The role of membrane lipids in the survival of red cells in hereditary spherocytosis

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Abstract
Red cells in hereditary spherocytosis (HS) have a decreased ratio of membrane surface area to cell volume and therefore a spheroidal shape. This abnormality in shape predisposes them to pooling and destruction in the spleen. Although splenectomy prevents hemolysis in HS, the red cell defect, as manifested by spheroidicity, increased autohemolysis, excesive permeability to sodium, and hypermetabolism, persists. The role of membrane lipids in these manifestations in vitro and in cell survival in vivo was examined. Before splencetomy, and in spite of the presence of a young cell population, the cholesterol and phospholipid content of HS red cells is decreased. After splenectomy lipid values are similar to those obtained in normal subjects with spleens. However, after splenectomy for conditions other than HS the lipid content of red cells is greater than normal. Thus, when compared with the red cells of patients without HS who have also undergone splenectomy, HS cells after splenectomy are deficient in both cholesterol and phospholipid. Obstructive jaundice causes an increase in membrane lipid, primarily cholesterol, and a decrease in the osmotic fragility of normal red cells. When HS red cells are transfused into patients with obstructive jaundice they also become less osmotically fragile. Moreover, when incubated in obstructive jaundice serum, they gain cholesterol. This acquistion of membrane lipid in vitro does not result in a change in their rate of glucose utilization or sodium efflux. However, the transformation to a less spheroidal shape in vivo permits them to traverse better the splenic circulation and survive longer.