This experiment was performed to clarify the role of protein kinase C (PKC) delta in NADPH oxidase-dependent O(2-) production and actin polymerization followed by phagocytosis in neutrophils. Bovine neutrophils and human neutrophil-like differentiated HL-60 (dHL-60) cells were stimulated with serum-opsonized zymosan (OZ) and fMet-Leu-Phe (fMLP), respectively. Rottlerin, a specific inhibitor of PKCdelta, attenuated the production of O(2-) from NADPH oxidase in both neutrophils and dHL-60 cells. However, it did not inhibit the translocation of p47(phox) from the cytosol to the membrane in either type of cell or the phosphorylation of p47(phox) in dHL-60 cells. GF109203X (GFX), an inhibitor of cPKC, attenuated not only the production of O(2-) but also the translocation of p47(phox) in both cells. Furthermore, rottlerin significantly attenuated the ingestion of opsonized particles and the formation of F-actin in OZ-stimulated neutrophils, whereas, GFX did not affect those phagocytic processes. These results suggest that both PKCdelta and cPKC regulate NADPH oxidase through different pathways, but only PKCdelta regulates the phagocytic function in neutrophils.