Diagnostic value of immune cholesterol as a marker for atherosclerosis

The serum of patients with coronary atherosclerosis contains circulating immune complexes including low-density lipoproteins (LDLs). We have developed a technique for the evaluation of LDL content in circulating immune complexes by measuring total cholesterol levels in polyethylene glycol precipitates (immune cholesterol). In the present study, the value of immune cholesterol in the diagnosis of atherosclerosis was compared with that of other laboratory parameters, such as total cholesterol levels, triglycerides, LDL cholesterol, high-density lipoprotein cholesterol, lipoprotein(a), and apolipoproteins B and A-1.

Immune cholesterol and the other parameters were determined in blood samples from 200 patients with documented coronary and extracoronary atherosclerosis. Coronary atherosclerosis was assessed by coronary angiography; stenoses in the aortic arch and branches and in lower-limb arteries were evaluated by angiography and ultrasonography.

Only immune cholesterol and the ratio of apolipoprotein B to apolipoprotein A-1 correlated significantly with the severity of coronary atherosclerosis. The accuracy of the diagnosis of coronary atherosclerosis by immune cholesterol was 78%, considerably higher than that of other laboratory parameters. Use of a combined parameter consisting of immune cholesterol, LDL cholesterol, and the patient's age increased the diagnostic accuracy to 81%. A high level of immune cholesterol is characteristic not only of coronary atherosclerosis but also of extracoronary atherosclerosis. The sensitivity, specificity and accuracy of the diagnosis of extracoronary atherosclerosis were even higher than those for coronary atherosclerosis.

Immune cholesterol may be employed as a novel marker in the diagnosis of advanced atherosclerosis.