Colony stimulating activity in sera of erythroleukemic mice (RLV-A)

RLV-A serum activity was measured by the agar colony assay to determine the effect of this erythroid dyscrasia on the granulopoietic humoral regulator, colony stimulating factor (CSF). In general, the sera of early, midstage and terminal animals not given endotoxin had high cluster forming properties compared to normal sera. The sera of early, midstage, and terminal mice treated with endotoxin had only a fraction of the colony forming ability of serum obtained from normal endotoxin-treated mice (EMS) with the earliest stages of the disease showing least activity followed by a rise in activity paralleling normal EMS, as the disease progressed. Sera from RLV-A endotoxin treated mice retained ability to stimulate cluster growth especially when compared to the slight activity displayed by normal endotoxin treated mouse sera.