Platelets enhance Fc(gamma) receptor-mediated phagocytosis and respiratory burst in neutrophils: the role of purinergic modulation and actin polymerization.
J Leukoc Biol
; 60(1): 58-68, 1996 Jul.
Article
em En
| MEDLINE
| ID: mdl-8699124
ABSTRACT
The interaction of platelets with neutrophil granulocytes is considered to play an important role in the inflammatory process, and the present study was focused on platelet-induced modulation of Fcgamma receptor-mediated functions in neutrophils. We found that phagocytosis and the respiratory burst (measured as luminol-enhanced chemiluminescence), triggered in neutrophils by immunoglobulin G (IgG)-opsonized yeast particles, were potentiated by platelets and that maximal enhancement was achieved at a physiological neutrophil/platelet ratio of about 150 to 1100. Platelets both increased the intra- and extracellular generation of oxygen radicals as well as the release of myeloperoxidase from stimulated neutrophils. The presence of platelets also induced a cortical actin polymerization in neutrophils, which might explain the increased phagocytic capacity. Platelets appear to affect neutrophil function in a contact-independent manner that most likely involves ATP, indicated by the following (1) platelet supernatants, but not fixed platelets, affected neutrophil function in the same way as viable platelets; (2) platelets raised the extracellular ATP level four- to fivefold; (3) exogenous ATP mimicked the effects of platelets on actin polymerization, phagocytosis, and the respiratory burst in neutrophils; (4) hydrolysis of extracellular ATP with apyrase or blocking of ATP receptors with suramin reversed the platelet-induced enhancement of neutrophil function. An increased accumulation of extracellular adenosine, induced by inhibiting endogenous adenosine deaminase or adding exogenous adenosine, reversed the effects of platelets. The platelet-induced potentiation of the respiratory burst was inhibited by the tyrosine kinase inhibitor genistein, suggesting that tyrosine phosphorylation is involved. However, platelets did not significantly affect the Fcgamma receptor-triggered calcium response in neutrophils. In conclusion, we show that platelets, through an ATP-dependent mechanism, potentiate IgG-mediated ingestion and production of oxygen metabolites in neutrophils.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fagocitose
/
Plaquetas
/
Trifosfato de Adenosina
/
Explosão Respiratória
/
Receptores de IgG
/
Neutrófilos
Limite:
Humans
Idioma:
En
Revista:
J Leukoc Biol
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Suécia