Abstract

Background: Oxidative modification of low-density lipoprotein (LDL) plays a key role in the pathogenesis of atherosclerosis. LDL(–) is present in blood plasma of healthy subjects and at higher concentrations in diseases with high cardiovascular risk, such as familial hypercholesterolemia or diabetes.

Methods: We developed and validated a sandwich ELISA for LDL(–) in human plasma using two monoclonal antibodies against LDL(–) that do not bind to native LDL, extensively copper-oxidized LDL or malondialdehyde-modified LDL. The characteristics of assay performance, such as limits of detection and quantification, accuracy, inter- and intra-assay precision were evaluated. The linearity, interferences and stability tests were also performed.

Results: The calibration range of the assay is 0.625–20.0 mU/L at 1:2000 sample dilution. ELISA validation showed intra- and inter-assay precision and recovery within the required limits for immunoassays. The limits of detection and quantification were 0.423 mU/L and 0.517 mU/L LDL(–), respectively. The intra- and inter-assay coefficient of variation ranged from 9.5% to 11.5% and from 11.3% to 18.9%, respectively. Recovery of LDL(–) ranged from 92.8% to 105.1%.

Conclusions: This ELISA represents a very practical tool for measuring LDL(–) in human blood for widespread research and clinical sample use.

Clin Chem Lab Med 2008;46:1769–75.