Effect of Intraperitoneal Injection of Mitomycin C Adsorbed on Activated Carbon Particles on Induction of Cytolytic Peritoneal Macrophages of Mice

The effects of the intraperitoneal injection of mitomycin C adsorbed onto activated carbon particles (MMC‐CH) were assessed on the host immune status and the induction of cytolytic peritoneal macrophages (PM) in mice in comparison with an aqueous MMC solution (MMC‐AQ). PM from inbred C57BL/6 mice and syngeneic B16 melanoma cells were used as the effector and target cells for the PM‐mediated cytotoxicity assay. After a single injection of MMC‐AQ (at the dose of 1/2 LD(50)), the weights of thymus and spleen and the (3)H‐thymidine uptake of spleen cells stimulated by concanavalin A were markedly decreased compared to those following injection of MMC‐CH containing the same dose of MMC. A significant difference was found in the chronological changes of peritoneal exudate cell (PEC) numbers and PM cytolytic activity between the MMC‐AQ‐ and MMC‐CH‐treated mice. One day after MMC‐AQ injection, the PEC numbers were decreased markedly. However, they increased ten‐fold after MMC‐CH injection and the PM cytolytic activity was significantly higher after MMC‐CH injection than after MMC‐AQ injection during the first 3 days. The present results suggest the possible superiority of MMC‐coated charcoal over free MMC both because of a lessening of the effects on host immunity due to prolonged slow drug release and because of the increase in cytolytic macrophages that was induced.