[Direct and indirect antitumor effect of murine recombinant interferons]

The antitumor effects of murine recombinant interferons (beta) and (gamma) against B-16 melanoma and B16-F10 melanoma were examined. In a pharmacokinetic study, intraperitoneal injection of Mu-rIFN (gamma) produced higher and longer detectable IFN activity than administration of Mu-rIFN (beta) in both plasma and organs. In clonogenic assay, Mu-rIFN (gamma) at 1,000 units/ml showed 80% inhibition of colonies of B16-F10 melanoma. However, Mu-rIFN (beta) hardly inhibited the colony formation of B16-F10 melanoma. Furthermore, both IFNs had different characteristics from each other in the augmentation of NK cell and macrophage activities. In the experimental metastasis of B-16 melanoma, the inhibitory effect of Mu-rIFN (beta) on the pulmonary metastasis was mediated by the host defense mechanism, and NK cells and macrophages were important for the inhibition. Mu-rIFN (gamma) showed a stronger effect against B16-F10 melanoma in the inhibition of the growth of sc implanted tumor and artificial metastasis.