SHORT COMMUNICATIONS: Interaction of Mouse Interferon and Platelet-Derived Growth Factor During Multiplication of BALB/c 3T3 Cells

Mouse fibroblast-drived interferon (MuIFN) at concentrations of 0.1-0.001 U/ml enhanced the multiplication of BALB/c 3T3 cells. Experiments with the cells cultured in 5% platelet poor plasma serum (PPPS) medium in which the cells not multiply without platelet derived growth factor (PDGF), suggested that there is a positive cooperativity between small amounts of MuIFN and submitogenic doses of PDGF.

The growth-promoting activity of 10,000-1,000 U/ml detected in the partially purified MuIFN from C₂₄₃ cells assayed in 5% PPPS medium was probably the result of the contamination of MuIFN preparations with a PDGF-like growth factor.