A sensitive chemiluminescence imaging immunoassay for simultaneous detection of serum oxidized lipoprotein(a) and low density lipoprotein.

BACKGROUND Oxidized lipoprotein(a) [ox-Lp(a)] and oxidized low density lipoprotein (ox-LDL) levels have been reported to be useful predictors of cardiovascular events. The study developed a chemiluminescence (CL) imaging immunoassay method for simultaneously detecting serum concentrations of ox-Lp(a) and ox-LDL. METHODS Ox-Lp(a) and ox-LDL levels were measured by CL imaging immunoassay using a disposable immunosensor array as the carrier and a charge-coupled device as the detector, and were studied in 46 acute coronary syndromes (ACS) patients, 58 stable coronary artery disease (CAD) and 61 control subjects. RESULTS This method showed good linear relations (R²>0.99) in the concentration range of 2.00×10⁻⁵-2.00×10⁻¹ and 2.40×10⁻⁴-2.40 U/mL for ox-Lp(a) and ox-LDL, respectively. The detection limits for ox-Lp(a) and ox-LDL were 2.40×10⁻⁶ and 3.00×10⁻⁵ U/mL, respectively. The intra- and inter-assay coefficients of variation (CV) were 4.90%-6.76% and 7.11%-10.06% for ox-Lp(a), and 5.01%-6.04% and 5.47%-9.77% for ox-LDL, respectively. The mean recovery was 99.31% for ox-Lp(a) and 99.57% for ox-LDL, respectively. Significant correlations were observed between ox-Lp(a) levels detected by CL imaging immunoassay and ELISA, and between ox-LDL levels detected by the two methods, respectively. Furthermore, ox-Lp(a) and ox-LDL levels increased in stable CAD, and especially in ACS. CONCLUSIONS The CL imaging immunoassay provided a simple, sensitive and reliable method for the simultaneous determination of serum ox-Lp(a) and ox-LDL. The clinical monitoring ox-Lp(a) and ox-LDL levels may possess distinctly clinical value for assessment of CAD risk.