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

Although atopic dermatitis (AD) is a common disease, its etiopathogenesis is not well known. The diagnosis of AD is based solely on the clinical criteria proposed by Hanifin and Rajka. In order to understand the immunological mechanisms involved in the pathogenesis of AD, we have classified the patients affected by this disease in four groups according to the results of skin prick-tests, specific IgE and patch-tests. This classification is intended to separate and compare the patients affected by AD according to the involvement of immunological type I and/or type IV mechanisms. Our results show that, although all the patients studied are clinically affected by AD, there are four different groups of patients who present an apparently diverse immunopathological mechanism. There is a group that seems to have an IgE mediated mechanism, another group that suggests a cell mediated mechanism, another group which seems to involve both mechanisms, and yet another group that apparently does not show any of the above mentioned mechanisms. In the present article we hypothesize and argue that the imbalance of the immune system is a consequence of the still unknown etiopathogenetic mechanism of AD, but perhaps not the cause of AD.

Contact dermatitis in subjects infected with HIV type 1.

In the course of HIV type 1 infection, up to 90% of patients may have skin disease. We studied a group of 26 HIV-infected patients (15 women, 11 men) with symptoms of skin disease or diffuse itching; they were patch tested for common contactants to determine whether allergic contact dermatitis was the cause of their symptoms. We found that approximately one third of HIV-1-positive patients with cutaneous symptoms not related to allergic contact dermatitis had positive patch tests for environmental contactants; in most of them this sensitization was directly related to skin symptoms.