Antiproliferative effects of bacillus Calmette-Guérin and interferon α2b on human bladder cancer cells in vitro.

Direct inhibitory effects of bacillus Calmette-Guérin (BCG) and interferon α2b (IFNα2b) on six human bladder carcinoma cell lines, UCRU-BL-13, UCRU-BL-17, UCRU-BL-28, 5637, T24 and J82, were studied using an in vitro proliferation assay. Effects on proliferation following exposure to BCG or IFNα2b were analysed by [H]thymidine incorporation over 7 days. BCG had an antiproliferative effect on all bladder lines, while sensitivity to IFNα2b varied greatly, being as remarkably low as 1 U/ml for some lines. The antiproliferative effect was greatest when cells were exposed continuously to either agent, but was still evident with a limited exposure. When clinical concentrations were simulated in vitro, BCG+IFNα2b was more effective than BCG alone and as effective as a double BCG concentration. We conclude that, in addition to their immunomodulatory effects, BCG and IFNα2b directly inhibit the proliferation of human bladder cancer cells, and often at extremely low concentrations. [ABSTRACT FROM AUTHOR]