Nanomolar arachidonic acid influences the respiratory burst in eosinophils and neutrophils induced by GTP-binding protein. A comparative study of the respiratory burst in bovine eosinophils and neutrophils

Aebischer, C.P.; Pasche, I.; Jörg, A.

European Journal of Biochemistry 218(2): 669-677

1993


ISSN/ISBN: 0014-2956
PMID: 8269958
DOI: 10.1111/j.1432-1033.1993.tb18421.x
Accession: 009075945

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Abstract
To investigate a possible role of phospholipase A-2 (PLA-2) in the respiratory burst in bovine eosinophilic and neutrophilic leukocytes dependent on GTP-binding protein (G-protein), we permeabilized these cells with Staphylococcus aureus alpha-toxin and induced NADPH oxidase activity with the non-hydrolysable GTP analogue GTP(S) or the aluminium tetrafluoro complex AIF-4-. Under same experimental conditions, cells responded with different onset times. The onset time for eosinophils was 50-200 s, for neutrophils it was only a few seconds. GTP(S) stimulated in neutrophils only 5% of the respiratory burst compared to eosinophils, whereas AIF-4--induced comparable responses (neutrophils 120% of eosinophils). GDP inhibited these responses with an IC-50 value of 2.4 mM. Arachidonic acid showed, with the exception of AIF-4- stimulated neutrophils, on both stimuli and cell types an enhancing effect (150%) that reached its maximum at 0.1-1 mu-M. The PLA-2 inhibitor 4-bromophenacylbromide reduced the GTP(S)- and AIF-4--induced response almost completely (10 mu-M) and the inhibition was not significantly different for eosinophils and neutrophils (IC-50 1-3 mu-M). If the respiratory burst was reduced with 4-bromophenacylbromide to 1 - 4% of the original value, 10% of the basal NADPH oxidase activity could be restored by addition of only 20-100 nM arachidonic acid. In addition, the PLA, activator adriamycin enhanced the response in a dose-dependent manner and in the same order as arachidonic acid did. The results presented above suggest that the respiratory burst may be regulated by different low-molecular-mass and/or heterotrimeric G-proteins and an active role for arachidonic acid or its metabolites in the activation and the maintenance of the direct G-protein-stimulated respiratory burst in bovine eosinophils and neutrophils.

Nanomolar arachidonic acid influences the respiratory burst in eosinophils and neutrophils induced by GTP-binding protein. A comparative study of the respiratory burst in bovine eosinophils and neutrophils