Bronchial and skin reactivity in asthmatic patients with and without atopic dermatitis.

It is unclear whether the presence and severity of atopic dermatitis (AD) is predictive for the occurrence and severity of early and late asthmatic responses to inhaled allergens. The aim of this study was to compare the bronchial effects of allergen inhalation challenge in allergic asthma (AA) and atopic dermatitis. We therefore studied these responses in: nine patients with mild-to-moderate AA without AD; eight patients with mild-to-moderate AA and mild AD; eight patients with severe AD and mild AA; and eight patients with severe AD without AA. Allergen challenge was performed by inhaling doubling doses until the dose provoking a 20% fall in forced expiratory volume in one second (PC20) was reached. The late asthmatic reaction (LAR) was defined as a fall of >20% in peak expiratory flow (PEF) between 3 and 8 h after the challenge. All but four of the patients with severe AD without AA developed an early asthmatic response (EAR). A LAR was seen in all patients with severe AD and mild AA, in four patients with mild AD and mild-to-moderate AA, and in three patients with mild-to-moderate AA without AD. The LAR was most pronounced in patients with a combination of mild AA and severe AD. This could be explained, in part, by a decreased skin sensitivity in these patients, which made the Cockcroft formula for prediction of PC20 allergen less accurate in such patients. We conclude that patients with severe atopic dermatitis and mild asthma are at risk for developing pronounced late asthmatic responses after allergen exposure. This suggests that eosinophils activated in atopic dermatitis also predispose to airway inflammation.