The lipids of the erythrocyte in paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is a disorder characterized by the production of abnormal erythrocytes (PNH-E). The PNH-E undergoes early intravascular destruction which appears to be related to an intrinsic membrane defect that results in extreme sensitivity to lysis by complement. The lipids of the PNH-E have been evaluated because of the variable results reported in the past. This study shows a normal content of cholesterol and lipid phosphorus with a normal distribution of the phospholipids except for a slight increase in lysophosphatidyl choline (LPC) when measured using the complete lipid extract of the PNH-E. Fractionation of the lipid extract over a silicic acid column produced an alteration in the distribution of the phospholipids, with LPC and sphingomyelin increasing, and the other phospholipids decreasing. These alterations were seen only when the phospholipids were fractioned over a silicic acid column and were clearly an in vitro phenomenon. The levels of plasmalogen and malonaldehyde were normal, unlike those seen with oxidant stress. Fatty acid analysis of the phospholipids showed small but consistent changes: increased 16:0 and decreased 18:2. The total glycosphingolipids were slightly decreased in the patients with severe PNH. The results support and extend previous lipid data indicating abnormalities in the phospholipids of the PNH-E. The alterations of the phospholipids with fractionation correlate with previous whole cell data that suggest lipid instability in the PNH-E.