title: Identification of phenotypically distinct subpopulations of cytotoxic T lymphocytes.
abstract: Two distinct subpopulations of cytotoxic T lymphocytes (CTL) were identified on the basis of their expression of a marker recognized by a monoclonal antibody H9/25. Conventional bulk mixed lymphocyte reactions (MLR) against either major histocompatibility antigens or minor histocompatibility antigens yield cytotoxic T cells which carry the H9/25 marker (H9/25+). Removal of H9/25+ spleen cells before MLR culture did not prevent the generation of CTL. However, the CTL had the phenotype H9/25-. These results imply that two distinct subpopulations of CTL exist, H9/25+ and H9/25-. Under normal conditions the H9/25+ CTL subpopulation dominates. Removal of H9/25+ spleen cells from the responder spleen cell population before MLR stimulation allows the expression of the otherwise silent H9/25- subpopulation of CTL. The data suggest that H9/25+ spleen cells regulate the expression of CTL subpopulations in bulk MLR cultures.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D010641:Phenotype; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface