Clinical and prognostic significance of T-regulatory cells and CD28 expression on T-lymphocytes in patients with immune thrombocytopenia

Background. The leading role in the control of the immune response and peripheral tolerance is played by T-regulatory cells, as well as costimulatory molecules C28 on T-lymphocytes, which are necessary for effective activation. While T-regulatory cells in immune thrombocytopenia (IT) are actively studied in order to find an effective influence on their functions, publications on the study of costimulation processes in this disease are quite rare. Given the pronounced immunosuppressive effect of glucocorticosteroids (GCS) used in the treatment of patients with IT, it seems particularly relevant to study the role of T-regulatory cells and the expression features of costimulatory C28 molecules on T-lymphocytes to expand our understanding of the disease pathogenesis and justify new approaches to treating patients in real clinical practice.Aim. To evaluate the clinical and prognostic significance of T-regulatory cells and C28 expression on peripheral blood T-lymphocytes in patients with newly diagnosed IT and resistant to GCS therapy.Materials and methods. The content of T-regulatory cells and C28 expression features on peripheral blood T-lymphocytes were studied by flow cytometry in 18 patients with newly diagnosed IT and 19 patients resistant to GCS therapy. Thirty healthy individuals were examined as a control group.Results. A significant (p ˂ 0.05) decrease in the content of classical T-regulatory cells (C4+C25+hiC127–) was revealed both in patients with newly diagnosed IT and in those resistant to GCS, while no significant differences were found in C8+C28– peripheral T-regulatory cells level in patients with IT of both groups compared to healthy individuals. In patients with IT of both groups, a significant increase in the proportion of T-helper (p 05; p ˂ 01, respectively) and cytotoxic C8+ (p ˂ 0.05; p ˂ 0.01, respectively) T-lymphocytes expressing C28 was found compared to normal values. The level of T-helper lymphocytes (C4+C28–) was 2 times higher in the group of patients with resistance to GCS compared to newly diagnosed IT patients, and 3.5 times higher compared to healthy individuals.Conclusion. T-regulatory cells and expression of C28 costimulatory molecules play an important role in the immunopathogenesis of IT. A significant increase in the content of the C4+C28null lymphocyte population (C4+C28–) in the peripheral blood of IT patients can be a prognostic criterion for GCS resistance, which may require a revision of the treatment strategy.