute infectious disease, and their phagocytic qualities are probably not significant; the granules, which contain heparin and histamine, may degranulate in response to hypersensitivity reactions and can be of significance in general inflammation. Synonym: basocyte, basophilocyte, mast leukocyte. (05 Mar 2000) |
| receptors, leukocyte-adhesion | Family of proteins associated with the capacity of leukocytes, including lymphocytes, monocytes, and neutrophils, to adhere to each other and to certain substrata, e.g., the c3bi component of complement. Members of this family are the lymphocyte function-associated antigen-1 (lfa-1), the macrophage-1 antigen (mac-1), and the antigen p150,95 or p150,95 leukocyte adhesion protein. They all share a common beta-subunit which is the CD18 antigen. All three of the above antigens are absent in inherited leukocyte-adhesion deficiency syndrome, which is characterised by recurrent bacterial infections, impaired pus formation, and wound healing as well as abnormalities in a wide spectrum of adherence-dependent functions of granulocytes, monocytes, and lymphoid cells. (12 Dec 1998) |
| mast leukocyte | A polymorphonuclear leukocyte characterised by many large, coarse, metachromatic granules (dark purple or blue-black when treated with Wright's or similar stains) that usually fill the cytoplasm and may almost mask the nucleus; these leukocyte's are unique in that they usually do not occur in increased numbers as the result of acute infectious disease, and their phagocytic qualities are probably not significant; the granules, which contain heparin and histamine, may degranulate in response to hypersensitivity reactions and can be of significance in general inflammation. Synonym: basocyte, basophilocyte, mast leukocyte. (05 Mar 2000) |
| globular leukocyte | A type of wandering cell with a small, round nucleus found in the epithelium and lamina propria of the intestinal mucosa of many animals; its cytoplasm contains large eosinophilic globules or droplets. (05 Mar 2000) |
| granular leukocyte | Any one of the polymorphonuclear leukocyte's, especially a neutrophilic leukocyte. See: granulocyte, basophilic leukocyte, eosinophilic leukocyte. (05 Mar 2000) |
| chemotaxis, leukocyte | The movement of leukocytes in response to a chemical concentration gradient or to products formed in an immunologic reaction. (12 Dec 1998) |