Cytolytic action of 60-F derived from live hemolytic streptococci against Ehrlich carcinoma cells

The effect of 60-F, a fraction obtained by 0.5 approximately 0.6 saturation of ammonium sulfate of streptomycin-pretreated cell-free extract from live hemolytic streptococci (avirulent Su strain), on release of 51Cr from the 51Cr-labeled Ehrlich ascites carcinoma cells was studied with following results: a) 60-F was found to be highly effective in releasing 51Cr from 51Cr-labeled Ehrlich ascites carcinoma cells. b) Additionally, destructive picutres of the tumor cells contacted with 60-F in vitro was observed by phase-contrast microscopic examination. c) Indication was that the 51Cr-releasing assay method is also useful for the study of the direct cytolytic effect of 60-F.