Specific stimulatory and cytotoxic effects of lymphocytes sensitized in vitro to either alloantigens or tumor antigens.

Lymph node cells (LNC) or spleen cells from normal BALB/c mice were sensitized in vitro by co-cultivation with mitomycin C-treated allogeneic sarcoma cells, and their reactivity measured with a microcytotoxicity assay. Following 5 days of sensitization, a specific cytotoxic effect against tumor cells carrying the sensitizing alloantigens was observed; this is in agreement with previously published findings. Lymphoid cells tested after 3 days of sensitization, however, specifically increased the number of target cells remaining in the Microtest plates at the conclusion of the microcytotoxicity assays. LNC from normal BALB/c mice were also sensitized in vitro against tumor specific antigens using four different methylcholanthrene-induced sarcomas of BALB/c origin. After 6 days of sensitization the LNC were specifically cytotoxic for the immunizing tumor cell line. After 3 days of sensitization, however, the LNC gave a specific increase of the number of remaining target tumor cells.