Sensitization to aeroallergens and airway hyperresponsiveness at 7 years of age.

STUDY OBJECTIVES: To investigate the relationship between current and early life factors and airway responsiveness to inhaled methacholine in children with a median age of 7.0 years. PARTICIPANTS: Study subjects were a subset of a prospective birth cohort of children in the Boston area at high risk for atopy. METHODS: One hundred thirty-one children underwent both skin-prick testing to a panel of aeroallergens and a methacholine challenge test between 6.5 years and 8.8 years of age. Telephone questionnaires were performed at set intervals, and home dust samples were collected in the first year of life. RESULTS: Of the 131 participating children, 51% (67 patients) had at least one positive skin-prick test response and 28% (37 patients) had airway hyperresponsiveness (AHR) [provocative concentration of methacholine causing a 20% fall in FEV(1) of < 4 mg/mL]. After adjusting for relevant covariates, AHR was strongly associated with sensitization to at least four aeroallergens (odds ratio [OR], 13.41; 95% confidence interval [CI], 3.03 to 59.42). In separate adjusted models, sensitization to cat (OR, 14.73; 95% CI, 3.64 to 59.55), dust mite (OR, 5.13; 95% CI, 1.94 to 13.56), cockroach (OR, 4.00; 95% CI, 1.19 to 13.50), and ragweed (OR, 10.08; 95% CI, 2.31 to 44.10) were significant predictors of AHR. However, no relationship was found with early life exposure to perennial aeroallergens or other perinatal and first-year-of-life factors. CONCLUSIONS: Among young children at risk for atopy, sensitization to specific aeroallergens, but not early life exposures, is associated with increased airway responsiveness.

Clinical efficacy of microencapsulated timothy grass pollen extract in grass-allergic individuals.

BACKGROUND: Conventional allergen immunotherapy is clinically effective in reducing the symptoms of allergic rhinitis and asthma. It differs from other pharmacotherapies in that it can induce long-term clinical remission of these diseases. However, it requires years of treatment and is associated with serious allergic reactions. OBJECTIVE: To evaluate the safety, clinical efficacy, and immunologic mechanisms of immunotherapy with an oral, microencapsulated form of timothy grass allergen. METHODS: In this double-blind, placebo-controlled study, 24 patients aged 19 to 55 years with grass pollen allergy were randomized to receive either microencapsulated timothy grass pollen extract or placebo once a day for 10 weeks. The dose of study drug was doubled weekly. Safety was evaluated through weekly visits, daily symptom diaries, and routine laboratory tests. Efficacy was evaluated by comparing medication use and symptoms scores during peak grass pollen season before and after treatment. Allergen-specific T-cell responses, cytokine production, and IgG, IgE, and skin reactivity were measured to evaluate immunologic mechanisms. RESULTS: Eleven of 12 patients in the active treatment group had a decrease in the combined medication and symptom score, but only 4 of 10 patients in the placebo group had a decrease in scores. The proliferative response to timothy grass was reduced by at least 30% in 9 of the 12 grass-treated patients, but only 3 of 11 placebo patients had a proliferative response reduction. Timothy grass-induced interleukin-5 messenger RNA was reduced in the active group, but not in the placebo group. There were no significant changes in either group in IgG, IgE, and skin reactivity. CONCLUSIONS: Oral immunotherapy with microencapsulated allergen induces a form of immunologic tolerance to the allergen and is a safe, efficient, and effective method of allergen immunotherapy.