A Comparison of the Effector Cells Involved in Cell‐Mediated Lympholysis and Antibody‐Dependent Cell‐Mediated Cytotoxicity in Man

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Abstract
Some physical and mechanistic properties of cytotoxic lymphocytes and antibody‐dependent killer tells were compared. Cytotoxic lymphocytes were measured by the cell‐mediated lympholysis (CML) technique after sensitization of human peripheral blood leukocytes (PBL) in unidirectional mixed leukocyte culture (MLC). Kilter cells were measured before and after MLC in an antibody‐dependent cell‐mediated cytotoxicity (ADCMC) assay using 51Cr‐labeled mouse mastocytoma cells as targets Quantitative analysis of the cytotoxic activity of populations separated by velocity sedimentation at 1 g indicated that cytotoxic lymphocytes in MLC were a relatively heterogeneous population of rapidly sedimenting cells that corresponded morphologically to lymphoblasts Further studies in which PBL were separated before MLC suggested that such cytotoxic lymphocytes were derived from small lymphocyte progenitors. Analysis of ADCMC in separated populations showed that most killer cells in PBL had the sedimentation properties of small lymphocytes After stimulation of PBL in MLC. increased ADCMC activity was detected, and the increased activity was associated with a population of rapidly sedimenting cells. Comparison of the sensitivity of cytotoxic lymphocytes and killer cells to inhibition by EDTA, cytochalasin B, and dimethyl sulfoxide showed no significant differences between the two types of effector cells.