Colony-Stimulating and Inhibiting Factors in Sera from Normal and Endotoxin-Treated CF 1 Mice 1

Abstract

Summary

Sera from normal and endotoxintreated CF₁ mice were fractionated by Sephadex chromatography. CSF activity was demonstrated in the prealbumin region in serum obtained from mice that had previously received endotoxin. Identical fractions from mouse embryo conditioned medium also displayed CSF activity. Normal serum had very low or no detectable CSF levels. An inhibitor was demonstrable in the high molecular weight fractions from both normal and endotoxin serums. Its effect is decreased by utilizing a double-layer technique. These results suggest that there is an increase in CSF levels after endotoxin administration rather than a decrease of serum inhibitory factors. Furthermore, the increase in CSF detected in sera after administration of endotoxin does not depend on the presence of endotoxin in such sera.