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Evidence for platelet-activating factor secretion during immune activation in dogs
N M Munoz1, N P Stimler-Gerard, M M Mack
1Department of Medicine, University of Chicago, Illinois 60637.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1989
Summary
Platelet-activating factor (PAF) contributes to bronchoconstriction during allergic reactions. Ascaris antigen exposure diminishes the response to PAF, suggesting its role in acute allergic airway responses.
Area of Science:
- Immunology
- Pulmonology
- Pharmacology
Background:
- Platelet-activating factor (PAF) is implicated in allergic airway inflammation.
- The role of PAF in acute bronchoconstriction during immune challenges requires further elucidation.
Purpose of the Study:
- To investigate the physiological significance of PAF in acute bronchoconstriction.
- To examine the effect of Ascaris suum antigen on the tachyphylactic response to PAF in allergic dogs.
Main Methods:
- In vivo study using 15 natively allergic mongrel dogs.
- Measurement of active bronchial tension isometrically.
- Quantification of mediator secretion via arteriovenous difference in plasma concentration.
Main Results:
- PAF caused dose-related bronchial contraction, paralleling serotonin release but not histamine.
- PAF response exhibited significant tachyphylaxis.
- Ascaris antigen challenge led to diminished PAF responsiveness and substantial histamine release.
Conclusions:
- Data suggest endogenous PAF plays a physiological role in bronchial smooth muscle contraction during acute Ascaris-induced immune responses.
- PAF tachyphylaxis is observed following antigen challenge in allergic dogs.
