A macrophage factor that stimulates the proliferation of vascular endothelial cells

Sarcoid macrophage-epithelioid cells have been shown to release a growth factor that stimulates the proliferation of vascular endothelial cells in vitro. In the presence of this factor, cultured endothelial cells can proliferate in a serum-free medium. Gel-chromatography on Sephadex G-75 revealed a single peak of activity on endothelial cells. The molecular weight was estimated at 7,000-10,000. The activity was heat-labile and trypsin-sensitive, and did not adhere to heparin-Sepharose.