Spermine down-regulates superoxide generation induced by fMet-Leu-Phe in electropermeabilized human neutrophils.

Effect of spermine, a naturally occurring polyamine, was investigated on superoxide generation in intact and electropermeabilized human neutrophils. Spermine suppressed N-formyl-methionyl leucyl phenylalanine (fMLP)-induced superoxide generation in permeabilized cells by reducing the rate and shortening the duration time. The inhibition was specific for spermine comparing with its precursor amines, spermidine and putrescine. The inhibition was not observed when cells were preincubated with spermine without permeabilization. Concanavalin A-induced superoxide generation was also down-regulated by spermine in permeabilized cells, but the activation induced by non receptor-mediated agonist (dioctanoylglycerol, phorbol myristate acetate, and arachidonate) was not affected by spermine. On the other hand, GTP-gamma-S-induced activation of superoxide generation was substantially suppressed by spermine. These results indicate that spermine inhibition occurs at a step prior to protein kinase C in signal transduction or in a pathway which is independent of the kinase.