Chemiluminescence immunoassay for sensing lipoprotein-associated phospholipase A2 in cardiovascular risk evaluation

Abstract

Background: Lipoprotein-associated phospholipase A2 (Lp-PLA₂) is a novel inflammatory biomarker, which is useful as an adjunct identification tool for cardiovascular disease. However, the important limitation of the conventional enzyme-linked immunosorbent assay (PLAC ELISA) for Lp-PLA₂ assay is its relatively low sensitivity and time consuming. A method to measure the Lp-PLA₂ simply, rapidly and sensitively is essential for predicting cardiovascular events in clinic.

Methods: We took advantage of magnetic separation integrated with chemiluminescence to detect Lp-PLA₂. The concentration of Lp-PLA₂ was measured through a one-step process by mixing antibody labelled magnetic beads, antigen and antibody at one time.

Results: Our method realized the sample to answer within 17 min. The detection limit and measurement range were 0.18 ng/ml and 0.18-1350 ng/ml, respectively. The specificity assay showed that no appreciable interference was observed for the substances of bilirubin, triglyceride, hemoglobin, rheumatoid factor and human anti-mouse antibody up to the concentrations of 40 mg/dl, 1000 mg/dl, 2000 mg/dl, 1500 IU/ml and 30 ng/ml, separately. We also tested 122 clinical samples using our method, presenting good overall correlations (R² = 0.979) to the PLAC ELISA. It is worth mentioning that, our method was faster, had a wider range of measurement and higher sensitivity compared with the PLAC ELISA.

Conclusions: The Lp-PLA₂ assay is straightforward, sensitive and precise, which is highly suitable to further explore the clinical performance of Lp-PLA₂ in studies of cardiovascular risk management.

Keywords: Cardiovascular disease; Chemiluminescence immunoassay; Lp-PLA(2); Magnetic separation.