LIPID-MEMBRANE PEROXIDATION IN BETA-THALASSEMIA MAJOR

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  • 1 January 1976
    • journal article
    • research article
    • Vol. 47  (3) , 495-505
Abstract
The composition of membrane lipids was studied in 17 splenectomized and 8 unsplenectomized patients with .beta.-thalassemia major and compared to normal controls. The results showed: a nearly 2-fold increase in total cell lipids; a reduction in the percentage, but not the absolute amount of phosphatidylethanolamine and a corresponding increase in phosphatidylcholine in the lipids; a considerable increase in the percentage of the saturated fatty acid, palmitic acid and a reciprocal decrease in the polyunsaturated fatty acid, arachidonic acid; a 2-fold increase in the amount of malonyldialdehyde (MDA) generated after H2O2 threat to the RBC when calculated either per gram Hb or per cell; no change in the amount of MDA generated when calculated per .mu.g of membrane P at risk per cell; and a considerable decrease in serum .alpha.-tocopherol (vitamin E) levels. Thalassemic erythrocytes contain more lipid per cell which is susceptible to peroxidation. In addition, the distribution of fatty acids in these cells suggests that autooxidation of that lipid may have occurred. Autooxidation may be initiated by free radicals, which are constantly formed in the normal red cell and may be especially prevalent when unstable Hb are present. The low mean cell Hb count or some other intracellular defect of thalassemic cells may allow such potent oxidants to find their way to the cell membrane. Vitamin E, a biologic antioxidant is decreased in these patients, and clinical supplementation may be indicated to prevent some of the membrane damage in thalassemia.