To elucidate abnormalities in lipid metabolism in patients with primary biliary cirrhosis (PBC), plasma lipoproteins and apoproteins were analyzed in 10 such patients. Lipoprotein X was present in sera from five of the patients. Another abnormal lipoprotein of slow a-mobility on agarose gel electrophoresis was observed in sera of eight of the patients. The slow a-lipoprotein was distributed in the range of densities between low density and high density lipoproteins and was rich in apoprotein E. This abnormal lipoprotein of PBC was observed in those in Stages I1 and I11 but not in those in Stage I. The amounts of slow a-lipoprotein correlated to the levels of serum apoprotein E and to total cholesterol. Determination of apoprotein concentrations in serum of PBC patients revealed increases of apoproteins E and C-I1 and a decrease of apoprotein A-11. In conclusion, lipoprotein abnormalities in PBC patients were characterized by increased levels of apoprotein E and appearance of an abnormal lipoprotein of slow a-mobility in addition to well-known lipoprotein X.
Hyperlipidemia is a common complication of primary biliary cirrhosis (PBC). Mean serum cholesterol levels in a series of 83 cases of symptomatic PBC and 21 asymptomatic PBC were reported to be 377 and 285 mg per dl, respectively (1). Xanthelasma reportedly occurred in 21% of PBC patients and xanthoma in 6% (2). Xanthelasma and xanthoma were expected to occur in most PBC patients in whom the total serum lipids exceeded 1,300 and 1,800 mg per dl, respectively (3).
Two types of abnormal lipoproteins have been detected in sera of patients with PBC, i.e., lipoprotein X (LP-X)