Allergen-Induced Bronchoconstriction in Asthmatic Children (1)
Platelet-activating factor (PAF-acether, l-0-alkyl-2-0-acetyl-sn-glyceryl-3-phosphorylcholine) is a potent phospholipid mediator involved in a wide variety of diseases. Animal experiments have demonstrated that PAF can produce bronchoconstriction,- increase vascular permeability, induce airway hyperreactivity, recruit inflammatory cells, especially eosinophils, into the lungs, and attenuate the airways allergic response.
Several lines of evidence from recent studies strongly suggest that PAF may also be an important mediator of the inflammatory events associated with asthma in humans: (1) plasma platelet factor 4 was increased during antigen-induced airway reaction in asthmatic subjects; (2) platelet products were detected in the lavage fluid of asthmatic subjects; (3) PAF was detected in sputum of asthmatic subjects; (4) intratracheal administration of PAF caused bron-chospasm in decerebrated humans; and (5) most importantly, aerosolized PAF was capable of inducing bronchoconstriction and bronchial hyperresponsiveness in both normal subjects and asthmatic patients. Therefore, it has been proposed that PAF antagonists can be of clinical importance in the prevention and treatment of bronchial asthma.