Function and role of peritoneal macrophages in experimental leukaemia.

The specific and nonspecific function of peritoneal macrophages of leukaemic mice has been studied as well as the role of these cells in the induction of lymphocyte cytotoxicity against leukaemic cells in vitro. It was found that the phagocytic and digestive function of the peritoneal macrophages remains normal, but the macrophage-mediated cytotoxicity against leukaemic cells is rare and weak in both allogeneic and syngeneic forms of grafted leukaemia. Utilizing the system of generation of cytotoxic lymphocytes in mixed lymphocyte tumour cell cultures in vitro, it was observed that the addition of specifically activated syngeneic macrophages lowers the rate of generated cytotoxicity. The mechanism of macrophage-induced suppression is discussed.