It was found that human recombinant interferon-alpha (Hu rIFN-α) was biologically active in the guinea pig. Namely, intratumor injection of either Hu rIFN-α A or AID regressed tumors and prevented metastasis of guineapig line 10 tumor. These rIFNs augmented splenic natural killer activity of the guinea pig and reduced the cytopathic effect of virus on guinea-pig cells. Hu IFN-Y showed no such activity.
