Inhibition of anticellular activity of mouse gamma interferon by an inhibitor of interferon action.

An inhibitor of interferon's (IFN) antiviral action was evaluated for its ability to block interferon's anticellular action. Crude and partially purified mouse immune interferon (MuIFN-gamma) preparations with high and low levels of an inhibitor of IFN's antiviral action were prepared. These preparations were examined for their relative antiviral and direct anticellular activities. The inhibitor present in the IFN-gamma preparations was found to be an equally potent inhibitor of both the antiviral and the direct anticellular activities of IFN-gamma. Further, while the inhibitor of IFN-gamma was inherently present in most IFN-gamma preparations, it was not an inherent feature of all IFN-gamma molecules. Inhibitor-free IFN-gamma could be separated from inhibitor-containing IFN-gamma by column chromatography. The results suggest that the inhibitor generally antagonizes interferon action and should be taken into account when evaluating the biological properties of IFN-gamma preparations.