Mechanisms of specific and non-specific tumour immunity after azathioprine treatment of mice.

The ability of phagocyte-depleted spleen cells to lyse chicken erythrocytes (CRBC) in the presence of antibody was measured in mice which had been treated with the antimetabolite azathioprine. Single doses of the drug had no effect on this ability when measured on the day after administration. A 4-day course of 80 mg/kg/day of the drug markedly reduced splenic antibody-dependent cell-mediated cytotoxicity (ADCMC) although it reduced neither antibody responses nor the development of cytotoxic cells following subsequent immunization with an allogeneic tumour. Splenic phagocytosis and phagocyte-mediated ADCMC were both slightly enhanced following drug treatment. The implications of these findings are that the major antibody-dependent cytotoxic cell in phagocyte-depleted mouse spleen is normally in a state of proliferation, and plays no important role in antigen recognition.