Protein kinase C-beta contributes to NADPH oxidase activation in neutrophils

We have analysed the involvement of the beta isotype of the protein kinase C(PKC) family in the activation of NADPH oxidase in primary neutrophils. Us ing immunofluorescence and cell fractionation, PKC-beta is shown to be recr uited to the plasma membrane upon stimulation with phorbol ester and to the phagosomal membrane upon phagocytosis of IgG-coated particles (Fc gamma-re ceptor stimulus). The time course of recruitment is similar to that of NADP H oxidase activation by these stimuli. The PKC-beta specific inhibitor 3791 96 inhibits the response to PMA as well as to IgG-coated bacteria. Partial inhibition occurs between 10 and 100 nM of inhibitor, the concentration at which PKC-beta, but not other PKC isotypes, is targeted. Neutrophils isolat ed from a mouse that lacks PKC-beta also showed an inhibition of NADPH oxid ase activation by PMA and IgG-coated particles. The level of inhibition is comparable to that achieved with 379196 in human neutrophils. Thus the PKC- beta isotype mediates activation of NADPH oxidase by PMA and by stimulation of Fc gamma receptors in neutrophils.