Changes in human high density lipoproteins in patients with extra-hepatic biliary obstruction

Plasma high density lipoproteins (HDL) from patients with obstruction of the common bile duct were studied by crossed immunoelectrophoresis and isoelectric focusing. All cholestatic HDL fractions were rich in phospholipids (51.5 ± 9%) with high proportions of free cholesterol (13.8 ± 1.5%). Moreover, crossed immunoelectrophoresis of sera against anti-Apo A revealed the presence of multiple immunoprecipitates sharply contrasting with the pattern formed by normal sera. Tandem crossed immunoelectrophoresis against anti-Apo A and anti-Apo B was performed with whole serum and with the HDL fraction from various cholestatic subjects. Crossed identity was observed for two of these precipitates, which could be explained by the decrease in HDL stability due to the detergent effect of bile salts. The most noteworthy changes found in cholestatic patients appeared to be the apolipoprotein pattern of HDL. Both Apo AI (48%) and Apo AII (5.5%) were greatly diminished and Apo E was present in remarkably high amounts (39%) with two additional isoforms (Apo E' 1 and Apo E' 2).