Lymphocyte subpopulations in man: characterization of human killer cells against allogeneic targets sensitized with HLA antibodies

Human killer cells mediating antibody-dependent cytotoxicity against allogeneic lymphoblasts presensitized with HLA antibodies have been studied by rosette fractionation experiments. Enriched and/or depleted cell suspensions have been tested in dose-response studies. Two different populations can act as killer cells. The major cytotoxic capacity is retained among T cells with high-avidity Fc receptors, whereas a minor cytotoxic capacity was found among non-T cells with high-avidity Fc receptors. These two populations have different dose-response curves, indicating different effector mechanisms.