Distinction of anti-K562 and anti-allocytotoxicity in in vitro-stimulated populations of human lymphocytes

The properties of lymphocytes cultivated with K562 (MKC)—a cell line which lacks HLA antigens and is sensitive to natural cytotoxicity—was compared to conventional mixed lymphocyte cultures (MLC). The characteristics of the two cultures differed. In the MKC there were fewer E positive blasts and more FcR-positive cells, and a higher proportion of the T cells was nylon adherent. The cells of both cultures were cytotoxic against K562. Against the sensitizer alloblasts, MLC populations were regularly more active than lymphocytes derived from the same donor but cultivated with K562. As indicated by the relative cytotoxic efficiencies of MLC subsets, part of the the killer cells affecting K562 and alloblasts differed in the expression of E receptors. Acting similarly to natural killers in the fresh blood, anti-K562 effectors were more abundant in the subsets which did not sediment as SRBC rosettes. In contrast, the specific alloreactivity was more pronounced with the SRBC-rosetting cells.