title: Ia antigen on peripheral blood mononuclear leukocytes in man. II. Functional studies of HLA-DR-positive T cells activated in mixed lymphocyte reactions.
abstract: Blast transformation of T cells in response to allogeneic lymphocytes is followed by expression of HLA-DR antigen on up to 60% of the T cells. Murine monoclonal antibody to HLA-DR antigen was used to separate alloactivated T cells into those T cells that express high quantities of DR antigen (DR+) and those that express little or no DR antigen (DR-), and each population was tested in a variety of assays. DR+, but not DR-, T cells stimulated fresh allogeneic and autologous T cells to proliferate and supported proliferation by fresh autologous T cells to soluble antigens. Alloactivated T cells were suppressive of fresh mixed lymphocyte reactions (MLR) and suppression by irradiated DR+ T cells was specific for the DR antigens of the initial stimulator cell. Suppression of the MLR by DR+ T cells was not a result of altered kinetics or cell-mediated cytotoxicity. DR+ T cells released soluble factors that suppressed fresh allogeneic responses. These data indicate that alloactivated DR+ T cells may provide antigen-specific feedback inhibition of the MLR.
mesh_terms: D000818:Animals; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007111:Immunity, Cellular; D007519:Isoantigens / Q000276:immunology; D007962:Leukocytes / Q000276:immunology*; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000949:Histocompatibility Antigens Class II; D007519:Isoantigens