Non-haem iron-mediated oxidative stress in haemoglobin E beta-thalassaemia

Haemoglobin (Hb) E beta-thalassaemia is a common thalassaemic disorder in Southeast Asia and is very common in the eastern and north-eastern parts of India. The disease cause rapid erythrocyte destruction due to the free radical mediated injury but factors for the oxidative injury are not clearly known. We investigated the free reactive iron (non-haem) mediated insult in Hb E beta-thalassaemia.

Thirty Hb E beta-thalassaemic patients (age range, 3 to 15 years) who had undergone blood transfusion at least 1 month prior to sampling and 32 normal healthy individuals (age range, 18 to 30 years) were included in this study. We estimated the ferrozine detected intracellular erythrocytic free reactive iron (nonhaem iron), reduced glutathione (GSH), glutathione reductase activity, cellular damage marker serum thiobarbituric acid reacting substances (TBARS) and also serum ferritin using standard methods.

We found that the erythrocytic free reactive iron was significantly higher (P <0.001) in Hb E beta patients and was about 30% more than in controls. The elevated level of erythrocytic non-haem iron was associated with a high level of serum TBARS which was about 86% higher in patients than in controls. The serum ferritin level was also significantly higher (P <0.001) compared to controls. The erythrocytic reduced glutathione level was significantly lower (P <0.001) at about 65% less in the patients' group and the erythrocytic glutathione reductase enzyme was also found to be significantly lower (P <0.001) in Hb E beta-thalassaemia.

We concluded that a significantly elevated level of erythrocytic free reactive iron and lipid peroxidation end product was associated with low erythrocytic GSH level. This reflects non-haem iron mediated cellular damage in Hb E beta-thalassaemia.