Fluoride prevents degranulation of the azurophilic and specific granules in electropermeabilized neutrophils.

The effect of AlF4- on the degranulation process in human neutrophils was investigated. In intact neutrophils, AlF4- induced degranulation, whereas in electropermeabilized neutrophils AlF4- did not stimulate degranulation. In electropermeabilized neutrophils, fluoride ions proved to be inhibitory for the degranulation induced by addition of Ca2+ and/or GTP-gamma-S. Another phosphatase inhibitor, okadaic acid, inhibited degranulation induced by Ca2+ or by GTP-gamma-S but not degranulation induced by the combination of Ca2+ plus GTP-gamma-S. It is concluded that under suboptimal conditions of stimulation with Ca2+ or GTP-gamma-S, protein dephosphorylation plays an important role in the degranulation response in human neutrophils.