HDL biology
A direct LDL isolation technique offers a simpler alternative for measuring CETP activity (Clin Chim Acta 1997)
Original title: Direct isolation of labeled low density lipoproteins for the determination of cholesteryl ester transfer protein activity
A direct LDL isolation (d-LDL) technique was developed to measure CETP activity in one step, using specific immunoprecipitation of VLDL, IDL, and HDL to directly determine radiolabeled cholesteryl esters transferred from exogenous HDL3 to LDL, avoiding the ultracentrifugation or apo-B precipitation steps normally required. CETP activity was assayed with both exogenous and endogenous lipoproteins and compared against the standard ultracentrifugation-based reference method, with similar intra- and inter-assay variability between the two techniques. Strong positive correlations were found between the direct isolation and ultracentrifugation methods for both exogenous and endogenous lipoprotein CETP activity assays (r=0.972, p=0.0001 and r=0.965, p=0.0001, respectively). The authors conclude that the direct LDL isolation technique offers an easy and accurate way to directly measure CETP-mediated cholesteryl ester transfer from HDL to LDL in normotriglyceridemic plasma.
Original abstract
The measurement of the activity of cholesteryl ester transfer protein (CETP), is of high clinical interest and this study reports the use of a direct LDL isolation (d-LDL) technique to determine in one step the amount of radiolabeled cholesteryls esters ([3H]-CE) transferred from exogenous HDL3 to LDL, avoiding the conveniences of the usually used ultracentrifugation or precipitation of apo-B containing lipoproteins in the CETP methodologies. The d-LDL technique providing a specific immunoprecipitation of VLDL, IDL and HDL allowed to directly determine the [3H]-CE transferred on LDL (d-[3H]-CE-LDL). Two methodologies were assayed for the CETP activity using either exogenous or endogenous lipoproteins, and the results with the d-LDL technique were compared with those obtained using the ultracentrifugation (u-[3H]-CE-LDL) considered as the reference method. The intra- and inter-assays were similar in both techniques for the two CETP activity assays. Strong positive correlations were established between values obtained with d-[3H]-CE-LDL and u-[3H]-CE-LDL isolation procedures for CETP activities with exogenous or endogenous lipoproteins (r = 0.972; p = 0.0001 and r = 0.965; p = 0.0001 respectively). In conclusion, the d-LDL technique represents an easy and accurate procedure to measure directly, in normotriglyceridemic plasmas, the amount of [3H]-CE transferred from HDL to LDL by the CETP.
Summary written by cetpinhibition.org from the published abstract; figures as published. Page updated 19 August 2026. Methods.