REDUCED AIRWAY ABSORPTION IN SEASONAL ALLERGIC RHINITIS

The common notion that increased mucosal absorption characterizes alle rgic and inflamed airways is poorly supported by physiologic in vivo d ata. We have now examined whether the airway mucosa of patients with s easonal allergic rhinitis develop a change in absorption during their active disease period. Twelve patients with birch pollen rhinitis were examined twice, prior to and late into a Swedish birch pollen season, Ten healthy subjects were examined once, A nasal pool device was used to fill the unilateral nasal cavity with fluid containing 1-deamino-8 -D-arginine vasopressin (desmopressin, 20 mu g/ml) as absorption trace r. The peptide tracer solution was removed after 15 min, and absorptio n was determined by analysis of the peptide in the 24-h urine sample. Nasal absorption did not differ between healthy subjects and symptom-f ree patients outside the season. After 3 wk of symptom-producing seaso nal allergic rhinitis, absorption of the peptide across the nasal muco sa was less (p < 0.05) than outside the season. These data indicate th at hyperresponsiveness and disease progression in seasonal allergic rh initis are not due to a compromise of the mucosal barrier that would p ermit increased absorption of mucosally deposited solutes, The reduced absorption may in part reflect the ability of the airway epithelium i n vivo to maintain and potentially improve its barrier function by eff icient epithelial restitution processes.