Direct determination of lipoprotein cholesterol distribution with micro-scale affinity chromatography columns

Abstract

A quick and practical procedure based upon the principles of affinity chromatography has been developed and specifically adopted for the separation of serum lipoproteins into their respective alpha- and beta-lipoprotein fractions. The cholesterol, phospholipids, apoproteins, and triglycerides of these two lipoprotein fractions--the high-density lipoproteins (HDL) and lower density lipoproteins--can be directly measured independently after this separation. The sums of each fraction agree with total serum components when independently assayed. The affinity column is packed with heparin bound in high capacity to agarose. The beta-lipoproteins (low-density and very-low-density lipoproteins) and HDL-containing apolipoprotein E are absorbed to the column support; the alpha-lipoproteins (non-apolipoprotein E) pass through. The beta-lipoproteins are subsequently desorbed from the column support with saline. The direct assay of both the "protective" alpha-lipoprotein cholesterol (HDL cholesterol) and of the presumably atherogenic lower-density beta-lipoprotein cholesterol (LDL + VLDL cholesterol) permits calculation of a beta-: alpha-lipoprotein cholesterol ratio, which may better indicate a patient's risk of stroke or coronary heart disease than does the value for HDL cholesterol alone.