Cytotoxic and antitumor activity of a soluble fraction of Streptococcus pyogenes against S180 sarcoma cells.

A fraction (60F) having cytotoxic and antitumor activities was obtained from cell-free extract of group A Streptococcus pyogenes by precipitating with 50% to 60% saturated ammonium sulfate. 60F showed cytotoxic activity inhibiting the uptake of 3H-thymidine by S180 sarcoma cells and enhancing 51Cr-release from 51Cr-labeled cells. 60F showed also antitumor activity, depressing tumor growth and prolonging lives of mice bearing S180 sarcoma cells.