Cytotoxic activity of guinea-pig lymph node cells stimulated in vitro

Guinea-pig lymph-node cells (LNC) cultured for 5 days in medium containing fetal calf serum (FCS) were cytotoxic to various target cells. LNC cultured in medium supplemented with fresh, autologous guinea-pig serum (GPS) instead of FCS were not detectably cytotoxic unless agents that stimulate lymphocyte proliferation were added to the culture medium. The stimulating agents we studied were 2-mercaptoethanol (2-ME), syngeneic tumor cells, allogeneic peritoneal exudate cells (PEC) and the T-cell mitogens concanavalin A (Con A) and phytohemagglutinin (PHA). LNC cultured in the presence of these agents were cytotoxic to normal syngeneic fibroblasts and to syngeneic, allogeneic or xenogeneic tumor cells but not to PHA-induced lymphoblasts. Potentiation of cytotoxicity in vitro was accompanied by a marked proliferation of the cultured LNC; the combination of several stimulatory agents had an additive effect on the generation of cytotoxicity in culture.