Cross-resistance to human interferon-gamma of human interferon-beta-resistant F-IFr cells.

F-IFr cells, which are more resistant to the anticellular and antiviral action of human alpha and beta interferons (IFN-alpha and IFN-beta) than the parental RSa cells, were also found to be more resistant to both the anticellular and antiviral effect of IFN-gamma. A high level of 2-5A synthetase was induced by treatment with IFN-alpha or -beta, but induction of 2-5A synthetase was not detected after IFN-gamma treatment of the cells. F-IFr cells had less than half the number of specific binding sites for IFN-alpha than the parental RSa cells.