Cerelli Mary Jane, Grimm Karen, Duan Xiaozhu, Mulberg Edie, Jalilie Maria, Sekella Phillip, Payes Marta, Cox Heather, Blick Kenneth E, Fang Kenneth C, Zychlinsky Emi
Diadexus, Inc., South San Francisco, CA 94080, United States.
University of Oklahoma College of Medicine, Department of Pathology, Oklahoma City, OK 73190, United States.
Clin Biochem. 2016 Apr;49(6):480-485. doi: 10.1016/j.clinbiochem.2015.11.018. Epub 2015 Dec 2.
Enzymatic activity of lipoprotein-associated phospholipase A2 (Lp-PLA2) mediates vascular inflammation in coronary heart disease (CHD). Calibration of Lp-PLA2 activity measurements using a recombinant enzyme was performed to assess intra- and inter-laboratory assay precision and accuracy in routine clinical settings.
Test performance assessment included recovery, analytical sensitivity, linear range, within-lab and site-to-site precision, interference, and analyte stability. Results using the Beckman-Coulter AU400 analyzer were compared to other chemistry analyzers.
Lp-PLA2 activity ranged from 84 to 303nmol/min/mL in 300 subjects, with 82.0% and 18.0% measurements below and at or above a cut-point of 225nmol/min/mL, respectively. Results of matched K2-EDTA plasma and serum (n=131) were similar with a slope of 1.00, y-intercept of 0.05, and R-value of 0.988. Mean recovery ranged from 90 to 106% of baseline after storage at different temperatures and time periods. Limit of detection was ≤10nmol/min/mL, without deviation from linearity between 10 and 382nmol/min/mL. Endogenous substances and medications did not interfere with the activity measurements. Overall intra- and inter-laboratory precision among three sites showed coefficients of variation of ≤3.8% and ≤5% respectively. Limit of quantitation was 1.3nmol/min/mL. Method comparison studies for multiple analyzers demonstrated slopes, intercepts or R(2) coefficients ranging from 0.96 to 1.06, -5.6 to 2.0, or 0.997 to 0.999, respectively.
Analytical performance of the calibrated PLAC(®) test for Lp-PLA2 enzyme activity assay in CHD is resistant to a wide variety of pre-analytical factors, with site-to-site reproducibility on multiple analyzers sufficient to standardize results in diverse laboratory settings.
脂蛋白相关磷脂酶A2（Lp-PLA2）的酶活性介导冠心病（CHD）中的血管炎症。使用重组酶对Lp-PLA2活性测量进行校准，以评估常规临床环境中实验室内部和实验室间检测的精密度和准确性。
检测性能评估包括回收率、分析灵敏度、线性范围、实验室内和不同地点间的精密度、干扰以及分析物稳定性。将使用贝克曼库尔特AU400分析仪的结果与其他化学分析仪的结果进行比较。
300名受试者的Lp-PLA2活性范围为84至303nmol/分钟/毫升，分别有82.0%和18.0%的测量值低于和等于或高于225nmol/分钟/毫升的切点。匹配的K2-EDTA血浆和血清（n = 131）的结果相似，斜率为1.00，截距为0.05，R值为0.988。在不同温度和时间段储存后，平均回收率为基线的90%至106%。检测限≤10nmol/分钟/毫升，在10至382nmol/分钟/毫升之间无线性偏差。内源性物质和药物不干扰活性测量。三个地点的总体实验室内和实验室间精密度分别显示变异系数≤3.8%和≤5%。定量限为1.3nmol/分钟/毫升。多种分析仪的方法比较研究表明，斜率、截距或R（2）系数分别为0.96至1.06、-5.6至2.0或0.997至0.999。
用于冠心病中Lp-PLA2酶活性测定的校准PLAC（®）检测的分析性能对多种分析前因素具有抗性，在多种分析仪上不同地点间的可重复性足以在不同实验室环境中使结果标准化。
