ALLERGEN-INDUCED INFLAMMATION IN THE NOSE - A COMPARISON OF ACUTE ANDREPEATED LOW-DOSE ALLERGEN EXPOSURE

To investigate allergic rhinitis induced by two experimental provocati on models, we compared local inflammation with markers of eosinophil a ctivity in peripheral blood. Patients with strictly seasonal allergic rhinitis were selected and investigated outside the pollen season. An acute challenge with increasing doses of allergen every 15 min until s ymptoms occurred was performed in nine patients. Nasal lavage and bloo d samples were taken before and 4 and 24 h after challenge. After a 6- week washout period, 10 patients were submitted to 7 days of repeated low allergen exposures. One small dose (approximate to 1/100 of the ac ute dose) was given each day. Blood and lavage samples were taken prio r to and after the period. As control four patients were challenged wi th diluent only. The acute challenge resulted in sneezing and nasal di scharge and blockage and was accompanied by a rise in histamine and eo sinophil cationic protein (ECP) in lavage fluid after 4 h and continui ng after 24 h, when there also was a rise in the number of eosinophils and ECP in peripheral blood. The repeated low-dose exposures caused v ery few symptoms but produced increased ECP in the lavage fluid and a trend toward increased histamine concentration. There were no changes in ECP, intracellular EG2 binding, or number of eosinophils in the blo od. No changes were seen in the control group. Our findings show that changes in eosinophil mediator release in nasal lavage can be seen aft er very low, but repeated, allergen exposures despite no, or minimal, clinical symptoms. (C) Munksgaard 1996.