ABNORMAL PHOSPHOLIPID MOLECULAR-SPECIES OF ERYTHROCYTES IN SICKLE-CELL-ANEMIA

As the lipid composition of cell membranes has significant effects upo n cellular function, we hypothesized that the membranes of sickle cell s might have a distorted lipid composition. Accordingly, we analyzed t he molecular species of the choline and ethanolamine glycerophospholip ids, the fatty acid composition of the total phospholipids and of the five major individual phospholipids of erythrocytes from 8 patients wi th 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 mole cular species with saturated and monounsaturated fatty acid at the sn- 2 position and fewer molecular species with polyunsaturated fatty acid s at the sn-2 position. The values ranged from 20 to 60% above or belo w normal values. In diacyl choline glycerophospholipids (outer membran e 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 ethan olamine glycerophospholipid (inner membrane leaflet), sickle erythrocy tes had lower amounts of 18:0-22:6; 16:0-22:4; 18:0-18:2; 18:1-18:2; a nd 18:1-20:3. In phosphatidylcholine and phosphatidylethanolamine, sic kle erythrocytes contained less linoleic acid, less docosahexaenoic ac id (30-40%) and more oleic and palmitic acids (20-30%) compared to nor mal erythrocytes. These same differences were seen also in the total p hospholipids. Our data demonstrated distinct abnormalities of the phos pholipid molecular species composition in the membrane lip ids of sick le erythrocytes. These defects might have a role in one or more known metabolic abnormalities of sickle cell disease including cation imbala nce, dehydration, disturbed membrane phospholipid asymmetry, and hyper coagulability. Furthermore, detailed information of the phospholipid m olecular species composition of normal erythrocytes was provided.