Specific sensitization of lymphocytes to tumor antigens by co-cultivation with peritoneal cells exposed to such antigens.

Peritoneal cells from BALB/c mice were seeded into 50-mm plastic Petri dishes and exposed either to antigen extracts prepared from individual BALB/c sarcomas having unique tumor-specific antigens, to similar extracts prepared from 14- to 18-day-old mouse embryos, or to culture medium only. Lymphoid cells from BALB/c lymph nodes were than added to the peritoneal cells. Following 4-5 days of co-cultivation, the lymphoid cells were harvested and tested in a 30 h microcytotoxicity assay for reactivity against tumor cells carrying the respective sensitizing antigens as well as against control cells which consisted of either tumor cells lacking the sensitizing antigens or normal skin fibroblasts. By this approach sensitization to individually unique tumor antigens, as well as to antigens shared by mouse embryos and mouse sarcoma cells, was achieved.