PB2390 THE ROLE OF T REGULATORY CELLS IN THE PATHOGENS AND IMMUNITY OF BETA‐THALASSEMIA MAJOR PATIENTS

Abstract

Background:The basis of the pathogenesis of the immunodeficiency in thalassemia is iron overload and allogenic stimulation caused by multiple blood transfusions. T regulatory cells (Tregs) are a component of the immune system that constitutes a key mechanism in maintaining peripheral self‐tolerance through the control of auto‐reactive lymphocyte activation.Aim:To determine the frequency of Tregs in children and adolescents with β‐thalassemia major and assessed their relation to the clinical and laboratory characteristics of patients including transfusion therapy, iron overload and alloimmunization.Methods:Sixty β‐TM patients studied focusing on transfusion history and chelation therapy. Hematological and biochemical data including markers of hemolysis and serum ferritin were assessed. Patients’ records were analyzed for the presence of alloantibodies. Assessment of T regulatory cells was done using flow cytometry. Patients were compared with 30 healthy controls.Results:The percentages of CD4+ T lymphocytes and Tregs were significantly reduced in β‐TM patients compared with the control group (p < 0.05). Patients with patients with splenectomy, heart disease and pulmonary hypertension risk had lower levels of these cells than those without. The percentage of Tregs was decreased among patients with serum ferritin ≥2500 μg/L compared with patients below this cutoff and in patients with history of alloimmune antibodies. There were significant negative correlations between Tregs and each of indirect bilirubin and ferritin levels while they were positively correlated with WBCs counts and hemoglobin.Summary/Conclusion:Conclusion: Children and adolescents with β‐TM may encounter a state of immune dysfunction. Low frequency of Tregs in β‐TM patients may contribute to the formation of alloantibodies. Alterations in Tregs are more evident in relation to iron overload. It is important to assess the suppressive activity of these cells in standard proliferation assays to examine whether their function is disrupted in β‐TM together with the alteration in their frequency or not.