Detection of allergen-specific Th2A-cells in peripheral blood of patients with allergic diseases

There is an increase in the incidence of allergic diseases all over the world including Russia. The most common allergic disorders are allergic rhinitis, atopic dermatitis and bronchial asthma. Despite the differences in symptoms, the pathogenesis of all allergic diseases is based on activation of the Th2 immune response. A heterogeneous population of CD4+ lymphocytes is developed in response to allergen. Recently, a group of researchers described a population of terminally differentiated allergen-specific T cells that co-express CRTh2, CD161, and produced high levels of IL-5 and IL-9. This population was called pro-allergic “Th2A” cells. The aim of the present work was to assess the contents of allergen-specific Th2A cells and Th2 lymphocytes in allergic bronchial asthma, atopic dermatitis and allergic rhinitis. The study included 10 patients with allergic rhinitis, 9 cases of atopic dermatitis, 12 patients with allergic bronchial asthma and 8 healthy individuals. Phenotyping of Th2A cells (CD4+CD45RO+CD27-CRTh2+CD161+) and Th2 lymphocytes (CD4+CD45RO+CRTh2+) from mononuclear cells of peripheral blood was performed by flow cytometry. There were no significant differences in the number of Th2 lymphocytes, either between the donor’s group and all groups of patients with allergic diseases, or between groups of patients with different allergic diseases. A 3- to 4-fold increase in the number of Th2A cells compared to healthy individuals was observed in groups of patients with allergic rhinitis, atopic dermatitis, and a 2-fold increase was found in the group of patients with bronchial asthma. Moreover, the level of allergen-specific Th2A cells in patients with allergic rhinitis and in atopic dermatitis was significantly higher than in patients with bronchial asthma. This finding reflects probable involvement of Th2A cells in the pathogenesis of allergic diseases. Th2A cells may be also considered as a potential marker for tracing the course of allergic disease and assessing the efficiency of therapy, thus requiring further research in the field.