Coated fibronectin induces adhesion in the human monocytic cell line U937

The differentiation inducing effect of coated human fibronectin (HFN) on U937 was investigated. U937 cells usually proliferate without stimuli. HFN induced the adhesion of about 20% of U937 cells in a serum free medium. HFN did not inhibit cell growth nor induce CD14 expression. The adhesion inducing activity of HFN was completely blocked by addition of anti-HFN antibody. Phorbor 12-myristate 13-acetate (PMA), another differentiation inducing agent, inhibited the growth of U937 cells but did not induce adhesion in the serum free medium. These data imply that HFN has a differentiation inducing effect on a human monocytic cell line and could be used as a biological response modifier.