Effect of interferon-γ and 1α,25-dihydroxyvitamin D3 on superoxide anion, prostaglandins E2, and mononuclear cell factor production by U937 cells

Both interferon-γ (IFN-γ) and 1α,25-dihydroxyvitamin D 3 (1α,25(OH) 2 D 3 ) induce changes in the human monocytic cell line U937 that may reflect cellular differentiation. The effects of recombinant IFN-γ and 1α,25(OH) 2 D 3 on U937 cells with regard to the release of Superoxide anion (O 2 − ), prostaglandin E 2 (PGE 2 ), and mononuclear cell factor (MCF) after stimulation with phorbol myristate acetate (PMA) were examined. PMA did not induce O 2 − production in untreated cells. A 3-day preincubation with IFN-γ or 1α,25(OH) 2 D 3 resulted in a 5- to 10-fold increase in PMA-stimulated production of O 2 − as compared to cells preincubated in medium alone. The response was related to IFN-γ and 1α,25(OH) 2 D 3 concentrations. In contrast, the PMA-induced production of PGE 2 and MCF does not require preincubation with either IFN-γ or 1α,25(OH) 2 D 3 . These results suggest that O 2 − production and cytokine production (i.e., PGE 2 and MCF) are modulated by different signals related to maturation processes.