Membrane phospholipid asymmetry as a factor in erythrocyte-endothelial cell interactions

The tendency of human erythrocytes to adhere to vascular endothelial cells was assessed as a function of the transbilayer distribution of the phospholipids of the erythrocyte membrane, using erythrocyte ghosts in which transbilayer lipid arrangement was manipulated by varying the conditions under which the ghosts were prepared. By two different assays, ghosts with symmetric lipid bilayers adhered strongly to monolayers of cultured endothelial cells, whereas ghosts with normal asymmetric membranes, like normal erythrocytes, did not. These results provide direct evidence that changes in phospholipid asymmetry can alter the tendency of erythrocytes to adhere to endothelial cells, and therefore imply that transbilayer phospholipid arrangement may influence the behavior of erythrocytes in the circulatory system and may contribute to the formation of microvascular occlusions.