Bronchial hyperresponsiveness to methacholine and adenosine monophosphate and the degree of atopy in children with allergic rhinitis

Background: Nonasthmatic patients with allergic rhinitis often have bronchial hypen-esponsiveness (BHR). Not only the presence but also the degree of atopy are important factors in BEAR of patients with asthma. BHR is commonly evaluated by bronchial challenges using direct or indirect stimuli. Objectives: To assess BHR to methacholine (direct) and to adenosine monophosphate (AMP) (indirect) in children with allergic rhinitis and to compare their relationships with the degree of atopy. Methods: Methacholine and AMP challenges were performed in 88 children with allergic rhinitis, and a provocative concentration causing a 20% decrease in forced expiratory volume in 1 second (PC20) was calculated for each challenge. The degree of atopy was measured using serum total IgE levels, number of positive skin prick test results, and atopic scores (sum of graded wheal size). Results: BHR to methacholine (PC20 <8 mg/mL) and to AMP (PC20 <200 mg/mL) was observed in 22 (25%) and 30 (34%) patients, respectively. No association was found between BHR to methacholine and any atopy parameter. In contrast, serum total IgE levels and atopic scores were higher in the group with BHR to AMP than in the group without BHR to AMP. Furthermore, a significant association was found between the degree of these 2 parameters and BHR to AMP (score for trend, P < .001 and P = .03, respectively). Conclusions: Both BHR to methacholine and BHR to AMP were detected in a significant proportion of children with allergic rhinitis. The degree of atopy seems to be an important factor in BHR to AMP but not in BHR to methacholine. Ann Allergy Asthma Immunol. 2011;106:36-41.