The effect of cyclophosphamide, methotrexate and X-irradiation on the ultrastructure and endocytic capacity of murine peritoneal macrophages.

100 mg/kg cyclophosphamide given subcutaneously daily for 5 days and whole-body X-irradiation (500 r) had an appreciable effect on the phagocytosis of E. coli by mouse peritoneal macrophages. Less bacteria were ingested by cells from the treated mice as compared with control cells. In contrast, whole-body X-irradiation had a stimulatory effect on pinocytosis as compared with cells from cyclophosphamide treated mice or control mice. Morphological changes in the cells from animals treated with cyclophosphamide or X-rays were evident. The cells were larger than normal macrophages and contained large amounts of lipid and phagolysosomes and had more vacuoles as compared with control cells. Many giant cells were present in the treated mice. Treatment of mice with methotrexate for 5 days, although affecting the cells morphologically in that they were larger than normal cells and had many vacuoles did not appear to have any effect on either phagocytosis or pinocytosis. Cells from methotrexate treated animals did not contain the large quantities of lipid seen in cells from the cyclophosphamide treated and X-irradiated mice.