EFFECTS OF INTERFERON-GAMMA ON CELL-DIFFERENTIATION AND CYTOKINE PRODUCTION OF A HUMAN MONOBLAST CELL-LINE, U937

The U937 cell, a human monoblast cell line, has been used as a model t o study the function of human monocytes. We investigated the effects o f interferon-gamma (IFN-gamma) on superoxide anion (O-2(-)) production , cell surface antigens, and cytokine production of U937 cells. IFN-ga mma treatment enhanced O-2(-) production of fMLP or PMA-stimulated U93 7 cells. IFN-gamma increased the ratio of CD23 and CD11b positive cell s. The fluorescence intensity of CD14 and CD25 was enhanced by IFN-gam ma treatment. U937 cells produced IL-1 alpha, IL-1 beta, IL-6, and TNF -alpha by lipopolysaccharide (LPS) stimulation. IFN-gamma treatment en hanced TNF-or production, but decreased IL-6 production. These results suggest that IFN-gamma differentiates U937 cells to monocytelike cell s and it regulates the production systems of IL-6 and TNF-alpha separa tely in U937 cells.