Recombinant Interferon-γ Stimulates the Production of Human Tumor Necrosis Factor In Vitro

Human peripheral blood monocytes in culture secrete tumor necrosis factor (TNF), which can be detected with a sensitive enzyme-linked immunosorbent assay system. When recombinant human interferon-γ (rIFN-γ) is added to cultured cells, TNF production is increased. rIFN-γ is also able to sustain the elevated production level of TNF over a 4-day period. Recombinant interferon-α (rlFN-α) was unable to stimulate increased TNF production. Unstimulated mononuclear phagocytes and rIFN-α-treated cells decreased secretion of TNF over a 4-day interval. The stimulatory effect of rIFN-γ was dose dependent and required both new RNA and protein synthesis and was independent of endotoxin in the tissue culture medium.