Frequency and activation of CD4+CD25 FoxP3+ regulatory T cells in peripheral blood from children with atopic allergy

Background: Atopic allergy is among the immune tolerance-related disorders resulting from a failure of the regulatory network. Regulatory T cells (Tregs) play a leading role in the development of homeostasis in the immune system. The aim of this study was to determine the role of Tregs in the pathogenesis of atopic diseases in children by exploring the relationship between Treg frequency, activation markers and the clinical manifestations of the disease.

Methods: Twenty allergic and 50 healthy children were enrolled to the study. Peripheral blood mononuclear cells were stained with monoclonal antibodies (anti-CD25-CD4-CD127-FoxP3-CD69-CD71) and evaluated using flow cytometry. Tregs were identified as CD4+CD25(+/high)FoxP3+CD127- T cells.

Results: The percentage of Tregs in allergic patients (2.3%) was significantly decreased in comparison to healthy controls (4.6%, p = 0.003). The frequency of Tregs in patients with symptoms of atopic dermatitis and/or food allergy (1.7%) was significantly lower than in patients without these symptoms (2.9%, p = 0.04). A significant correlation between the percentage of Tregs and the sIgE serum concentration was observed (p = 0.037). Relative fluorescence intensities of FoxP3 expression in allergic patients were higher than in healthy controls (p = 0.00004). The frequency of CD4+CD25(high)CD127-CD71+ cells did not differ between the groups.

Conclusions: Tregs display substantial deficiencies in atopic children, especially in children with multiorgan involvement, compared to patients with single organ manifestations. Additionally, there is an association between Tregs and the sIgE serum concentration. Better identification and characterization of Tregs in allergy is needed as they limit responses to foreign antigens, thereby minimizing T cell-mediated immunopathology in allergic diseases.