Evaluation of Nasal Mucosal Permeability in Controls and House Dust Mite Allergic Rhinitis Patients

Inclusion Criteria: 1. Patients with an ARIA-based diagnosis of persistent moderate/severe AR (≥ 2 nasal symptoms suggestive of allergic rhinitis and positive skin prick tests to HDM (HAL Allergy, Leiden, The Netherlands), and with VAS score for total nasal symptoms of more than 5 2. Age \> 18 and \< 60 years. 3. Possibility to give reliable information and written informed consent 4. For AR group with nasal corticosteroid spray: Patients that use nasal corticosteroid spray for at least three weeks prior to the study, with a minimum application of two puffs per nostril once a day. Exclusion Criteria: 1. No common cold in the last 4 weeks 2. Patients on prolonged use of decongestive nose sprays, suffering from so-called rhinitis medicamentosa 3. A. For healthy controls and AR without use of nasal spray: Patients using other nasal or oral medication affecting nasal function, like nasal corticosteroids, anticholinergics, cromoglycates, leukotriene antagonists, ACE inhibitors less than 4 weeks before start of the study. B. For AR group with use of nasal corticosteroid spray: Patients using other nasal or oral medication affecting nasal function, like anticholinergics, cromoglycates, leukotriene antagonists, ACE inhibitors less than 4 weeks before start of the study. 4. Nasal endoscopic evidence of rhinosinusitis w/wo NP or structural abnormalities such as clinically relevant septal deviation (septum reaching concha inferior or lateral nasal wall) or septal perforation 5. Patients on immunotherapy (IT) for house dust mite (HDM) or with history of IT for HDM 6. Patient with a psychiatric, addictive, or any disorder of which the investigators feel that this may compromise the ability to give truly informed consent for participation in this study or provide reliable information on the questionnaire 7. Patients being enrolled in other clinical trials 8. Pregnancy or breastfeeding 9. Malignancies or severe comorbidity 10. Contra-indication for local anesthesia with cocaine 5% 11. Smoking 12. Use of anticoagulation medication Healthy controls will meet the same exclusion criteria, with additional inclusion criteria: 1. Absence of nasal symptoms 2. Negative history of respiratory allergy 3. Negative skin prick test (SPT) results