Measurement of Lipoprotein-Associated Phospholipase A2 by Use of 3 Different Methods: Exploration of Discordance between ELISA and Activity Assays

Abstract

Quantitative analysis of Lp-PLA₂ concentration and activity by LC-MS/MS assays provided key insight into resolving the well-documented discordance between Lp-PLA₂ concentration (determined by immunoassay) and activity. Quantitative detection of Lp-PLA₂ by immunoassay appears to be strongly inhibited by interaction of Lp-PLA₂ with lipoprotein. Together, the results illustrate the advantages of quantitative LC-MS/MS for measurement of Lp-PLA₂ concentration (by SISCAPA) and activity (by direct product detection).