C-reactive protein decreases protein phosphorylation in stimulated human neutrophils

Treatment of human neutrophils with C-reactive protein (CRP) causes a concentration-dependent in the extent of activation of superoxide production and of granule secretion, induced by phorbol-12-myristate-13-acetate (PMA) or N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLF). The same treatment also causes a significant reduction in the degree of PMA- and fMLF-stimulated phosphorylation of several cell proteins. These include the proteins of 43-47 kDa, whose extent of phosphorylation correlates with the activation of superoxide production and of secretion. Contrary to the effects exerted on protein phosphorylation, CRP does not affect the fMLF-elicited increase in neutrophil cytosolic Ca2+.