The effects of adriamycin and daunomycin on antitumoral immune effector mechanisms in an allogeneic system

C3H mice pretreated with adriamycin (AM) 24 hr before transplantation with the allogeneic L1210 leukemia had a significantly longer survival than mice given an equitoxic dose of its analog daunomycin (DM). The effect of the two drugs on cellular and humoral immune effector mechanisms was thus investigated. The longer surviving AM-pretreated tumor allografted mice were found to have higher levels of cell-mediated cytotoxicity (CMC) in the peritoneal cavity, e.g., at the site where tumor growth was actually occurring. On the contrary when spleen CMC was investigated, either no differences were seen or DM-hosts had higher cytotoxic activity. DM was also found to cause a faster impairment than AM of the spleen capacity to mediate antibodydependent cellular cytotoxicity (ADCC). As regards humoral responses, serum complement-dependent and arming activity were absent in both test groups, whereas higher levels of potentiating activity were found in AM pretreated hosts. The possible significance of the lower impairment of antitumoral immune effector mechanisms in giving AM its superior antineoplastic effectiveness is discussed.