Preparative purification of human placental colony-stimulating factors

For preparative purification of colony-stimulating factors (CSF) from human placental conditioned medium, cation exchange chromatography, gel filtration, and isoelectric focusing were combined. The individual fractions were tested using the growth in agar of cryopreserved human bone marrow (dose-response curves). Furthermore, the active preparations were characterized by analytical isoelectric focusing. Two fractions with highly enriched biological activity were isolated. They have the isoelectric points 5.4 and 5.6, respectively. Their specific activity exceeds that of the crude material by a factor of 60. Like crude material, they induce predominantly granulocytic colonies. The biochemical heterogeneity of biological activity in placental supernatants is discussed.