The effect of neutrophils, tumor necrosis factor, and granulocyte macrophage/colony stimulating factor on Babesia bovis and Babesia bigemina in culture.

Bovine neutrophils, human recombinant tumor necrosis factor-alpha (TNF), and bovine recombinant granulocyte macrophage/colony stimulating factor (GM/CSF) were added to microaerophilic cultures of Babesia bovis and Babesia bigemina to determine if those substances could inhibit growth. Incorporation of [3H]hypoxanthine by the Babesia spp. was utilized as an indirect measure of parasite growth. When neutrophils were added to cultures of B. bovis and B. bigemina, the highest percentage inhibition of growth was attained. There was no significant enhancement of neutrophil killing when TNF or GM/CSF or both were added to either Babesia spp. Addition of TNF or GM/CSF or both substances (without neutrophils) resulted in an increase in growth of B. bovis and B. bigemina. For B. bovis, the group that contained neutrophils only and the group that contained neutrophils and TNF resulted in significantly higher growth inhibitions than the treatment group which contained neutrophils and GM/CSF or the group that contained neutrophils, TNF, and GM/CSF. No significant differences in inhibition were observed for the same treatment groups between B. bovis and B. bigemina.