A role for paf-acether (platelet-activating factor) in bronchial hyperreactivity?

Paf-acether (platelet-activating factor, 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a potent mediator of inflammation and allergy, synthesized by various cell types. It is noteworthy that IgE-sensitized alveolar macrophages are capable of releasing this mediator which, in turn, induces a platelet-dependent, cyclooxygenase-independent acute bronchoconstriction in the guinea pig, monkey, and man. Indirect evidence suggests that this mediator may also play a role in human asthma as an inducer of bronchial hyperreactivity, but clear definition of its importance in any disease must await study of the effects of specific, selective antagonists.