Abstract
Summary
Biological activities associated with colony-stimulating factor (CSF) from human leukemic urine were found to be selectively retained on an affinity adsorbent of Con A-Sepharose. Elution of activity was achieved using a linear gradient of either α-methyl-D-mannopyranoside (αMM) or α-methyl-D-glucopyranoside (αMG), and resulted in significant increases in specific biological activity. Rechromatography of appropriate fractions indicated that retention of CSF activities was not artifactual. Pretreatment of the affinity matrix with αMM completely inhibited binding of CSF. Affinity chromatography of CSF on a Blue Dextran-Sepharose adsorbent was found to be an effective method for removing albumin, a major protein contaminant in urinary preparations. Treatment of CSF with neuraminidase had no effect on its in vitro activity; however, such treatment resulted in an increase in the isoelectric point of CSF from pH 3.5 to pH 4.7, as determined using both sucrose and polyacrylamide gel stabilized pH gradients. Relatively broad regions of biological activity were observed following isoelectric focusing of both neuraminidasetreated and untreated CSF, suggesting that activity was associated with a heterogeneous/polydisperse population of molecular species.
The authors thank E. S. Mingioli, M. Parker, D. LaVia, and B. Jambois for expert technical assistance. We are indebted to Dr. J. Mendicino for informing us about the properties of Blue Dextran-Sepharose. We also thank Dr. E. R. Stanley, who, following completion of the present studies, brought to our attention an earlier workshop report of related work, and, indirectly, a paper by Iscove et al. (34), who showed that colony-stimulating activity was retained on an affinity matrix similar to ours.
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