Morphological aspects of inhibition of transformation of rat kidney cells infected with a temperature-sensitive mutant of the Rous sarcoma virus by rat fibroblast interferon.

Normal rat kidney cells (NRK) infected with a temperature-sensitive (ts) mutant of Rous Sarcoma virus (RSV) at the permissive temperature (33 degrees C) exhibit the morphological and growth characteristics of the transformed state. By the use of this system, it has been shown that the addition of rat fibroblast interferon to infected cells grown at a nonpermissive temperature (38 degrees C) prevents re-transformation when they are introduced to the permissive temperature. Merely treating cells at the permissive temperature with rat fibroblast interferon causes them to change from the transformed phenotype to a normal phenotype. These effects require the continuous presence of interferon and are quite species specific as observed with the ineffectiveness of mouse fibroblast interferon. Therefore, the results suggest that interferon might restore the growth control of transformed cells which could in part accounts for its anti-tumor effect.