Effects of specific immunotherapy in allergic rhinitic individuals with bronchial hyperresponsiveness

Allergic rhinitis can be associated with bronchial hyperresponsiveness (BHR ), and carries an increased risk for the development of asthma. The aim of this study was to evaluate the ability of specific Immunotherapy (SIT) to r educe the progression of allergic rhinitis to asthma and prevent the associ ated increase in BHR. Forty-four subjects monosensitized to Dermatophagoide s pteronyssinus, with perennial rhinitis and BHR to methacholine, were rand omly assigned to receive SIT or placebo in a double-blind study conducted o ver a period of 2 yr. After 1 yr of treatment, a 2.88-fold increase in the provocative dose of methacholine producing a 20% decrease in FEV1 (PD20FEV1 ) was recorded in the SIT-treated group (95% confidence interval [CI]: 3.98 - to 2.09-fold; p < 0.001), with a further increase to fourfold at the end of Year 2 (95% CI: 2.9- to 5.7-fold; p < 0.001). At the end of the study, t he methacholine PD20FEV1 was within the normal range in 50% of treated subj ects (p < 0.0001), and was significantly higher in this group than in the g roup receiving placebo (p < 0.0001). In contrast, no changes in methacholin e PD20FEV1 were found in the placebo group throughout the study. Although 9 % of subjects given placebo developed asthma, none of those treated with SI T did. This study suggests that SIT, when administered to carefully selecte d, monosensitized patients with perennial allergic rhinitis, reduces airway responsiveness in subjects with rhinitis, and may be an appropriate prophy lactic treatment for rhinitic patients with hyperreactive airways.