Effect of labeling of plasma lipoproteins with [3H]cholesterol on values of esterification rate of cholesterol in apolipoprotein B-depleted plasma

The fractional esterification rate of cholesterol in apolipoprotein B (apoB)-depleted plasma (FER HDL ) is a good indicator of particle size distribution in high density lipoprotein (HDL) and low density lipoprotein (LDL). However, there has been a discrepancy in the absolute values of FER HDL published by different laboratories. Because the main difference between the methods was in the labeling of lipoproteins with [ 3 H]cholesterol we investigated the effect of using Corning immunoplates and paper discs as carriers of the labeled unesterified cholesterol. We found that Corning plates trap some 3 H-labeled free cholesterol, which is released during incubation at 37°C. This means that this additional 3 H-labeled free cholesterol is exposed to lecithin: cholesterol acyltransferase (LCAT) for a shorter time and artificially decreases FER HDL . Using paper discs discarded before incubation as carriers of the 3 H-labeled free cholesterol results in complete labeling of HDL and thus yields higher values of FER HDL . —Dobiášová, M., L. Adler, T. Ohta, and J. Frohlich. Effect of labeling of plasma lipoproteins with [ 3 H]cholesterol on values of esterification rate of cholesterol in apolipoprotein B-depleted plasma. J. Lipid Res. 2000. 41: 1356–1357.