Subpopulations of regulatory T-lymphocytes in the peripheral blood of patients with rheumatoid arthritis

Abstract

Rheumatoid arthritis (RA) is an inflammatory rheumatic disease associated with a dysfunction of the T cell-mediated tolerance and leading to the disability of working population. The regulatory CD4' T cells play an important role in the regulation of autoimmunity and can suppress immune responses. With that, there is no consensus on the content of these lymphocytes and their role in the pathogenesis of RA. Objective: The aim of the study was to assess the content ofperipheral blood regulatory Tcells (Treg) according to the expression of membrane markers CD4, CD25, CD127 and intracellular FOXP3 marker, as well as the expression of two functional molecules (CTLA-4 and CCR4) in Treg cells of patients with RA. Peripheral blood samples of RA patients (median age 65,5 years [54;68,3) and healthy controls (median age 58 years [44; 66]) were analyzed. Cell count and the expression level of molecules were assessed by flow cytometry. Peripheral blood samples of 36 RA patients and 20 healthy donors were analyzed. The number of the cells with Treg-associated phenotypes CD4⁺CD25hi and CD4⁺CD25hiCD127low/⁻ was higher in RA patients in comparison with healthy donors. Increased levels of RA CD4⁺ T cells expressing FOXP3 were also observed. This may be due to increasing in the number of CD4⁺FOXP3⁺CD25⁻ lymphocytes, whereas the content of RA CD4⁺FOXP3⁺CD25⁺ Treg cells was at the level of the control. The expression of the functional molecule CTLA-4 in Treg cells of patients with RA was not different from the control, while the expression level of the chemokine receptor CCR4 which provides migration of lymphocytes at sites of inflammation and barrier tissues was significantly increased in RA patients. Increase in the levels of certain Treg-associated lymphocyte populations were detected in peripheral blood of RA patients. During the natural course of RA, alterations in the level of the chemokine receptor CCR4 might indicate the enhanced lymphocyte migration.