Double-faced cell-mediated immunity in β-thalassemia major: stimulated phenotype versus suppressed activity

Abstract

In this study, the immunologic abnormalities of Iranian beta-thalassemia major patients were characterized, considering their clinical parameters including splenectomy status and iron overload. Serum samples and peripheral blood mononuclear cells were collected from 28 patients and 30 age- and sex-matched healthy individuals. Patients with thalassemia showed significantly increased absolute lymphocyte counts compared with the control group. An increased number of activated T cells and higher levels of serum neopterin were also observed in thalassemia patients, which suggest chronic stimulation of immune system. On the contrary, T-cell proliferation and interleukin 2 (IL-2), interferon gamma (IFN-gamma), and IL-4 production were suppressed in patients compared to controls. Patients with high serum ferritin levels produced significantly less IFN-gamma and IL-2, indicating the immunosuppressive effect of iron overload in beta-thalassemia patients. The serum levels of tumor necrosis factor alpha and absolute counts and percentages of B and T cells were higher in splenectomized patients; however, serum levels of neopterin significantly decreased in splenectomized patients compared to the non-splenectomized group. Taken together, T lymphocytes express activated phenotype in polytransfused beta-thalassemia major patients, while T cell proliferation and effector function are significantly suppressed. Multiple blood transfusion and continuous immune stimulation could be responsible for making such a double-faced immune response.