Modulation of mitogenic activity of tumor necrosis factor by interferons and dexamethasone.

Effect of interferon (IFN)s on fibroblast growth enhancing activity of tumor necrosis factor (TNF) was examined. IFN-gamma and -beta inhibited TNF-mediated growth stimulation of FS-4 cells. IFNs also inhibited dexamethasone (DEX)-mediated amplification of mitogenic activity of TNF. Significant inhibition was still demonstrable when IFN-gamma was added 2 days after treatment with TNF. On the other hand, no mitogenic activity of TNF was observed when cells were pretreated with IFN-gamma for 6h. These results suggested that interaction between TNF and IFN-gamma might play a role in modulation of some inflammatory processes in vivo.