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 (R-2>0.99) in the concentration range of 2.00x10(-5)-2.00x10 (1) and 2.40x10 (4)-2.40 U/mL for ox-Lp(a) and ox-LDL, respectively. The detection limits for ox-Lp(a) and ox-LDL were 2.40x10(-6) and 3.00x10(-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.