Arachidonic acid triggers an oxidative burst in leukocytes
AUTOR(ES)
Pompeia, C., Cury-Boaventura, M.F., Curi, R.
FONTE
Brazilian Journal of Medical and Biological Research
DATA DE PUBLICAÇÃO
2003-11
RESUMO
The change in cellular reducing potential, most likely reflecting an oxidative burst, was investigated in arachidonic acid- (AA) stimulated leukocytes. The cells studied included the human leukemia cell lines HL-60 (undifferentiated and differentiated into macrophage-like and polymorphonuclear-like cells), Jurkat and Raji, and thymocytes and macrophages from rat primary cultures. The oxidative burst was assessed by nitroblue tetrazolium reduction. AA increased the oxidative burst until an optimum AA concentration was reached and the burst decreased thereafter. In the leukemia cell lines, optimum concentration ranged from 200 to 400 µM (up to 16-fold), whereas in rat cells it varied from 10 to 20 µM. Initial rates of superoxide generation were high, decreasing steadily and ceasing about 2 h post-treatment. The continuous presence of AA was not needed to stimulate superoxide generation. It seems that the NADPH oxidase system participates in AA-stimulated superoxide production in these cells since the oxidative burst was stimulated by NADPH and inhibited by N-ethylmaleimide, diphenyleneiodonium and superoxide dismutase. Some of the effects of AA on the oxidative burst may be due to its detergent action. There apparently was no contribution of other superoxide-generating systems such as xanthine-xanthine oxidase, cytochromes P-450 and mitochondrial electron transport chain, as assessed by the use of inhibitors. Eicosanoids and nitric oxide also do not seem to interfere with the AA-stimulated oxidative burst since there was no systematic effect of cyclooxygenase, lipoxygenase or nitric oxide synthase inhibitors, but lipid peroxides may play a role, as indicated by the inhibition of nitroblue tetrazolium reduction promoted by tocopherol.
Documentos Relacionados
- Arachidonic acid metabolism in polymorphonuclear leukocytes: Effects of ionophore A23187*
- Enhanced oxidative burst in immunologically activated but not elicited polymorphonuclear leukocytes correlates with fungicidal activity.
- Enhanced Oxidative Burst in Immunologically Activated but Not Elicited Polymorphonuclear Leukocytes Correlates with Fungicidal Activity
- Arachidonic acid metabolism in polymorphonuclear leukocytes from patients with chronic granulomatous disease.
- Pneumocystis carinii induces an oxidative burst in alveolar macrophages.