Sequential microultracentrifugation of lipoproteins in 100 microliters of serum

A method is described for sequential separation of high density, very low density, and low density lipoproteins (HDL, VLDL, and LDL, respectively) from 100 microliters of serum, using an air-driven ultracentrifuge (Airfuge, Beckman). Cesium chloride was used for density adjustment. Precision-within-series (coefficient or variation) depended on the cholesterol concentration in the lipoprotein fractions, greater than 1 mmol/l, less than 2.3%. Recovery within-series was nearly 100%. The results (mmol/l) correlate well with those from an electrophoretic-enzymatic procedure (alpha-HDL: 1.49 +/- 0.34 vs. 1.48 +/- 0.33, r = 0.949; pre-beta-VLDL: 0.58 +/- 0.42 vs. 0.59 +/- 0.45, r = 0.975; beta-LDL: 3.11 +/- 0.93 vs. 3.07 +/- 0.88, r = 0.990; n = 48). Recovery of lipoprotein cholesterol from this group was 99.2 +/- 4.2%. A combination of ultracentrifugation with high-performance thin-layer chromatography for determination of lipoprotein-lipid profiles was achieved with recoveries of 98-101%, as evaluated from a group of healthy men (n = 31) and women (n = 38). The entire procedure is, therefore, suitable for compositional studies on lipoproteins from small serum samples. In particular, capillary serum from children of all ages, even from premature neonates, is quite adequate.