Abstract
Summary
Limulus lysate assays showed that several samples of purified L-cell CSF were markedly contaminated with endotoxin. Several pools of material contained 1 to 10 μg/ml of this bacterial lipopoly-saccharide. Ultracentrifugation in sucrose density gradients led to a 95% separation of CSF and endotoxin activities. In four studies, endotoxin content of the CSF preparations was reduced to levels varying from 0.05 to 0.0001 μg/ml.
In vivo studies with known quantities of E. coli endotoxin were conducted in mice. Acute and repeated injections of 0.1 μg of endotoxin led to increased serum CSF activity and increased number of splenic CFU-C and CFU-E. In contrast, similar injections of 0.01 μg of endotoxin produced virtually no effect on these parameters of hemopoiesis. Thus, the removal of endotoxin from CSF as outlined herein will permit in vivo studies of the effects of CSF on hemopoiesis, without concern for the complicating effects of endotoxin.
The authors gratefully appreciate the excellent technical assistance of Florence Boegel, Lea Einsporn, and Francine C. Levin.
Get full access to this article
View all access options for this article.