Development of an enzyme-linked immunosorbent assay for the quantification of O-Phosphoethanolamine in human plasma

O-Phosphoethanolamine (PEA) is an endogenous substance that is attracting interest as a biomarker for depression, and thus there is a need to develop a simple analytical method that specifically measures PEA. Therefore, this study aimed to develop a simple and specific enzyme-linked immunosorbent assay (ELISA) for PEA. Anti-PEA antibody was obtained by immunizing mice with an antigen conjugated with mercaptosuccinyl bovine serum albumin using m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester (MBS). In this assay, the PEA to be quantified is chemically modified by benzoyl chloride that is allowed to compete with a PEA-MBS-HRP conjugate for binding to a limited amount of an anti-PEA antibody, which was used to coat the wells of a microtiter plate. This ELISA shows a linear range of detection of 0.11-27 μM, and a limit of quantification of 0.144 μM. The anti-PEA antibody showed high affinity for benzoyl PEA. No detectable cross-reactivity was found with benzoyl 2-aminoethanol, O-phospho-l-tyrosine or benzoyl sphingosine-1-phosphate. The values of plasma PEA levels measured by this ELISA were comparable to those measured by HPLC, and a strong correlation was observed between the values determined by the two methods. The developed ELISA should provide a valuable new tool for the quantification of PEA in human plasma.