Inhibition of leukopoiesis by sera from Trypanosoma congolense infected calves: partial characterization of the inhibitory factor.

Sera collected from calves infected with Trypanosoma congolense inhibited bovine granulocyte/macrophage colony formation in vitro, but not erythroid colony formation. The inhibitor was found to be TCA precipitable in nature and on Sephadex G-200 chromatography, it was found to elute with the second major peak. Sonicated T. brucei, T. congolense, and T. theileri added directly into the cultures had no effect on granulocyte/macrophage colony formation, but induced significant enhancement of erythroid colony formation.