Biochemical properties of bovine granulocytes.

Granulocyte fractions, containing an average of about 92% neutrophils, were isolated from bovine blood. The electron microscope observation of these fractions showed that neutrophil granules have different shapes, but are all highly and homogeneously electron-dense. With respect to the granulocytes of human blood, bovine cells appear to have a lower content of azurophil enzymes and virtually lack lysozyme. Lysates of bovine granulocytes efficiently kill both E. coli (at pH 6.0 and 7.4) and S. aureus (mainly at pH 7.4). When exposed to opsonized B. mycoides, intact bovine granulocytes exhibit a marked enhancement in oxygen consumption, generation of O2- and H2O2, and glucose oxidation through the hexose monophosphate pathway. About 15% of the total oxygen reduced is recovered extracellularly as O2-. Hydrogen peroxide generated by phagocytizing cells is only partially utilized in reactions catalyzed by catalase and myeloperoxidase, and appears to mainly enter the glutathione cycle.