Comparative responses to nasal allergen challenge in allergic rhinitic subjects with or without asthma
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BACKGROUND: Nasal allergen challenge (NAC) is useful to study the pathophysiology of rhinitis, and multiple challenges may more adequately approximate natural exposure. OBJECTIVE: To determine the effect of 4 consecutive daily NAC, on clinical and inflammatory parameters in rhinitics with or without asthma. METHODS: Rhinitic subjects were recruited: 19 with mild asthma and 13 without asthma. Subjects underwent a control challenge (normal saline) followed by 4 consecutive daily NAC. Allergen challenge consisted of spraying the chosen allergen extract into each nostril until a positive nasal response occurred. Symptoms were recorded on a Likert scale, and oral peak expiratory and nasal peak inspiratory flows allowed assessment of a nasal blockage index (NBI), for a period of 7 hours. Induced sputum and nasal lavage were performed on control day and after 1 and 4 days of NAC. RESULTS: Compared with the control day, there was a significant increase in symptom scores and NBI 10 minutes after each last daily NAC in both groups (p < 0.05). Symptom scores and NBI were similar for the 2 groups, except for nasal obstruction and rhinorrhea, which were more marked in subjects with asthma and rhinitis, respectively. Nasal lavage eosinophils were increased after 4 days of challenges in both groups, but there was no change in sputum eosinophils. No cumulative effect or any late response were observed in any of the groups over the challenge period. CONCLUSION: Multiple NAC may be a useful tool to study the pathophysiology of allergic rhinitis or its relationships with asthma. TRIAL REGISTRATION: ClinicalTrials.gov NCT01286129.
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