title: The human T lymphocyte receptor complex for antigen and MHC.
abstract: Recent studies using cloned antigen specific T lymphocytes and monoclonal antibodies directed at their various surface glycoprotein components have led to identification of the human T cell antigen receptor as a surface complex comprised of a clonotypic 90 KD Ti heterodimer and the in-variant 20 and 25 KD T3 molecules. Approximately 30,000-40,000 Ti and T3 molecules exist on the surface of human T lymphocytes. These glycoproteins are acquired and expressed during late thymic ontogeny, thus providing the structural basis for immunologic competence. The alpha and beta subunits of Ti bear no precursor-product relationship to one another and are encoded by separate germline V, D, J and C segments which rearrange during intrathymic differentiation to form an active gene set. Triggering of the T3-Ti receptor complex induces a rapid increase in free cytoplasmic Ca2+ and gives rise to specific antigen-induced proliferation through an autocrine pathway involving endogenous IL-2 production, release, and subsequent binding to IL-2 receptors. The implications of these findings for understanding of human T cell growth and its regulation in disease states are discussed.
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002999:Clone Cells / Q000276:immunology; D005796:Genes; D006801:Humans; D007376:Interleukin-2 / Q000502:physiology; D008213:Lymphocyte Activation; D046911:Macromolecular Substances; D008285:Major Histocompatibility Complex; D008565:Membrane Proteins / Q000378:metabolism; D008970:Molecular Weight; D011487:Protein Conformation; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000648:ultrastructure; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000648:ultrastructure; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology / Q000648:ultrastructure
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D007376:Interleukin-2; D046911:Macromolecular Substances; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell