Unbalanced T-cell subsets in pediatric patients with beta-thalassemia.

BACKGROUND:Beta-thalassemia major is an autosomal recessive disorder in hemoglobin synthesis. Ineffective erythropoiesis is the main characteristic of the disease, which results in anemia following the extensive destruction of red blood cells. Chronic antigenic stimulation following frequent blood transfusions lead to immune abnormalities, especially regarding T cells, which is one of the reasons for the high susceptibility to infection in beta-thalassemia. METHODS:Six pediatric patients and six age- and sex-matched healthy children were selected. Immunophenotyping of functional T-cells was performed using flow cytometry with staining for surface and intracellular markers. The proliferative response of T lymphocytes was also investigated after labeling with CFSE and following stimulation with anti-CD3 and anti-CD28. RESULTS:Examination of T lymphocyte subpopulations showed a significant increase in regulatory T cells (Tregs) in beta-thalassemia patients. Hence, the Treg:Tcons (conventional T cells) and Treg:CD8 ratios were significantly increased. In addition, a significant increase in CD8 T cell proliferation activity was observed. Multivariate analysis showed a significant association of central memory cells with serum ferritin levels and the duration of transfusion. In particular, patients with cytomegalovirus (CMV) infection exhibited a significant increase in CD4 central memory cells. CONCLUSION:Patients with beta-thalassemia have functionally distinct CD4 and CD8 T cell subsets imbalances, and this may contribute to their high susceptibility to infections and immune dysregulation.