Intracellular iron overload leading to DNA damage of lymphocytes and immune dysfunction in thalassemia major patients.

OBJECTIVES: To investigate the cause and effects of intracellular iron overload in lymphocytes of thalassemia major patients.

METHODS: Sixty-six thalassemia major patients having iron overload and 10 age-matched controls were chosen for the study. Blood sample was collected, and serum ferritin, oxidative stress; lymphocyte DNA damage were examined, and infective episodes were also counted.

RESULTS: Case-control analysis revealed significant oxidative stress, iron overload, DNA damage, and rate of infections in thalassemia cases as compared to controls. For cases, oxidative stress (ROS) and iron overload (serum ferritin) showed good correlation with R2  = 0.934 and correlation between DNA damage and ROS gave R2  = 0.961. We also demonstrated that intracellular iron overload in thalassemia caused oxidative damage of lymphocyte DNA as exhibited by DNA damage assay. The inference is further confirmed by partial inhibition of such damage by chelation of iron and the concurrent lowering of the ROS level in the presence of chelator deferasirox.

CONCLUSION: Therefore, intracellular iron overload caused DNA fragmentation, which may ultimately hamper lymphocyte function, and this may contribute to immune dysfunction and increased susceptibility to infections in thalassemia patients as indicated by the good correlation (R2  = 0.91) between lymphocyte DNA damage and rate of infection found in this study.