Cytotoxic effects of alpha- and gamma-interferon and tumor necrosis factor in human bladder tumor cell lines

We investigated the activity of alpha-interferon (-IFN), gamma-interferon (-IFN) and tumor necrosis factor-alpha (TNF-) in a panel of ten human bladder tumor cell lines. All cytokines were tested at concentrations of 100–10000 U/ml in a clonogenic assay system. We found that -IFN was active against five of the ten lines while -IFN was only active against one line. TNF was active against five of the ten lines. Maximum synergisms were obtained between the -IFN and TNF, occurring in nine of the ten cell lines. We conclude that -IFN and TNF are active as single agents and synergistic when used together in vitro in human bladder tumor cell lines.