A FACTOR INDUCING DIFFERENTIATION OF THE HUMAN MONOCYTIC CELL LINE U-937 PRODUCED BY 12-O-TETRADECA-NOYLPHORBOL 13-ACETATE-TREATED U-937

Abstract

A new factor capable of inducing differentiation of human leukemic cell line U-937 into macrophages was found and partially purified from the conditioned medium of U-937 previously treated with 12-O-tetradecanoylphorbol 13-acetate. The purification procedure included ultrafiltration, DEAE-Sephacel and butyl-Toyopearl column chromatography. The purified factor gave a major band of protein with a molecular weight of 67, 000 daltons which coincided with the biological activity of differentiation-inducing factor, and it was not adsorbed on a concanavalin A column. These results suggest that this factor is distinct from other differentiation-inducing factors.