title: Characterization of human K cells by surface antigens and morphology at the single cell level.
abstract: Human lymphocytes killing bovine erythrocytes in vitro in antibody-mediated reactions were characterized at the effector cell level in the ADCC plaque assay. Five to 10% of highly purified peripheral blood lymphocytes are active K cells in this system. Forty to 50% of these were T gamma cells expressing the T cell-associated surface antigens T3 and Leu-1. These cells also expressed the T8/Leu-2a antigens (approximately 20%) or the T4/Leu-3a antigens. Although approximately 30% of the K cells were T4+ when examined after completion of the ADCC assay (18 hr), only less than 10% were T4+ (and Leu-3a+) when examined before the assay. The results indicated that exposure to antigen/antibody complexes during the assay induced increased T4 expression, probably linked to Fc gamma R modulation on some initially T4-/T3+ lymphocytes. The expression of the other antigens (including Leu-3a) was not affected by exposure of the lymphocytes to antigen/antibody complexes. Two-color fluorescence experiments further demonstrated that a minor fraction (10 to 20%) of the K cells carrying T cell-associated antigens also expressed the monocyte/null cell-associated antigen M1 as detected with the monoclonal antibody OKM1. A second major category of effector cells, composed of at least 25% of the K cells, were large granular lymphocytes (LGL) that lacked detectable T cell-associated antigens but expressed the HNK-1 (Leu-7) as well as the M1 antigen. As seen from the size of the plaques formed by different effector cells, K cells of the LGL type had a greater recycling capacity and/or cytolytic efficiency than those of T gamma type.
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000502:physiology; D000920:Antibody-Dependent Cell Cytotoxicity; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis* / Q000276:immunology; D002469:Cell Separation; D003165:Complement System Proteins / Q000502:physiology; D006801:Humans; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D008212:Lymphocyte Depletion; D011961:Receptors, Fc / Q000032:analysis; D017452:Receptors, IgG
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D011961:Receptors, Fc; D017452:Receptors, IgG; D003165:Complement System Proteins