Increased survival in mice inoculated with tumor cells and treated with interferon preparations

Repeated administration of potent mouse interferon preparations increased the survival of Balb/c and C 57/B1(6) mice inoculated with 2,000-3,000 RC(19) and EL(4) tumor cells. Only 7/188 (3.7%) untreated mice (or mice treated with control preparations) survived more than 22 days after intraperitoneal inoculation of RC(19) tumor cells. None survived more than 60 days. In contrast, 101/103 (98%) interferon-treated mice survived beyond 22 days, and sixteen (15%) survived more than 60 days. None of these 16 surviving mice show any sign of tumor at present. Three mice (of the 16) from an early experiment are alive ten months after inoculation of RC(19) tumor cells. Mouse interferon preparations derived from three different tissue sources- brain, serum, and monolayer cell cultures (with Newcastle disease virus and West Nile virus as interferon-inducing agents)-all proved effective. A purified preparation of mouse brain interferon was as effective as crude brain interferon. Human amniotic membrane interferon and control tissue preparations were without effect. These findings suggest that interferon itself (or a factor closely associated with interferon) is the active moiety in these preparations.