Abnormal phospholipid molecular species of erythrocytes in sickle cell anemia

As the lipid composition of cell membranes has significant effects upon cellular function, we hypothesized that the membranes of sickle cells might have a distorted lipid composition. Accordingly, we analyzed the molecular species of the choline and ethanolamine glycerophospholipids, the fatty acid composition of the total phospholipids and of the five major individual phospholipids of erythrocytes from 8 patients with sickle cell anemia and from 14 normal subjects. Of the 31 molecular species identified for each subclass of the glycerophospholipids, 12 were found to be distinctly abnormal. Sickle cells contained more molecular species with saturated and monounsaturated fatty acid at the sn-2 position and fewer molecular species with polyunsaturated fatty acids at the sn-2 position. The values ranged from 20 to 60% above or below normal values. In diacyl choline glycerophospholipids (outer membrane leaflet), sickle erythrocytes contained lower amounts of the 16:0-18:2 species and higher 16:0-18:1 and 16:0-16:0 species. In diacyl ethanolamine glycerophospholipid (inner membrane leaflet), sickle erythrocytes had lower amounts of 18:0-22:6; 16:0-22:4; 18:0-18:2; 18:1-18:2; and 18:1-20:3. In phosphatidylcholine and phosphatidylethanolamine, sickle erythrocytes contained less linoleic acid, less docosahexaenoic acid (30-40%) and more oleic and palmitic acids (20- 30%) compared to normal erythrocytes. These same differences were seen also in the total phospholipids. Our data demonstrated distinct abnormalities of the phospholipid molecular species composition in the membrane lipids of sickle erythrocytes. These defects might have a role in one or more known metabolic abnormalities of sickle cell disease including cation imbalance, dehydration, disturbed membrane phospholipid asymmetry, and hypercoagulability. Furthermore, detailed information of the phospholipid molecular species composition of normal erythrocytes was provided.