Elimination of polynucleotide-induced hyporeactivity in mice treated with interferon and antitumor therapy.

Polyriboinosinic-polyribocytidylic acid (poly I:C) (100 microgram) induced hyporeactivity to interferon production 24, 48 and 72 hr after the injection. This hyporeactivity was eliminated by the injection of mouse brain interferon (more than 10,000 IU) 3 hr prior to the second injection of poly I:C. Even the hyporeactivity caused by the repeated administration of poly I:C was eliminated when interferon was injected 3 hr before each administration of poly I:C. It was surmised that one of the causes for the elimination of hyporeactivity may be the priming effect effect of interferon in mice. By utilizing the eliminating effect which interferon has on the hyporeactivity caused by poly I:C, the synergistically suppressive effect of interferon and poly I:C on the mortality and tumor growth in the neuroblastoma-bearing mice was found. These results suggest that the combined use of interferon and interferon-inducer may be applicable to cancers or viral diseases in humans.