The cellular nature of concanavalin A-stimulated antibody-dependent cell-mediated cytotoxicity.

Enhanced antibody-dependent cytotoxic cell (ADCC) activity, generated in vitro by concanavalin A (Con A) stimulation of human peripheral blood lymphocytes, was analyzed to identify the nature of the killer (K) cell. Stimulated and unstimulated 2-day cultured cells were separated into sheep erythrocyte rosetting (E+) and non-rosetting (E-) subpopulations, and ADCC activity was determined by using the slopes of linear dose-response plots as a measure of K cell activity. Quantitative comparisons were made by examining activity on a per cell basis ("specific" activity) and total K cell activity recovered per subpopulation. This analysis revealed that although the E- cells were enriched for specific ADCC activity, the E+ subpopulation contained the major proportion of the total recovered activity and nearly all of the Con A-induced increase in K cell activity.