Heterogeneity of atopic dermatitis defined by the immune response to inhalant and food allergens

Although atopic dermatitis (AD) is a common disease, its etiopathogenesis i s not well known. The diagnosis of AD is based solely on the clinical crite ria proposed by Hanifin and Rajka. In order to understand the immunological mechanisms involved in the pathogenesis of AD, we have classified the pati ents affected by this disease in four groups according to the results of sk in prick-tests, specific IgE and patch-tests. This classification is intend ed to separate and compare the patients affected by AD according to the inv olvement of immunological type I and/or type IV mechanisms. Our results show that, although all the patients studied are clinically aff ected by AD, there are four different groups of patients who present an app arently diverse immunopathological mechanism. There is a group that seems t o have an IgE mediated mechanism, another group that suggests a cell mediat ed mechanism, another group which seems to involve both mechanisms, and yet another group that apparently does not show any of the above mentioned mec hanisms. In the present article we hypothesize and argue that the imbalance of the i mmune system is a consequence of the still unknown etiopathogenetic mechani sm of AD, but perhaps not the cause of AD.