Cutaneous late-phase reaction to environmental antigen in patients with atopic dermatitis

Intradermal testing with 7 environmental allergens was performed on 71 patients with atopic dermatitis (AD) with respiratory atopy (RAT) and 30 pure AD patients, and the cutaneous late-phase reaction (CLPR) was observed several to 48 h after challenge. CLPR was not seen in pure AD. In AD patients with RAT, CLPR was positive in 29 of 71 patients. No macroscopic eczematous lesions appeared. All CLPR-positive patients showed RAST scores of 2 or more. We assume that CLPR can be an exacerbating factor in AD with RAT, while it is not directly involved in pure AD.