Characteristics of antiviral and anticellular activities of human recombinant interferon-gamma.

The antiviral and anticellular activities of recombinant human interferon-gamma (Re-IFN-gamma) were compared with those of natural human interferon-gamma (IFN-gamma), natural human interferon-alpha (IFN-alpha), and recombinant human interferon-beta (ReIFN-beta). ReIFN-gamma and IFN-gamma induced the antiviral state in FL cells against Sindbis virus more rapidly than IFN-alpha or ReIFN-beta. The antiviral state induced by a short exposure time to IFN-gamma declined rapidly after the removal of IFN-gamma and the incubation of FL cells in fresh medium, whereas that induced by ReIFN-gamma was persistent. However, other characteristics of the antiviral activity of ReIFN-gamma were shown to be very similar to those of IFN-gamma (e.g., stability at 56 degrees or pH 2.0, and neutralization by anti-IFN serum). The anticellular spectrum of ReIFN-gamma or IFN-gamma against 26 human cell lines differed in some respects from that of IFN-alpha or ReIFN-beta, since ReIFN-gamma and IFN-gamma were more effective at inhibiting the growth of human carcinoma or sarcoma cell lines. The IC50 (IFN concentration required for 50% growth inhibition) values of ReIFN-gamma were several times smaller than those of IFN-gamma in all cell lines sensitive to both IFNs. ReIFN-gamma and IFN-gamma, but not IFN-alpha or ReIFN-beta, were cytotoxic against HeLa S3 cells. These cytotoxicities of both IFNs were inactivated by treatment at 56 degrees or pH 2.0 and by anti-ReIFN-gamma serum. These results indicate that the characteristics of antiviral and anticellular activities of ReIFN-gamma are somewhat different from those of other IFNs including IFN-gamma.