EICOSANOID RELEASE IN ALLERGEN-INDUCED BRONCHOCONSTRICTION IN DOGS - ITS RELATIONSHIP TO AIRWAYS HYPERREACTIVITY AND PULMONARY INFLAMMATION

In vitro studies have demonstrated the release of histamine, PGD(2), T XB(2), PGE(2), PGF(2 alpha), 6-keto-PGF(1 alpha) and the peptidoleukot rienes from sensitized lung. We have assessed the release of these med iators following antigen challenge in vivo. Antigen challenge of aller gic dogs resulted in an acute bronchoconstriction and an increase in b ronchial reactivity to histamine and an increase in neutrophil and eos inophil numbers recovered by bronchoalveolar lavage (BAL), 2 and 24 h later. The acute response was associated with histamine and PGD(2) rel ease but there was no increase in the levels of other eicosanoids in r ecovered BAL. Bronchial hyperreactivity and pulmonary inflammation, 2 and 24 h post-challenge was not associated with a concommitant (antige n specific) increase in BAL fluid eicosanoid levels. We conclude that although PGD(2) is released during the acute response to antigen the s ubsequent changes (hyperreactivity and inflammation) are not character ised by a maintained elevation in eicosanoid levels detectable by BAL.