TH2 cytokines profile in severe adult atopic dermatitis [PROFILO DI CITOCHINE A TIPO TH2 IN CORSO DI DERMATITE ATOPICA GRAVE DELL'ADULTO]

Atopic dermatitis is a disorder in which both type I and type IV reactions are involved. The disease is characterized by eczematous lesions and an aspecific infiltrate, often rich in eosinophils. Inflammatory infiltrate is constituted of T cells of the TH1 subset, but many authors showed that the TH2 subtype is important in the early phase of the disease. On the basis of our and of other group studies we investigated, at a molecular level, the mRNA expression of IL-4, IL-5, IL-2 and IFN-γ, in order to define the immunological pattern of the inflammatory infiltrate. IL-2 and IFN-γ are important mediators of delayed immunity, whereas IL-4 and IL-5 are involved especially in early immunity mechanisms, but can also participate in type IV reaction. Interleukin-4 and IL-5 are both produced by the T helper-2 lymphocyte subset. On the other hand the TH1 subset produces IL-2 and IFN-γ. IL-4 and IL-5 have many functions that could be summarized in eosinophils chemoattraction and maturation, and support to immunoglobulin-E production. IL-4 and IFN-γ have opposite functions on IgE production and are counter regulatory each other. 11 patients affected by atopic dermatitis and 5 normal patients have been biopsied. Biopsies and blood samples were taken within 48 hours from the appearance of new lesions and snap frozen in liquid nitrogen. Messenger RNA was extracted from biopsies, reverse transcribed and amplified. β-actin was used as a semiquantitative control. All patients showed a TH2-like cytokine pattern with IL-4 and IL-5 expression in both blood and skin samples. Two patients, biopsied several days later than the others, showed a reduction of IL-4 and IL-5 with an increased production of IL-2 and IFN-γ. We suggest that after an early immune reactions supported by a TH2-like cytokine secrection, there is a switching in the cytokine pattern to a TH1-like cytokine pattern.