Systemic Effects of Methylcholanthrene in Mice

Male and female mice of strains C3H/eB and C57BL/6 were injected subcutaneously with methylcholanthrene (MCA) dissolved in olive oil; mice injected with olive oil served as controls. After intervals of from 2 to 13 weeks, experimental and control mice were injected intraperitoneally with 51Cr-labeled rat red cells (RRC) and killed 24 h later. Radioactivity assayed in spleen and liver and expressed as percent of total-body radioactivity served as indicator of phagocytic uptake. Significant decreases in splenic and, to a lesser extent, hepatic phagocytosis were observed at some time intervals in all strain-sex combinations, except for female C57BL/6 mice. The phagocytic activity of untreated C57BL/6 mice exceeded that of C3H/eB mice. Phagocytosis was greater in female than in male C3H/eB mice. In the experimental design employed, no direct correlation was apparent between impairment of phagocytosis and resistance to carcinogenesis.