Immunotherapy by inhalation of allergen in powder in house dust allergic asthma--a double-blind study.

The authors report the analysis of clinical and immunological parameters during local immunotherapy (LI) by inhalation of an extract in powder in patients with allergic asthma due to D. pteronyssinus (DP). The study was double-blind and lasted 24 months. Twenty-four patients were randomly assigned on a double-blind basis to receive by inhalation increasing doses of a micronized, freeze-dried DP extract in powder (14 patients, active therapy) or capsules of lactose (10 patients, placebo group). Results showed a statistically lower symptom score, a significant increase in bronchial tolerance to the allergen and significant levels of DP-specific IgG in actively treated patients compared to those treated with placebo.