A Rapid, Kit-based Approach for LC-MS/MS Quantification of Apolipoprotein A1 in Plasma

■ ■ Excellent linearity, accuracy, and precision INTRODUCTION Apolipoprotein A1 (Apo A1) protein is a major component of High Density Lipoprotein (HDL) in plasma. Along with other lipoproteins, Apo A1 plays a key role in lipid metabolism.1 While typical levels of Apo A1 are >1.2 mg/mL for males and >1.4 mg/mL for females,2 reduced plasma concentrations of Apo A1 have been reported in patients at risk for certain types of heart disease.3–6 In addition, in Tangier Disease, which is characterized by a severe reduction in the amount of HDL, Apo A1 plasma concentration is only ~ 1% of those in normal subjects,7 that is, in the tens of microgram per mL range. Thus, measurements of Apo A1, and other lipoproteins are of high interest as potential biomarkers for cardiovascular disease. Traditionally, proteins have been quantified using ligand binding assays (LBAs). However, these immunoassays suffer from problems such as cross-reactivity, long antibody development time, reagent reliability, etc.