title: A novel pathway of human T cell activation via a 103 kD T cell activation antigen.
abstract: A novel triggering signal for human proliferating and cytotoxic T lymphocytes defined by a 103 kD T cell-specific activation antigen (Tp103) is described. Tp103 is expressed on all proliferating normal T cells but is not present, or present only in low amounts, on resting peripheral blood T lymphocytes. Cross-linking of T cell and Fc receptor-positive accessory or target cells by an antibody against Tp103 leads to activation of the T cell. The proliferative response is due to an autocrine IL 2-dependent mechanism and can be inhibited by antibodies against the IL 2 receptor or by Cyclosporin A. Resting Tp103-positive T cells also respond to anti-Tp103. Although Tp103 is not linked to the antigen receptor/T3 complex, triggering via Tp103 can be inhibited by modulation of the T3 molecule. Thus, Tp103 defines a new antigen-independent pathway of T cell activation that can be regulated via other T cell surface structures.
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000276:immunology*; D002455:Cell Division; D002462:Cell Membrane / Q000276:immunology; D006801:Humans; D007376:Interleukin-2 / Q000502:physiology; D008213:Lymphocyte Activation; D008970:Molecular Weight; D011971:Receptors, Immunologic / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D007376:Interleukin-2; D011971:Receptors, Immunologic