Because an endogenous phospholipase C (PLC) participates in neutrophil activation and because many bacterial pathogens produce PLCs, these studies examined the effect of PLC from Bacillus cereus on the release of the granule enzyme lysozyme from human neutrophils. Bacillus cereus PLC caused dose-dependent lysozyme release, and combined stimulation of neutrophils with PLC and fluoride led to increased secretion. Stimulation of neutrophil degranulation is a potential contributing factor for tissue damage in infections caused by PLC-producing organisms.