Antiproliferation and colony-forming inhibition activities of recombinant feline interferon (rFeIFN) on various cells in vitro.

The antiproliferative and colony inhibiting activities of recombinant feline interferon (rFeIFN Type I) against various cells in vitro were examined. Feline and canine cells were both sensitive to rFeIFN. To inhibit the growth of feline cells by 50% approximately 5 x 10(2) to 1 x 10(3) U/mL rFeIFN was required and maximum activity was achieved at a concentration of 1 x 10(5) U/mL. Approximately 5 x 10(3) to 5 x 10(4) U/mL rFeIFN was necessary to inhibit the growth of canine cells by 50%. The antiproliferative and colony inhibiting activities of rFeIFN on canine cells appeared to be cell-specific and dose-dependent. However, human, monkey and hamster cells were resistant to rFeIFN. We suggest that rFeIFN might be useful for treatment of feline and some canine neoplastic conditions.