REGULATION OF NEUTROPHIL RESPIRATORY BURST BY PROTEIN PHOSPHATASES

Activation of human neutrophils involves a series of biochemical event s which have been linked to the phosphorylation of specific proteins. Okadaic acid is an inhibitor of protein phosphatases 1 and 2A, and inh ibits dephosphorylation of proteins in numerous cells. When human neut rophils were incubated with Okadaic acid prior to the stimulation with fMet-Leu-Phe (fMLP), an enhancement of superoxide anion release was s een. This enhancement was a result of a prolonged initial phase of sup eroxide release with a delay in the termination of the burst. In contr ast, superoxide release in response to phorbol myristate acetate was i nhibited. Okadaic acid had no effect on fMLP induced degranulation. Th ese results indicate that dephosphorylation events, which are inhibite d by Okadaic acid, have a role in regulating the rate and extent of th e human neutrophils respiratory burst.