Tumor necrosis factor receptors in HeLa cells and their regulation by interferon-gamma

Incubation of HeLa cell cultures with human interferon-gamma (IFN-gamma) increased the binding of radioiodinated human tumor necrosis factor (TNF) to specific cell surface receptors (TNF-R). IFN-gamma also produced a proportionate increase in receptor-mediated endocytosis of TNF. TNF-R expression was significantly increased after 6 h of exposure to IFN-gamma (100 units/ml), and it remained elevated in the continuous presence of IFN-gamma for at least 20 h. Incubation of cells with IFN-gamma in the presence of cycloheximide, followed by treatment with actinomycin D and reversal of the inhibition of protein synthesis, also resulted in increased TNF-R expression as compared to cultures subjected to the same treatments in the absence of IFN-gamma. These results suggest that IFN-gamma can directly stimulate accumulation of the mRNA for TNF-R and that TNF-R is among the cellular proteins whose synthesis is increased by IFN-gamma.