Modulatory effect of roxithromycin on human neutrophil function.

Neutrophils are thought to play a key role in tissue injury. We investigated the effect of roxithromycin, a 14-membered ring macrolide, on human neutrophil functions. The drug inhibited N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide (O2-) production and Ca2+ influx of human neutrophils. The inhibition was overcome by adding an inhibitor of cyclic AMP-dependent protein kinase (PKA), H-89. These results suggest that the drug affects O2- production and intracellular Ca2+ concentration of neutrophils via the action of PKA. Moreover, roxithromycin ameliorated endothelial cell injury induced by neutrophils, which may be, in part, due to the effect of the drug on neutrophils. Thus, roxithromycin may contribute to the treatment of diseases worsened by the excessive action of neutrophils.