Effect of immunization with an allogeneic tumor on the growth of primary methylcholanthrene-induced sarcomas in rats

Making use of common antigenicity among allogeneic tumors, the immunotherapy against primary 3-methylcholanthrene(MCA)-induced sarcomas in rats was attempted. At the time when MCA-induced sarcomas reached approximately 1 cm in diameter, allogeneic Usubuchi sarcoma cells were injected 5 times into the subcutaneous tissue of rats. In most cases, inhibitory effect on the growth of the tumor was observed in the early period, but none of 29 cases treated resulted in final regression. Twenty-nine non-treated cases showed uniformly progressive growth from the beginning. This result seems to indicate the possibility of using allogeneic tumor(s) for the immunotherapy against human cancer.

Histologic host response to primary methylcholanthrene-induced sarcomas in rats immunized with allogeneic tumors

Lymphocytic infiltration was observed in 44 of 51 (86%) 3-methylcholanthrene (MCA)-induced sarcomas in rats which had been intensively immunized with allogeneic tumors. Eleven of 29 (38%) tumors with intense lymphocytic infiltration and 5 of 15 (33%) tumors with moderate lymphocytic infiltration were "negative" in autologous transplantation. On the other hand, all of 7 tumors accompanied with slight or no lymphocytic infiltration were "positive".

Further studies on cross-immunity among syngeneic tumors in mice

In the present studies employing 3-methylcholanthrene (MCA)-induced sarcomas of C3H/He mice, cross-immunity among syngeneic tumors was markedly demonstrated by immunization with living tumor cells after repeated inoculation of gamma-irradiated (13, 000 rads 60Co) tumor cells. Cross-immunity was also markedly shown in the challenge of the other MCA-induced tumor, which was induced in the same mouse in which the immunizing MCA-induced tumor originated, by repeated immunization with gamma-irradiated tumor cells only. On the contrary, cross-immunity was not observed between tumors induced on different mice by repeated immunization with gamma-irradiated tumor cells only. As the result of the immunization with gamma-irradiated tumor cells only, common antigenicity among syngeneic tumors seems to be hardly demonstrated, and antigenic indiviDuality among animals, in which MCA-induced sarcomas originated, seems to be remarkably demonstrated.