The Effect of IFN-γ and TNF-α on the NADPH Oxidase System of Human Colostrum Macrophages,Blood Monocytes,and THP-1 Cells

Abstract

The aim of this work was to analyze the effect of Interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) on NADPH oxidase activity and gp91-phox gene expression in human colostrum macrophages (CM), peripheral blood monocytes (PBM), and myelomonocytic THP-1 cells. We also investigated the effect of IFN-γ on the release of TNF-α by these cells. Our results show that under basal culture conditions, CM release more superoxide than PBM and THP-1 cells (p < 0.05). The addition of IFN-γ, alone or in combination with TNF-α, increased spontaneous superoxide release by PBM and THP-1 cells (p < 0.05) and increased phorbol myristate acetate (PMA)-stimulated superoxide release by CM, PBM, and THP-1 cells (p < 0.05). The NADPH oxidase activity of THP-1 cells consistently remained lower than that of CM or PBM, despite a dramatic response to IFN-γ and TNF-α. Under basal conditions, gp91-phox gene expression was significantly higher in CM and PBM compared with THP-1 cells (p < 0.05). The addition of IFN-γ alone or in combination with TNF-α caused a dramatic increase in gp91-phox gene expression in THP-1 cells (p < 0.05) but not in CM or PBM. Under basal conditions or in the presence of IFN-γ, CM released more TNF-α than PBM or THP-1 cells (p < 0.05). In addition, PBM released more TNF-γ than THP-1 cells (p < 0.05). IFN-γ did not significantly augment the release of TNF-α by these cells (p > 0.05). Thus, IFN-γ and TNF-α induced equivalent gp91-phox gene expression in THP-1 cells compared with CM or PBM but did not bring about equivalent NADPH oxidase activity. TNF-α release was higher in more mature cells. This partial divergence of gp91-phox gene expression, NADPH oxidase activity, and TNF-α release is probably a consequence of different events of myeloid cell biology and relates at least in part to cell differentiation state.