Macrophage phagocytosis of apoptotic PMNs. A nidus for transcellular biosynthesis. MPs or PMNs were preincubated with deuterium-labeled substrate (AA, EPA, and DHA, 100 ng each) before coincubation with macrophages for 1 hour at 37°C. Incubations were stopped with ice-cold MeOH and LM extracted. The levels of deuterium-labeled LM biosynthesized during the phagocytosis of apoptotic neutrophils were assessed by LC-MS/MS. (A) Representative MRM chromatograms of the identified LM. (B) Accompanying MS/MS spectra used for identification. (C) LM and precursor/pathway marker transition Q1-Q3 transitions along with mean ± SEM values for each of the mediators identified. The detection limit was ∼ 1 pg. *Below limits of detection. Cumulative values: (D) D-series resolvins, protectins, and maresins. (E) E-series resolvins and lipoxins. (F) Lipoxins. (G) Prostaglandins and thromboxanes. (C-G) Results are ± SEM; n = 5 distinct cell preparations.