Bronchial rings from non-atopic humans were passively sensitized with serum from allergic subjects. Allergen challenge reduced significantly the relaxant effect of salbutamol on carbachol-induced contractions, suggesting ß₂-adrenoceptor pathway dysfunction. Incubation of challenged rings for 3 h with beclomethasone dipropionate (BDP) 3x10^-6M restored the relaxant effect, suggesting reversal of ß₂-adrenoceptor pathway dysfunction. Incubation with the G_s-protein stimulating cholera toxin (CTX) attenuated contractile responses to carbachol significantly less in challenged than in unchallenged rings. Treatment of challenged rings with BDP resulted in an inhibitory effect of CTX that was similar to that in unchallenged rings. G_s-protein expression was not significantly altered by BDP, suggesting that the activity of G_s-protein was increased. Relaxation of challenged rings by forskolin was not significantly affected by BDP, suggesting the ß₂-adrenoceptor pathway dysfunction to be proximal to the adenylyl cyclase. In conclusion, short term (3 h) treatment with BDP after allergen challenge ablatedß₂-adrenoceptor pathway dysfunction by increasing the activity of the G_s-protein in human isolated bronchi.