PARTIAL-PURIFICATION AND CHARACTERIZATION OF HUMAN MEGAKARYOCYTE COLONY-STIMULATING FACTOR (MEG-CSF)

Megakaryocyte colony‐stimulating factor (Meg‐CSF) in urinary extracts from patients with aplastic anemia was partially characterized and purified. Using Meg‐CSF‐enriched fractions, we established that the moiety has the following characteristics: 1) portions of the molecules having Meg‐CSF activity have sialic acid, probably with a biantennary structure, and β‐galactose residues as the terminal and penultimate sugars; 2) disulfide residues are an essential chemical group of the molecule and are located on its surface; and 3) Meg‐CSF activity is stable in n‐propanol, but not in acetonitrile with trifluoroacetic acid. Partial purification of Meg‐CSF by a four‐step procedure of ethanol precipitation, CM Affi‐Gel Blue chromatography, wheat germ agglutinin‐sepharose chromatography, and high‐resolution hydroxyapatite chromatography, yielded a concentrate with a 430‐ to 630‐fold increase in specific activity. The partially purified Meg‐CSF fractions stimulated both human and murine megakaryocytopoiesis in vitro (CFU‐meg). When analyzed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis under nonreduced conditions, Meg‐CSF activity was recovered in the 29–34 kDa molecular weight fractions. We have also shown that Meg‐CSF, purified from the urine of aplastic anemia patients, stimulated murine megakaryocytopoiesis and platelet production in vivo. Final purification of human urinary Meg‐CSF is currently in progress. Copyright © 1990 AlphaMed Press