The effect of alpha and gamma interferon on cell growth and histocompatibility antigen expression by human renal carcinoma cells in vitro.

Tumour cells were separated from 19 renal carcinomas and cultured in vitro. The effect of interferon (IFN) alpha and gamma on cell proliferation was measured and compared to the effect of IFN on the expression of class I and class II major histocompatibility complex (MHC) antigens. When tested within the first 14 days of culture, IFN-alpha inhibited protein synthesis in 12 of 15 and IFN-gamma in four of nine tumours. Reduction in cell counts was in parallel. In six tumours the culture period was extended and in all six the effect of IFN-alpha was lost. Exposure to IFN-alpha induced or enhanced class I antigen expression in eight of 19 tumours and class II expression in two of 19. The analogous figures for IFN-gamma were five and three tumours. In four of five cases where a comparison could be made there was a correlation between the effects of IFN-alpha on cell proliferation and class I antigen expression. The efficacy of IFN in the treatment of renal carcinomas may thus, in part, result from inhibition of cell proliferation and enhancement of antigen expression.