The effects of in vitro and in vivo treatment of bovine polymorphonuclear leukocytes with recombinant bovine interferon-γ on in vitro bovine polymorphonuclear leukocyte functions and the survival of Brucella abortus were determined. Activation of neutrophils in vitro with interferon-γ resulted in enhanced production of O2− and myelopeoroxidase-H2O2-halide activity by neutrophils in the presence of B. abortus. The improved iodination responses were correlated with an enhanced ability to perform iodination in the presence of 5′-guanosine monophosphate and adenine which have previously been shown to contribute to inhibition of neutrophil myeloperoxidase-H2O2-halide activity by B. abortus. The ability of opsonized B. abortus to survive in the presence of neutrophils activated in vitro or in vivo was partially decreased by ∼10% of control when compared to survival rates within control phagocytes. These results suggest that activation of neutrophils with recombinant interferon-γ partially enhances their oxidative metabolic responses, resulting in a slightly enhanced ability to kill virulent B. abortus.