Novel enzymatic method for assaying Lp-PLA2 in serum

Abstract Background Measurement of lipoprotein-associated phospholipase A 2 (Lp-PLA 2 ) can be used as an adjunct to traditional cardiovascular risk factors for identifying individuals at higher risk of cardiovascular events. This can be performed by quantification of the protein concentration using an ELISA platform or by measuring Lp-PLA 2 activity using platelet-activating factor (PAF) analog as substrate. Here, an enzymatic Lp-PLA 2 activity assay method using 1- O -Hexadecyl-2-acetyl- rac -glycero-3-phosphocholine (rac C 16 PAF) was developed. Methods The newly revealed substrate specificity of lysoplasmalogen-specific phospholipase D (lysophospholipase D (LysoPLD)) was exploited. Lp-PLA 2 hydrolyzes 1- O -Hexadecyl-2-acetyl- sn -glycero-3-phosphocholine (C 16 PAF) to 1- O -Hexadecyl-2-hydroxy- sn -glycero-3-phosphocholine (LysoPAF). LysoPLD acted on LysoPAF, and the hydrolytically released choline was detected by choline oxidase. Results Regression analysis of Lp-PLA 2 activity measured by the enzymatic Lp-PLA 2 activity assay vs. two chemical Lp-PLA 2 activity assays, i.e. LpPLA 2 FS and PLAC® test, and ELISA, gave the following correlation coefficients: 0.990, 0.893 and 0.785, respectively ( n  = 30). Conclusion Advantages of this enzymatic Lp-PLA 2 activity assay compared with chemical Lp-PLA 2 methods include the following; (i) only requires two reagents enabling a simple two-point linear calibration method with one calibrator (ii) no need for inhibitors of esterase-like activity in serum.