Granulocyte and macrophage colony-stimulating factor from human placenta conditioned medium

Conditioned medium prepared from human placenta tissue stimulates in vitro colony formation by mouse and human marrow cells. At least two types of colony-stimulating activities are found and can be separated by isoelectrofocusing. The first type of colony-stimulating factor (CSF) shows heterogeneity on isoelectrofocusing with pI in the range of 3.6-4.7. It has been purified 10(5)-fold by hydroxylapatite chromatography, preparative isoelectrofocusing, gel filtration, polyacrylamide gel isoelectrofocusing, and electrophoresis to a specific activity of 7.5 X 10(7) units/mg. The purified CSF shows a single band on microgel electrophoresis and stimulates mostly mouse macrophage colony formation. It has a molecular weight of 41 000 as determined by gel filtration and is sensitive to proteolytic enzyme digestion and periodate oxidation. Treatment with neuraminidase is without effect on activity. It is stable at pH 5-10 and 60 degrees C for 30 min. The second type of CSF appears as a single activity peak on isoelectrofocusing with a pI of 5.7. The molecular weight is calculated to be 27 000 from gel filtration. It is very sensitive to trypsin and periodate but inert to neuraminidase or mercaptoethanol treatment. It is stable at neutral pH but labile at 60 degrees C for 30 min. The purified CSF stimulates predominantly granulocytic colony formation from human marrow cells.