We studied the effects of recombinant dolphin tumor necrosis factor alpha (rdoTNFalpha) on the respiratory burst activity of dolphin neutrophils. rdoTNFalpha enhanced the luminol-dependent chemiluminescence response of dolphin neutrophils induced by concanavalin-A, opsonized zymosan, and heated plasma, but not that induced by phorbol myristate acetate. The TNF-associated priming activity was concentration- and preincubation time-dependent, and heat-instable. These data suggest that, as in human neutrophils, TNFalpha enhances the respiratory burst in dolphin neutrophils that follows short-term incubation with various receptor-mediated agonists.