Specific anti‐tumor responses by cultured immune spleen cells. II. Culture supernatants induce specific anti‐tumor cytotoxicity by non‐immune lymphoid cells in vitro

Sera from tumor‐bearing mice induce specific cytotoxicity to tumor cells by non‐immune lymphoid cells (antiserum‐dependent cytotoxicity or ADC). When spleen cells from BALB/c mice bearing autochthonous or syngeneic sarcomas were cultured in vitro, culture supernatants were obtained which specifically sensitized sarcoma cells to injury in vitro by normal lymph‐node cells (LNC). Culture supernatants of spleen cells from mice whose transplanted sarcomas had been excised also induced ADC. The ADC activity resided in the mouse immunoglobulin fraction of the culture supernatants and its synthesis did not depend on the presence of theta‐positive cells. Following a brief in vivo exposure to culture supernatant with known ADC activity, LNC from non‐immune mice specifically destroyed tumor cells in an in vitro assay.