Murine leukemia: depressed response to interferon induction correlated with a serum hyporeactive factor.

Mice injected by the intraperitoneal route with either L1210 or P388 leukemic cells progressively developed a state of hyporeactivity to interferon induction that was dependent upon inducer and time of administration. A circulating factor was detected in the serum of both L1210 and P388 leukemic mice that could transfer hyporeactivity to normal murine cells in vitro. A direct relationship existed between the concentration of serum factor and development of hyporeactivity to interferon induction in vivo. Characterization of the serum hyporeactive factor from P388 or L1210 leukemic mice indicated that both were similar to a hyporeactive factor previously detected in serum from virus-infected mice. These results suggest a cause-effect relationship between the serum hyporeactive factor and development of hyporeactivity in vivo.