Augmentation of the human monocyte/macrophage chemiluminescence response during short-term exposure to interferon-gamma and tumour necrosis factor-alpha

The effects of short-term (30 min) pre-incubation of human monocytes and macrophages (3-day cultured monocytes) with leucocyte-derived human interferon-gamma (IFN-γ) and recombinant human tumour necrosis factor-alpha (rTNF-α) were examined. Pre-incubation of either monocytes or macrophages with rTNF-α or IFN-γ (100 U/5 x 10⁵ cells) augmented their respiratory burst to formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), measured by the luminol- and lucigenin-dependent chemiluminescence assay. In addition, both cell types showed a burst of respiratory activity in the presence of rTNF-α or IFN-γ only. The effects of IFN-γ were removed by adsorption with an anti-IFN-γ monoclonal antibody and those of rTNF-α were abolished by heating at 100°C, or by the addition of anti-TNF-α monoclonal antibody. The results demonstrate that both IFN-γ and rTNF-α are stimulators of monocytes and macrophages, and rapidly alter the capacity of the cells to respond to fMLP, which binds to cell surface receptors.