title: Stimulation of T cells via the TAP molecule, a member in a family of activating proteins encoded in the Ly-6 locus.
abstract: T-cell activating protein, TAP, is a Ly-6 encoded 12,000 dalton glycoprotein involved in the activation of murine T cells. TAP is distinct from other known surface activating structures, such as the T cell receptor/T3 complex and Thy-1. This study investigates the mechanism of activation via the TAP molecule. Soluble alpha TAP monoclonal antibody (MAb) is sufficient for T cell activation. This, however, requires cross-linking because F(ab) monovalent antibody is not stimulatory unless cross-linked by a second antibody. Immediately after cross-linking, there is a rapid influx of calcium, which is comparable with concanavalin A or T cell receptor triggered responses. Subsequently, interleukin 2 (IL 2) is produced, and IL 2 receptors (IL 2R) are expressed. TAP-stimulated T cell proliferation is driven by this autocrine pathway because it is inhibited by alpha IL 2R MAb. Thus TAP-mediated activation appears to share a common final pathway with other mitogenic stimuli. A nonactivating alpha TAP MAb was observed to stimulate T cells upon additional cross-linking. Given this observation, we asked whether other Ly-6 linked proteins might share similar activating potential. We show that at least three distinct Ly-6 linked molecules are capable of stimulating T hybrid clones and/or heterogeneous T lymphocytes. Thus it appears that the Ly-6 locus encodes a family of activating cell surface molecules.
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D000950:Antigens, Ly / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology*; D002118:Calcium / Q000502:physiology; D003432:Cross-Linking Reagents; D003593:Cytoplasm / Q000502:physiology; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000502:physiology; D008565:Membrane Proteins / Q000276:immunology; D051379:Mice; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D011971:Receptors, Immunologic / Q000378:metabolism; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000276:immunology*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000950:Antigens, Ly; D000954:Antigens, Surface; D003432:Cross-Linking Reagents; D008222:Lymphokines; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D002118:Calcium