Development of a highly sensitive liquid chromatography - mass spectrometry method to quantify plasma leukotriene E 4 and demonstrate pharmacological suppression of endogenous 5-LO pathway activity in man.

•A robust ultra-sensitive SPE-UPLC-MS/MS method for LTE4 in human plasma was successfully developed•For the first time we demonstrated that pharmacological inhibition of 5-LO pathway activity can suppress basal endogenous levels of LTE4 in plasma•The ability to quantify plasma LTE4 provides an alternative biomarker to urine LTE4 to assess endogenous 5-LO pathway activity in man.