Background: Atopic dermatitis (AD) is an inflammatory skin disease whose lesions can have two stages: acute and chronic. In skin biopsies a biphasic pattern of cytokine expression has been shown, Th2 in acute lesions and Th1 in chronic AD lesions.
Objective: We investigated the expression of an activation marker and a homing receptor, as well as cytokine production, in different peripheral blood T cell subpopulations from AD patients with chronic (Group A) and acute lesions (Group B) and controls.
Methods: We evaluated 26 adult AD patients (12 Group A, 14 Group B) and 14 non-atopic controls. IgE was measured by immunoassay. CD4, CD8, cutaneous-lymphocyte-associated antigen (CLA) and human leucocyte antigen (HLA)-DR expression, and cytokine production (IL-2, IL-13, IFN-gamma, TNF-alpha, IL-10, IL-4) were analysed in mononuclear cells by flow cytometry.
Results: In Group B there was a significant increase in eosinophil levels and a non-significant increase in IgE. In Group A we found an increase in CLA(+)CD4(+) cells (8.19+/-1.84) compared with controls (4.83+/-0.53) (P<0.05) and CD4(+)HLA-DR(+) cells in the CLA(+) subpopulation (45.54+/-15.40) compared with controls (30.49+/-6.07) (P<0.05). In the CLA(+)CD4(+) subpopulation, there was a significant increase in IL-4, IL-13 and TNF-alpha production in Group B (12.46+/-7.7, 11.26+/-5.97, 43.92+/-15.55) compared with controls (5.34+/-3.50, 4.54+/-1.78, 19.29+/-9.97) with no differences in Group A.
Conclusion: Greater immunological differences were detected in peripheral blood from patients with acute compared with chronic lesions, especially in the circulating T cell-subset with skin tropism that preferentially responded to cutaneous allergens. This is the first demonstration of phenotypic changes in circulating CLA(+) T cells between AD patients with acute and chronic lesions.