Combined effects of interferon and mutagens on survival of mouse L929 cells

We studied the effect of mouse interferon (IFN) alpha/beta on the sensitivity of L929 cells to cytotoxic activity of ultraviolet (UV) irradiation or ethyl methanesulfonate (EMS) administration. Exposure of L929 cells to IFN for 48 h before mutagen treatment markedly enhanced their sensitivity to UV, but only slightly to EMS. Incubation of L929 cells after UV-irradiation for 24 h in the presence of low concentrations of IFN (15 units/ml) increased the cellular recovery, while with graded concentrations of IFN the protective activity was inhibited (60 units/ml) and after 250 units/ml the ability of IFN treated cells to recover was found to decrease. Incubation of cells after EMS treatment for 24 h with low (15 units/ml) or moderate (60 units/ml) IFN concentrations markedly reduced the cellular recovery. It has been shown that the extent and the direction of IFN activity on cellular sensitivity to mutagens was influenced by the type of mutagen, IFN-concentration and length of its action on the cell and upon application of IFN before or after mutagen treatment.