title: Precursor and effector phenotypes of activated human T lymphocytes.
abstract: In mice, thymus-derived lymphocytes are differentiated into functional subclasses by their cell surface antigens. The Ly 1 determinants are present on T cells with a helper function, whereas Ly 2 and Ly 3 antigens are expressed on the surface of lymphocytes with suppressor or cytotoxic functions. In man also, T-cell subsets have been identified using allo- and heteroimmune sera and, more recently, using monoclonal antibodies, which seem to identify helper and suppressor or cytotoxic subpopulations. The major histocompatibility system (MHS)-encoded Ia antigens belong to several polymorphic families of membrane associated glycoproteins originally found on B lymphocytes; however, they have also been shown to be markers for suppressor T cells in mice. Recent studies have shown that in both mouse and man, T cells activated by a mixed lymphocyte reaction or by mitogens become Ia+. Furthermore, some human T lymphoid cells, either freshly isolated from peripheral blood or after in vitro activation by lectins or alloantigens, possess suppressor properties. We report here the phenotype of a T suppressor-cell subpopulation which was induced in long-term culture of lymphoid cells after activation with phytohaemagglutinin (PHA). Our results suggest that a subset of T cells was progressively expanded over a period of 8 days in culture and that, with the expression on the surface of these cells of 'Ia-like' antigens, they acquired the capacity to suppress the proliferative response of syngeneic or allogeneic lymphocytes to alloantigens or mitogens.
mesh_terms: D000954:Antigens, Surface / Q000032:analysis*; D002478:Cells, Cultured; D006680:HLA Antigens / Q000032:analysis; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D006801:Humans; D007108:Immune Tolerance; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D013601:T-Lymphocytes / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D000954:Antigens, Surface; D006680:HLA Antigens; D000949:Histocompatibility Antigens Class II