PURINE DERIVATIVES IN THE STUDY OF ALLERGIC INFLAMMATION IN RESPIRATORY-DISEASES

Adenosine, a naturally occurring purine nucleoside, elicits dose-relat ed bronchoconstriction in asthmatic subjects when administered by inha lation and it is recovered in increased amounts from the bronchial lav age fluid of subjects with active asthma when compared to normal contr ols. Although the mechanism by which adenosine mediates bronchoconstri ction in asthmatic subjects is not clear, recent data indicate an impo rtant role for mast cell mediator release. We have recently shown that local airway challenge with adenosine in subjects with asthma and rhi nitis provokes an increase in the levels of PGD2, histamine and trypta se. However, airway responsiveness and atopic status are the most impo rtant determinants of adenosine-induced responses, regardless of any i ncreases in mast cell mediators in airway fluids. New discoveries sugg est that the airway response to adenosine may be an index of mast cell priming and therefore may provide a useful tool to further explore th e inflammatory processes in allergic asthma and rhinitis. Therefore ad enosine provocation may gain increasing acceptance as an additional me asure of disease activity in asthma and rhinitis.