Impaired antioxidant defense in hemoglobin E-containing erythrocytes: A mechanism protective against malaria?

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Abstract
Red blood cell (RBC) antioxidant defense was investigated in eight individuals with hemoglobin E (Six EE and two E‐B+ thalassemia) and compared to that in six individuals with thalassemia and ten normal subjects. Individuals with hemoglobin E had increased incubated Heinz body formation (68% ± 18%; p < 0.001) compared to normal and thalassemic RBC (10% ± 2% and 11% ± 5%, respectively). Stimulated pentose phosphate shunt activity was increased in the thalassemic and decreased in the hemoglobin E RBC as compared to normal. The 2,3‐diphosphoglycerate (DPG) content of the EE RBC was increased to 5.59 ± 0.69 μmol/ml RBC as compared to normal (4.51 ± 0.77; p < 0.001). In the EE RBC, there was a direct correlation between Heinz body formation and DPG content (r = 0.73). Ascorbic and dehydroascorbic acid (0.1 and 1.0 mM) were able to decrease the degree of Heinz body formation in the hemoglobin E RBC. Ascorbic acid (0.1 mM) prolonged the response of the pentose shunt. Thus impaired antioxidant defense may account for the persistence of the hemoglobin E gene in areas where malaria is endemic. Oxidant medications should be used with caution in individuals of Southeast Asian origin.