HEMOLYSIS IN PRIMARY LIPOPROTEIN-LIPASE DEFICIENCY

A slight to moderate hemolysis is often present in plasma from patient s with primary lipoprotein lipase (LPL) deficiency. To determine the n ature of this hemolysis, we measured erythrocyte hypo-osmotic fragilit y, plasma free hemoglobin, and phospholipid composition in 26 patients with primary LPL deficiency and 21 unrelated controls. In some patien ts, these investigations were completed by erythrocyte cytoskeletal pr otein determinations and abdominal echography, Osmotic fragility was s imilar between control subjects and patients. However, there was a sig nificantly increased concentration of plasma free hemoglobin in primar y LPL deficiency (0.282 +/- 0.331 v 0.048 +/- 0.038 g/L in controls, P < .005), In LPL-deficient patients, an increase of plasma lysophospha tidylcholine concentration (12.6% +/- 5.8% v 6.4% +/- 1.9% in controls , P < .0001) was also found. The protein composition of the erythrocyt e membrane skeleton was abnormal in some LPL-deficient patients and sp lenomegaly was present in 12, but these abnormalities did not correlat e with plasma free hemoglobin levels. Bilirubin and haptoglobin levels were also within physiologic ranges in these patients, suggesting tha t the observed hemolysis did not result from hypersplenism. It appears likely that the accumulation of lysophosphatidylcholine was due to an impairment in the reverse metabolic pathway converting lysophosphatid ylcholine back to phosphatidylcholine. Collectively, these data, along with a positive correlation between plasma free hemoglobin and lysoph osphatidylcholine levels (r = .58, P = .0001), suggest that the hemoly sis observed in primary LPL deficiency is mediated to some extent by t he abnormally elevated concentration of lysophosphatidylcholine. Copyr ight (C) 1995 by W.B. Saunders Company