Isolation and partial characterization of two abnormal human plasma lipoproteins: LP-X1 and LP-X2.

Abstract Two abnormal lipoproteins (LP-X 1 and LP-X 2 ) rich in free cholesterol and phospholipid have been isolated from the plasma of nine different patients with obstructive jaundice. As isolated, both lipoproteins were devoid of low density lipoproteins as judged by agar electrophoresis. In addition, they were free of apoB as judged by double immunodiffusion. However, LP-X 1 exhibited a higher phospholipid to protein ratio and a lower hydrated density than LP-X 2 . The levels of LP-X 1 and LP-X 2 in plasma were measured in three patients studied for 14 days after corrective surgery for obstructive liver disease. The level of both these abnormal lipoproteins decreased after surgery until the twelfth day when they were completely absent from the plasma of these patients. The rates of this decrease for the two particles are significantly different. These differences in metabolic, chemical, and physical properties of LP-X 1 and LP-X 2 establish their identity as two distinct and unique lipoprotein particles.