Decrease in circulating Th17 cells correlates with increased levels of CCL17, IgE and eosinophils in atopic dermatitis.

Background: Clinical significance of circulating CD4(+) T cell subsets, including T-helper (Th)1, Th2, Th17 and regulatory T (Treg) cells, in patients with atopic dermatitis (AD) remains unclear. No previous studies have simultaneously evaluated the four T cell subset profiles in AD.

Objective: The aim of the present study was to explore whether the percentage of these four subsets of CD4(+) T cells correlate to the severity parameters of AD patients.

Methods: Intracellular expression of interferon (IFN)-γ, interleukin (IL)-4, IL-17 and forkhead box P3 (Foxp3) in CD4(+) T cells was evaluated in peripheral blood mononuclear cells from normal controls and patient with AD as well as with chronic eczema using a flow cytometer. Serum CCL17 levels were measured as an objective severity parameter of AD together with percentage of eosinophils and serum IgE levels.

Results: In AD patients, the number of Th1 (IFN-γ(+)) and Th17 (IL-17(+)) subsets was significantly decreased, but that of Th2 (IL-4(+)) and Treg (Foxp3(+)) subsets was similar to that of normal controls. The T cell subset profiles of patients with chronic eczema were not different with those of normal controls. The frequency of Th17cells, particularly that of the IFN-γ(nega)IL-17(+) subset, showed a significant negative correlation with CCL17, IgE and eosinophil levels in AD patients. This was, however, not the case in Th1, Th2 and Treg cells.

Conclusions: Decreased circulating Th17 cells might contribute to activity of AD.