Deferiprone therapy in homozygous human β-thalassemia removes erythrocyte membrane free iron and reduces KCl cotransport activity

Deposition of free iron is a characteristic feature of β-thalassemia (β-thal) red blood cells believed to play an important role in the generation of oxidative injury to the cell membrane. Increased red blood cell KCl cotransport, reduced K content, and cell dehydration are also found in β-thal red blood cells. It is not known, however, whether deposition of free iron plays a role in these membrane transport changes. To explore this issue, we studied-both in vitro and in vivo-the effect on KCl cotransport of removing red blood cell membrane free iron from β-thal erythrocytes. Eleven patients with β-thal major who underwent long-term transfusion and were treated with deferiprone (75 mg/kg/day) for 9 months participated in the study. Deferiprone therapy removed membrane free iron from β-thal erythrocytes, which was followed by reduced KCl cotransport activity. The reduced KCl cotransport activity was accompanied by an increase in the red blood cell K content. These data suggest that the increased activity of KCl cotransport in β-thal red blood cells is mediated by the deposition of membrane free iron, a mechanism that may be attenuated by deferiprone therapy.