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 LD50), the weights of thymus and spleen and the 3H-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.