Presence and characterization of lymphokines in mouse ascites tumor fluids

Considerable skin-reactive and macrophage-disappearance-inducing activities were detected in cell-free fluids of 2 mouse ascites tumors (Ehrlich ascites tumor, leukemia L 1210). Fractionation of the supernatants by ammonium sulfate precipitation, gel filtration on Sephadex G-200, and DEAE-Sephadex A-50 column chromatography resulted in characterization of the proteinaceous substance which accounts for skin-reactive activity. The factor responsible bears a close physicochemical and biological resemblance to the skin-reactive factor of lymphocytic origin which is known to be generated by specific or nonspecific stimulation of lymphocytes in vitro, or to be produced spontaneously by lymphoblastoid cell lines. The biological significance of the findings is discussed.