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Stimulation of degranulation from human eosinophils by platelet-activating factor
1Department of Thoracic Medicine, National Heart and Lung Institute, London, United Kingdom.
Journal of Immunology (Baltimore, Md. : 1950)
|May 15, 1989
Summary
Platelet-activating factor (PAF) activates human eosinophils, triggering the release of granule enzymes and superoxide anions. This PAF-induced eosinophil activation is relevant to allergic inflammation and bronchial asthma.
Area of Science:
- Immunology
- Cell Biology
- Allergy Research
Background:
- Platelet-activating factor (PAF) is a potent mediator implicated in allergic inflammation and bronchial asthma.
- Eosinophils play a key role in the pathogenesis of these conditions, potentially through interactions with PAF.
Purpose of the Study:
- To investigate the effects of PAF on the activation of purified human eosinophils.
- To measure PAF-induced degranulation and oxidative metabolism in eosinophils.
Main Methods:
- Human eosinophils were purified and exposed to varying concentrations of PAF.
- Degranulation was assessed by measuring the release of specific granule enzymes (e.g., eosinophil peroxidase, beta-glucuronidase).
- Oxidative metabolism was evaluated by quantifying superoxide anion production. PAF-antagonist WEB 2086 was used to assess competitive antagonism.
Main Results:
- PAF induced rapid, calcium-dependent degranulation of eosinophils at low nanomolar concentrations (ED50 ~1.5 nM).
- PAF triggered superoxide anion generation at higher micromolar concentrations (ED50 ~8.4 microM).
- Both effects were competitively inhibited by the PAF-antagonist WEB 2086.
Conclusions:
- PAF is a potent activator of human eosinophils, inducing both degranulation and superoxide anion production.
- These findings highlight the pathophysiologic relevance of PAF-eosinophil interactions in conditions like bronchial asthma.