title: Effective allergen avoidance at high altitude reduces allergen-induced bronchial hyperresponsiveness.
abstract: We studied the effects of reduced allergen exposure on bronchial hypereactivity (BHR) in two groups of asthmatic children allergic to house dust mites (HDM) living at high altitude for 9 continuous mo. In the first group the serum levels of total and HDM-specific IgE showed significant decreases after 3 mo (p < 0.001 and p < 0.02, respectively) and after 9 mo (p < 0.001). Three months after returning home the total IgE levels had increased significantly (p < 0.001). The mean percentage fall in peak expiratory flow after exercise testing improved after 3 and 9 mo (p < 0.05), but it had deteriorated after 3 mo at home (p < 0.01). The methacholine PD20-FEV1 increased after 3 mo (p = 0.001) and further after 9 mo (p < 0.001), with a decrease after the 3-mo period at sea level (p = 0.01). In the second cohort there was a significant increase in HDM PD20-FEV1 after 6 and 9 mo (p < 0.001), with a slight decrease of magnitude of the allergen-induced late reaction. Histamine PD20-FEV1 significantly increased after 6 and 9 mo at high altitude, particularly in the challenges performed after the HDM bronchial provocation (p < 0.01). Our data demonstrate that allergen avoidance in asthmatic children not only decreases nonspecific BHR but also decreases allergen sensitivity, late allergen-induced bronchial reactions, and enhancement of BHR by allergen challenge.
authors.affiliation: Clinica Pediatrica, University of Verona, Italy.
authors.forename: D G
authors.initials: DG
authors.lastname: Peroni
authors.forename: A L
authors.initials: AL
authors.lastname: Boner
authors.forename: G
authors.initials: G
authors.lastname: Vallone
authors.forename: I
authors.initials: I
authors.lastname: Antolini
authors.forename: J O
authors.initials: JO
authors.lastname: Warner
mesh_terms: D000485:Allergens / Q000276:immunology; D000531:Altitude; D000704:Analysis of Variance; D000818:Animals; D001249:Asthma / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control*; D001985:Bronchial Provocation Tests; D002648:Child; D015331:Cohort Studies; D004391:Dust; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005080:Exercise Test; D005541:Forced Expiratory Volume; D006632:Histamine; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000276:immunology / Q000517:prevention & control*; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D016210:Methacholine Chloride; D008925:Mites; D010366:Peak Expiratory Flow Rate; D011322:Primary Prevention; D012008:Recurrence; D012111:Residence Characteristics; D012112:Residential Facilities; D012621:Seasons; D012882:Skin Tests; D013997:Time Factors
chemical_list: D000485:Allergens; D004391:Dust; D016210:Methacholine Chloride; D007073:Immunoglobulin E; D006632:Histamine