Antioxidant deficit and enhanced susceptibility to oxidative damage in individuals with different forms of α-thalassaemia

α-Thalassaemia is a common red cell disorder in Taiwan, affecting 6-8% of Taiwanese. Previous studies have shown that reactive oxygen species are generated in increased amounts in thalassaemic red cells. This implies the possible alteration of redox status in thalassaemic patients, which may adversely affect their health. In the present study, the redox status of patients with α-thalassaemia trait and haemoglobin H (Hb H) disease was investigated. Lipid peroxidation, as measured by the level of plasma thiobarbituric acid reactive substances (TEARS), was increased in α-thalassaemic patients, with the highest level of TEARS in Hb H disease patient. The plasma levels of vitamin A, C, and E were significantly lower in α-thalassaemic patients than in controls. The overall antioxidant capacity in plasma was inversely correlated with the severity of α-globin gene defect: the more severe the form of α-thalassaemia, the lower the overall antioxidant capacity in plasma. Erythrocytes isolated from α-thalassaemia patients had lower levels of vitamin E, glutathione, catalase and superoxide dismutase. In addition, these α-thalassaemic red cells were more susceptible to hydrogen peroxide-induced lipid peroxidation and decrease in deformability. All these data suggest that the α-thalassaemic patients suffer from increased oxidative stress and antioxidant deficit, which may complicate the pathophysiology of α-thalassaemia.