An enzymatic assay for lysophosphatidylcholine concentration in human serum and plasma

Several methods for measuring lysophosphatidylcholine (LPC) concentrations have been reported. However, these methods are not practical because they are either too complicated and/or too time-consuming for LPC determinations in human serum and plasma.

We have developed a new enzymatic LPC assay, which uses lysophospholipase, glycerophosphorylcholine phosphodiesterase and choline oxidase, and which determines the quantities of hydrogen peroxide generated in the presence of peroxidase using an oxidative chromogenic reagent and 4-aminoantipyrine.

Various samples were mixed with LPC assay reagents, and their changes in absorbance were measured. The present method produced a linear calibration line between LPC concentration and absorbance change. It also measured only LPC, and not other phospholipids such as phosphatidylcholine, sphingomyelin and lysophosphatidic acid. The within-run and between-run coefficients of variation were 0.3-0.7% and 0.7%, respectively. The recovery of exogenous LPC added to control serum was 99.5-102.1%. The correlation coefficient obtained in a comparison with a method for analyzing fatty acids was 0.9122.

The present method is simple, specific for LPC, and can be applied with an automatic analyzer. It may also be useful for further studies of the biological functions of LPC as well as clinical applications in various disorders.