Bronchial responsiveness to mite allergen in atopic dermatitis without asthma

Eight patients with atopic dermatitis (AD) without a history of asthmatic episodes and 8 patients with mite-allergic bronchial asthma (BA) were subjected to bronchial inhalation challenge with a nonspecific stimulus (acetylcholine) and an immunologically specific stimulus (house dust mite allergen). AD patients had a significantly greater concentration of IgE (p less than 0.01) and antimite IgE antibody (p less than 0.05) than BA patients. Nonspecific bronchial hyperreactivities of AD patients distributed from normal to asthmatic range. After allergen challenge, all 8 AD patients and all 8 BA patients showed an immediate asthmatic response (IAR). The mite extract concentration to induce an IAR was significantly (p less than 0.01) greater in AD patients than in BA patients. A late asthmatic response was observed in 6 out of 8 BA patients, whereas it was not observed in any AD patient. Our results showed that AD patients are less reactive to a specific mite allergen than BA patients in spite of greater concentrations of antimite IgE antibody. They suggest that this difference in the bronchial reactivity to the allergen concerns the difference in the onset of clinical symptoms and that a certain level of bronchial hyperreactivity to the allergen is a prerequisite for the development of asthmatic symptoms.