Characterization of high density lipoproteins in human cholestasis.

High density lipoproteins (HDL) of plasma from patients with long-standing cholestasis were studied by several methods including crossed immunoelectrophoresis, gel filtration, and zonal ultracentrifugation. The crossed immunoelectrophoretic pattern against anti-HDL was characterized by the presence of several immunoprecipitates, in striking contrast to the pattern formed by normal HDL. One of these precipitates corresponded to a lipoprotein species dominated by apoprotein A-II (apo A-II). Zonal ultracentrifugation of cholestatic plasma showed a decrease of HDL and a disappearance of the normal delineation of HDL2 and HDL3. In addition a new component designated HDL1-C was observed. Consistent results were found at studies of the molecular size distribution of cholestatic HDL by gel filtration on Sephadex G-200. The lipid and apoprotein composition of isolated cholestatic HDL fractions differed considerably from normal. Most notable were the high proportions of phospholipids and free cholesterol and the occurrence of the apoprotein E (arginine-rich protein) in remarkably high amounts especially in the abnormal HDL1-C.