| integrin modulating factor 1 | <chemical> A lipid that alters the function of leukocyte integrins; may be an unsaturated fatty acid or an isoprenoid acid Synonym: imf 1, imf-1 (05 Dec 1998) |
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| intrinsic factor | A mucoprotein normally secreted by the epithelium of the stomach and that binds vitamin B12, the intrinsic factor/B12 complex is selectively absorbed by the distal ileum, though only the vitamin is taken into the cell. (18 Nov 1997) |
| osteoclast activating factor | A lymphokine that stimulates bone resorption and inhibits bone-collagen synthesis. (05 Mar 2000) |
| T-cell growth factor | <cytokine> A hormone-like substance released by stimulated T lymphocytes, causes activation and differentiation of other T lymphocytes independently of antigen. A type of interleukin, a chemical messenger, a substance that can improve the body's response to disease. It stimulates the growth of certain disease-fighting blood cells in the immune system. It is secreted by Thl CD4 cells to stimulate CD8 cytotoxic T-1yrnphocytes. Interleukin 2 also increases the proliferation and maturation of the CD4 cells themselves. During HIV infection, Interleukin-2 production gradually declines. Use of interleukin 2 therapy is under study as a way to raise CD4 cell counts and restore immune function. Acronym: IL-2 (12 Dec 1998) |
| T-cell growth factor-1 | <cytokine> A hormone-like substance released by stimulated T lymphocytes, causes activation and differentiation of other T lymphocytes independently of antigen. A type of interleukin, a chemical messenger, a substance that can improve the body's response to disease. It stimulates the growth of certain disease-fighting blood cells in the immune system. It is secreted by Thl CD4 cells to stimulate CD8 cytotoxic T-1yrnphocytes. Interleukin 2 also increases the proliferation and maturation of the CD4 cells themselves. During HIV infection, Interleukin-2 production gradually declines. Use of interleukin 2 therapy is under study as a way to raise CD4 cell counts and restore immune function. Acronym: IL-2 (12 Dec 1998) |
| T-cell growth factor-2 | <cytokine> A soluble cytokine factor produced by activated T-lymphocytes that promotes antibody production by causing proliferation and differentiation of B-cells. Interleukin-4 induces the expression of class II major histocompatibility complex and fc receptors on B-cells. It also acts on T-lymphocytes, mast cell lines, and several other haematopoietic lineage cells including granulocyte, megakaryocyte, and erythroid precursors, as well as macrophages. Acronym: IL-4 (12 Dec 1998) |
| termination factor | <molecular biology> Any of several proteins in the cytosol that cut a completed polypeptide loose from a ribosome. (13 Jan 1998) |
| testis-determining factor | The product of a gene on the short arm of the Y chromosome that is responsible for production of testes. (05 Mar 2000) |
| thymic factor, circulating | <chemical> A thymus-dependent nonapeptide found in normal blood. Stimulates the formation of e rosettes and is believed to be involved in T-cell differentiation. Chemical name: Thymulin (12 Dec 1998) |
| thymic lymphopoietic factor | A glycoprotein (MW about 12,000) that has been extracted from thymus; this thymus-produced hormone(s) confers immunological competence on thymus-dependent cells and induces lymphopoiesis. (05 Mar 2000) |
| thyrotoxic complement-fixation factor | A form of thyrotoxin; an antigen found most readily in thyroid tissue from thyrotoxic individuals; known to be chemically and immunologically distinct from thyroglobulin, and fixes complement when combined with antibody related to the gamma-globulin fraction of serum. With the exception of extremely small concentrations, the antigen is rarely found in normal glands or in diseased glands that are not associated with thyrotoxicosis; it is probably an intracellular substance (possibly a constituent of the "microsomal fraction"), and does not contain iodine in significant quantity. Not related to the complement-fixation reaction occurring with serum in Hashimoto's disease, in which the antigen is thyroglobulin. (05 Mar 2000) |
| thyrotropin-releasing factor | Former name for thyrotropin-releasing hormone. (05 Mar 2000) |
| tissue factor | <cell biology> Integral membrane glycoprotein of around 250 residues, that initiates blood clotting after binding factors VII or VIIa. (18 Nov 1997) |
| tissue weighting factor | In radiation protection, a factor weighting the equivalent dose in a particular tissue or organ in terms of its relative contribution to the total deleterious effects resulting from uniform irradiation of the whole body. See: effective dose. (05 Mar 2000) |
| elongation factor | <biochemistry> Peptidyltransferase components of ribosomes that catalyse formation of the acyl bond between the incoming amino acid residue and the peptide chain. There are three classes of elongation factor: EF1_ (EF Tu in prokaryotes) binds GTP and aminoacyl tRNA, delivering it to the A site of ribosomes. EF 1_ (EF Ts) helps in regeneration of GTP EF 1_. EF 2 (EF G) binds GTP and peptidyl tRNA and translocates it from the A site to the P site. Diptheria toxin inhibits protein synthesis in eukaryotes by adding an ADP ribosyl group to a modified histidine residue (dipthamide) in elongation factor II. (18 Nov 1997) |