Lymphokine properties of a lymphoid cultured cell supernatant fraction active in promoting tumor regression

Abstract In the present study supernatant culture medium from a cultured human lymphoid cell line, which was shown to have inflammation-inducing and tumor-regressing properties in man, was tested for lymphokine properties. Skin reactive factor, lymphotoxin, macrophage activation factor, and chemotactic factor were assayed and found to be present in the crude, active fraction that was confined to a size of 10 4 –10 5 daltons and was active in producing clinical tumor lesion regression. These results suggest that the in vivo antitumor effect is related to lymphokines present in the active preparation.