[Structural and functional alterations of the erythrocyte membrane in sickle cell anemia]

The low solubility of deoxyhemoglobin S is responsible for sickle cell disease. Membrane alterations associated with intracellular polymerization of HbS are progressively irreversible, leading to shortened red cell viability, abnormal rheologic behaviour of blood in the microcirculation, disseminated vascular occlusion and hypoxic organ damage. The alterations in membrane molecular architecture include mainly cell shape abnormality (sickle shaped cytoskeleton), loss of membrane material, changes on the red cell surface (adherence to vascular endothelium) and loss of lipid bilayer asymmetry (exposition of procoagulant phospholipids). Functional alterations of the membrane permeability to cations lead to dehydration of the red cells. The resulting increase in HbS concentration and polymerization is responsible for the irreversibility of the lesions.