Development of a rapid, quantitative method for LDL subfractionation with use of the Quantimetrix Lipoprint LDL System

Background: Recent evidence suggests that the presence of small, dense LDL is independently associated with increased risk of developing coronary arte ry disease. Current methods to subfractionate LDL are time-consuming and/or technically demanding. Therefore, we have sought the development of a less complex LDL, subfractionation procedure. Methods: LDL subfractions were separated using the Quantimetrix Lipoprint(T M) LDL System. High-resolution 3% polyacrylamide gel tubes were scanned den sitometrically (610 nm) with a Helena EDC system. A computerized method to identify and quantitatively score the resolved LDL subfractions was develop ed. Results from the Quantimetrix method were compared using 51 plasma samp les with values obtained by nondenaturing gradient gel electrophoresis (NDG GE) and nuclear magnetic resonance (NMR) spectroscopy. Results: LDL subfractionation scores correlated significantly (P <0.05) wit h triglyceride, HDL-cholesterol, apolipoprotein B100, and LDL-cholesterol/a polipoprotein B100 (r = 0.591, -0.392, 0.454, and -0.411, respectively). Fo r 51 samples, the Quantimetrix method classified 21 with small, 14 with int ermediate, and 16 with large LDL. Of the 21 samples classified as small by Quantimetrix, 20 (95%) were classified as small (n = 18) or intermediate (n = 2) by NDGGE. All of the 16 specimens classified as large by Quantimetrix were either large (n = 14) or intermediate (n = 2) by NDGGE. LDL score was inversely correlated (r = -0.674; P <0.0001) with LDL particle size determ ined by NMR spectroscopy. Conclusions: A quantitative method for the assessment of LDL particle size phenotype was developed using the Quantimetrix Lipoprint LDL System. The me thod can be performed in less than 3 h in batch mode and is suitable for ro utine use in clinical laboratories. (C) 2001 American Association for Clini cal Chemistry.