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Physiologically important secondary modifications of red cell membrane in hereditary spherocytosis-evidence for in vivo oxidation and lipid rafts protein variations.

Margetis P, Antonelou M, Karababa F, Loutradi A, Margaritis L, Papassideri I

Faculty of Biology, Department of Cell Biology and Biophysics, University of Athens, Panepistimiopolis, Athens 15784, Greece.

Hereditary spherocytosis (HS) is a heterogeneous group of disorders. The abnormal red cell morphology (resulting in shortened cell survival) is due to a primary deficiency in spectrin, ankyrin-1, band 3 or protein 4.2. Secondary protein deficiencies are often observed and may be involved in the outcome of the disease. In the present study, we searched for secondary erythrocyte membrane protein alterations in HS, including the lipid raft associated proteins and the oxidative index. For this purpose, 12 patients with clinical and laboratory diagnosis of mild to typical HS were examined. Erythrocyte membrane ghosts and skeletons were subjected to SDS-PAGE and immunoblotting analysis using antibodies against red cell membrane proteins and DNP moiety, after 2,4-dinitrophenylhydrazine derivatization. Protein deficiencies, degradation, aggregation and enhanced binding of cytoplasmic components, band 8, hemoglobin and immunoglobulins G to the membrane as well as increased oxidative index, were found in the majority of the HS patients. Proportion of the membrane- and skeleton-bound globin was oxidized/denatured Hb or hemichromes and crosslinkings. Some HS membranes are deficient in lipid rafts proteins and contain sorcin. A context of these distortions is more pronounced in typical HS cases compared to the mild ones. Similar defects in thalassemia and senescent RBCs are dictated by increased oxidative stress and are positively correlated with perturbations in membrane properties. These data add some new insight in the field of HS pathophysiology and clinical variability.

Published 9 April 2007 in Blood Cells Mol Dis, 38(3): 210-20.
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