Augmentation of cytotoxic activity of recombinant human tumor necrosis factor (rHu-TNF) by recombinant human interferon-gamma (rHu-IFN-gamma).

The present study was undertaken to examine the effect of recombinant human interferon-gamma (rHu-IFN-gamma) on the in vitro antitumor activity of recombinant human tumor necrosis factor (rHu-TNF) against rHu-TNF-sensitive and resistant tumor cells. rHu-IFN-gamma augmented both cytostatic and cytocidal activity of rHu-TNF. When 14 tumor cells were tested, augmentation by rHu-IFN-gamma was observed in most of rHu-TNF-sensitive tumor cells and in few cases in rHu-TNF-resistant tumor cells. Among rHu-TNF-sensitive tumor cells, there was no relationship between the degree of augmentation and the susceptibility to rHu-TNF. Augmentation was marked when tumor cells were treated with rHu-IFN-gamma either before the exposure to rHu-TNF or during the early period of the exposure to rHu-TNF. On the other hand, augmentation was not observed when tumor cells were treated with rHu-IFN-gamma during a late period of the exposure to rHu-TNF. From these results, a combined treatment with both agents can be expected to provide an approach to get better results in clinical trials.