Abstract
The polyamines putrescine, spermidine and spermine, at concentrations of 10 μM, stimulated superoxide generation by human polymorphonuclear leukocytes induced by fMet-Leu-Phe in the presence of Ca 2+. This positive effect was not evident in the absence of Ca 2+ or when the polymorphonuclear leukocytes were stimulated by phorbol myristate acetate. Spermidine in the range of 10–100 μM showed a dose-dependent stimulatory effect on the superoxide generation induced by fMet-Leu-Phe, whilst at doses above 25 mM it produced an inhibitory effect. At this concentration, spermidine did not reduce the phorbol myristate acetate-neutrophil-induced O 2 −· generation, while an inhibitory effect by the polyamine was evident at concentrations above 50 mM. In addition, 100 μM spermidine increased the amount of superoxide generated and enhanced the ability of the chemotactic peptide to stimulate superoxide generation. The polyamines in the range of 10 μM-25 mM did not modify the activity of purified NADPH oxidase, nor the rate of reduction of cytochrome c as supported by the xanthine / xanthine oxidase reaction. These results indicate that physiological concentrations of polyamines can stimulate superoxide formation by polymorphonuclear leukocyte cells produced by the chemotactic peptide fMet-Leu-Phe, probably by increasing the availability of external calcium.
Published Version
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