Membrane phospholipid asymmetry and the adherence of loaded red blood cells

The phospholipids of the red cell membrane are asymmetrically distributed across the bilayer. Loss of this asymmetry by certain normal and pathological red cells is correlated with their increased adherence both in vitro and in vivo. Red cells loaded under conditions which result in loss of asymmetry adhere to cultured endothelial cells and are phagocytized in vitro by macrophages more readily than red cells loaded under conditions in which asymmetry is maintained. These results suggest that preserving phospholipid asymmetry during loading may prevent undesired in vivo interactions by reinfused red cell carriers.