Combination of active and passive immunization and chemotherapy to transplantation of methylcholanthrene-induced tumor in WKA rats.

The combined effect of active and passive immunization with chemotherapy was studied in the treatment of rapidly growing methylcholanthrene-induced fibrosarcoma KMT-17 in the WKA rat. In active immunization, live Friend virus-infected KMT-17 tumor cells were inoculated s.c. into rats a few hr after KMT-17 transplantation. The survival rate with active immunization alone was only 19.0%. In passive immuniza tion, syngeneic lymphoid cells from rats previously immu nized with Friend virus-infected KMT-17 tumor cells were transferred i.v. a few hr after KMT-17 transplantation. The survival rate with passive immunization alone was only 18.2%. With chemotherapy, mitomycin C, 1 mg/kg, was inoculated i.v. 3 days after KMT-17 transplantation. The rate of survival was only 17.4%. However, the combination of active immunization and chemotherapy increased the inhibition of KMT-17 transplantation to 56.0%, while the combination of active and passive immunization brought the survival rate up to 60.9%. Furthermore, the combination of active and passive immunizations and chemotherapy resulted in a survival rate of 84.9%. Also, the lymphoid cells used for passive immunization were not restricted to lymphoid cells obtained from donors immunized with the identical target tumor. When passive immunization was combined with active immunization and chemotherapy, the lymphoid cells for the passive immuniza tion were allowed to be obtained from donors immunized with Friend virus-induced rat tumor WFT-13; this tumor possessed virus-related antigens identical to the newly ac quired antigens on the Friend virus-infected KMT-17 tu mor cells that were used as the immunizing material.