[Human serum colony-stimulating factor in mouse bone marrow culture].

Activity of CSF was measured in human serum after chromatography on Sephadex G-200. Agar culture of bone marrow cells was done in Petri dishes with agar in Eagle'a medium containing fetal calf serum and antibiotics. This agar-medium containing mouse bone marrow cells, was allowed to gel and the dishes were incubated at 37 degrees C in a fully humidified atmosphere of 10% CO2 in air. Our data indicate that chromatography procedure allows to get CSF free from its inhibitors. All activity was localized in one peak, in the region of low molecular weight proteins.