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-γ, TNF-α, 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-α 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.