Platelet-derived growth factor (PDGF) inhibits antiviral and anticellular actin of interferon in synchronized mouse or human cells.

Antiviral and anticellular action of purified mouse or human interferon was found to be inhibited in the quiescent, monolayer cultures of mouse or human fibroblasts (3T3 and FS-14) stimulated for growth by PDGF. In the asynchronous cell cultures the antagonistic effect of PDGF towards interferon, was much less evident. The optimal synchronization of cells for division was obtained by density inhibition and the incubation of the confluent cell monolayers in the low serum medium for 24 h and in 5% platelet poor plasma serum (PPPS) medium for further 24 h at 37 degrees C. Under appropriate conditions also pure epidermal growth factor (EGF) and fibroblast growth factor (FGF) acted as antagonists of interferon. It is suggested that interferons and growth factors are two families of hormones. The effects induced by interferons and growth factors are found to be directly opposite.