ABNORMALITIES OF SERUM APO A1 CONTAINING LIPOPROTEIN PARTICLES IN PATIENTS WITH PRIMARY BILIARY-CIRRHOSIS

Patients with primary biliary cirrhosis (PBC) do not appear to have an increased risk of cardiovascular disease despite elevations in serum cholesterol. Recent evidence has pointed to LpA1 (an apo Al containing particle which contains apo Al but not apo A2) in protecting against atherosclerosis. The aim of this study was to investigate apo A1 conta ining particles in the serum of patients with PBC. Lipids and apolipop roteins were measured in 31 patients with PBC (30 females) and 27 cont rol subjects (26 females). Patients were divided into 3 groups: group 1 with bilirubin < 18 mu mol/l (n = 17); group 2 with bilirubin > 18 m u mol/l (n = 11); and group 3 with end stage liver disease (ESLD, n = 3). As expected group 1 and 2 patients had higher total cholesterol, H DL cholesterol and phospholipids than control subjects. Apo B and apo A1 concentrations were similar to control subjects. However, LpA1 was greatly increased: 0.96 g/l (0.60-1.50), median (range) in group 1 and 1.09 g/l (0.75-1.33) in group 2 versus 0.62 g/l (0.45-0.93) for contr ols both P < 0.005 and the percentage of total apo A1 in the LpA1 frac tion was increased: 54.8% (37.9-63.4) in group 1 and 55.7% (47.8-73.7) in group 2 versus 36.8% (25.1-49.1) for controls, both P < 0.005. Apo A2 concentration was reduced in group 1 0.38 g/l (0.30-0.51) and grou p 2 0.31 g/l (0.14-0.58) versus controls 0.43 g/l (0.36-0.57), P < 0.0 5 and P < 0.005 respectively. Patients with ESLD had reduced HDL chole sterol, apo A1, LpA1 and apo A2 compared to controls. These results su ggest that PBC is associated with an altered distribution of apo A1 fa vouring an increased concentration of the protective LpA-I particles. Increased LpA1 concentration may be one of the factors contributing to the paradoxically low incidence of atherosclerosis in PBC patients. ( C) 1997 Elsevier Science Ireland Ltd.