Isolation and characterization of an abnormal alpha slow-moving high-density lipoprotein subfraction in serum from children with long-standing cholestasis.

An abnormal high-density lipoprotein (HDL) subfraction, detected during periods of mild jaundice in the serum of seven children with chronic cholestasis from birth, was isolated and characterized. This fraction, identified by its slow alpha electrophoretic migration, is present in addition to normal HDL and differs from the abnormal HDL previously described in cholestatic syndromes. It is devoid of apolipoprotein B but is precipitated by phosphotungstate-MgCl2. These properties allowed its isolation by double selective precipitation. This subfraction is undetectable with this procedure in the serum of healthy subjects, is rich in cholesterol, and contains a large amount of apolipoprotein E, which may explain its precipitation by phosphotungstate-MgCl2. These apo E-containing HDL may play a major role in the lipid metabolism of patients with long-standing cholestasis during periods of mild jaundice.