Suppression of tumor growth in strain 2 guinea pigs by xenogeneic antitumor antibody.

Line 10 hepatoma cells were incubated with antiserum specific against line 10 cells (RaL10) and then tested for growth in syngeneic Wright strain 2 guinea pigs. Palpable tumors appeared in only 11 of 23 animals inoculated id with 10(5) RaL10-treated tumor cells, compared with an incidence of 21 of 23 for nonimmune rabbit serum (NRS)-treated cells and 23 of 23 for cells treated with syngeneic guinea pig serum. Animals inoculated with RaL10-treated tumor cells did not develop systemic tumor immunity. The long-term survival of guinea pigs receiving RaL10-treated tumor cells iv was 6 of 12 with a dose of 10(5) cells and 8 of 11 with 10(4) cells. None of the animals receiving 10(4) or 10(5) control tumor cells treated with NRS survived. RaL10 antiserum was not toxic to line 10 tumor cells in vitro, but mediated tumor-specific cytolytic reactions in the presence of fresh guinea pig serum or on the addition of peritoneal exudate cells from nonimmunized syngeneic guinea pigs.