Evaluation of new apolipoprotein C-II and apolipoprotein C-III automatized immunoturbidimetric kits

Background: Apolipoprotein C-II and apolipoprotein C-III play an important and complex role in plasma triglycerides metabolism, respectively, as inhibitor and activator of lipoprotein lipase. Thus, they appear to be suitable markers for clinical studies of triglyceride-rich lipoproteins and related cardiovascular risk. Our aim was to evaluate, for routine analysis, the accuracy to quantify these apolipoprotein in human sera. Methods: Precision (intra- and inter-run), limit of detection and quantification, linearity, common interferents (lipids, haemoglobin, bilirubin) and reference intervals were determined according to guidelines of the French Society of Clinical Biology and ISO Norm 5725 specifications. Results: Intra- and inter-run CVs were respectively less than 5.0% and 7.5%. Linearities extended from 10.8 mg/L to 112.9 mg/L for apolipoprotein C-II and from 31.8 mg/L to 375.5 mg/L for apolipoprotein C-III. Haemolysis (up to 227.6 mu mol/L haemoglobin) and lipemia (up to 19.3 mu mol/L triglycerides) do not interfere, contrary to bilirubin, which has a positive effect above 350 mu mol/L. Comparison of methods shows good agreement between immunoturbidimetric and electro-immunodiffusion methods for measuring apolipoprotein C-III in 62 samples within a wide range (n = 62, r = 0.954, y = 3.81 x -14.4). Conclusion: This study shows the reliability of these kits for measuring apolipoprotein C-II and apolipoprotein C-III in human sera, and their suitability for routine analysis. (c) 2006 The Canadian Society of Clinical Chemists. All rights reserved.