Effects of interferon on growth rate and radiation sensitivity of cultured, human glioma cells.

The influence of interferon (IFN) on the growth rate and on the radiation sensitivity of 2 human tumour cell lines was investigated. The 2 glioma cell lines (U-118 MG and U-251 MG) were continuously exposed to IFN (100 U/ml) in the culture medium. Irradiation (3 Gy) was performed either on the first day of IF treatment or on day 14 of IFN treatment. The growth delay induced by the treatments was analysed. The results indicated that IFN had an anti-proliferative effect on the 2 cell lines. However, this effect declined during the treatment and after 2 to 3 weeks of continuous IFN treatment, both cell lines had re-established their original growth rate. IFN did not seem to affect the sensitivity of the cells to radiation. Only an additive effect could be observed.