[Studies on characteristics of macrophage-derived cytotoxic factor].

Macrophage-derived cytotoxic factor (M phi-CF) obtained from murine peritoneal macrophages stimulated with calcium ionophore A 23187 and lipopolysacchride was characterized. It had a relative molecular mass of 52,000 +/- 3400 Daltons as determined by gel filtration on Sephadex G-100 column. It was stable in a pH range of 6-10, and at 56 degrees C for 1 h. It was sensitive to pronase and trypsin, but its cytotoxicity was not destroyed by pepsin or 2-mercaptoethanol. Protease inhibitors (phenylmethylsulfonyl fluoride, 8-hydroxyquinine, and soybean trypsin inhibitor) had no significant effect on its cytotoxicity. Pretreatment of target cells with 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) protected them from the cytotoxic effect of M phi-CF. These characteristics of M phi-CF are essentially similar to those of tumor necrosis factor (TNF).