title: Spontaneous and alloantigen-induced cytotoxicity by human T-lymphocyte subpopulations.
abstract: Freshly isolated human T lymphocytes were separated into two subpopulations on the basis of their ability to form E rosettes after treatment with the phosphodiesterase inhibitor, theophylline. T cells that retained the ability to form E rosettes (T-res cells) and those that failed to form E rosettes (T-sens cells) were assayed for natural killer (NK) cell activity against 51Cr-labeled K562 tumor cells and for the ability to proliferate and kill allogeneic cells in mixed-lymphocyte culture (MLC). T-sens cells were highly enriched for NK activity. In contrast, T-res cells exhibited much less activity than either T-sens or unseparated T cells (T-sens greater than unseparated T cells approximately equal to unseparated PBL approximately equal to non-T cells greater than T-res cells). T-sens cells were poorly responsive to allogeneic cells in proliferation assays and demonstrated greater levels of cytotoxicity against allogeneic cells than T-res cells. T cells stimulated with allogeneic lymphocytes for 7 days were cytotoxic for K562 targets while comparably stimulated non-T cells and T cells cultured with medium were not cytotoxic. Cold target inhibition experiments suggested that within the T-sens subset there are overlapping populations which mediate cytotoxicity against K562 and allogeneic cells. These studies demonstrate that freshly isolated human T cells are composed of heterogeneous populations which differ in their ability to mediate NK and to generate cytotoxic T lymphocytes in culture.
mesh_terms: D001667:Binding, Competitive; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D006801:Humans; D007519:Isoantigens / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation / Q000187:drug effects; D007959:Lymphocyte Culture Test, Mixed; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000145:classification / Q000187:drug effects / Q000276:immunology*; D013806:Theophylline / Q000494:pharmacology
chemical_list: D007519:Isoantigens; D013806:Theophylline