[Enhancement of the antitumor transplantation resistance in rats by the antileukemia drug busulfan (author's transl)].

Enhancement of antitumor transplantation immunity was observed in rats by treatment with the antileukemia drug busulfan (BU) both 5 days before and 5 days after immunization with X-irradiated tumor cells. The mechanism of the enhancement induced by BU may be due to a selective elimination of the suppressor cells from the immunized host. Similar enhancement of immunity was also observed by using other anticancer drugs when only cyclophosphamide (40 mg/kg) was given before the immunization and futraful (300 mg/kg) and mitomycin c (1 mg/kg) were given offer the immunization. However, adriamycin (4 mg/kg) did not show any enhancing effects on immunity either before or after the immunization.