12-oxo Leukotriene B4 (12-Oxo-LTB4) is a potent pro-inflammatory lipid mediator classified as a dihydroxy fatty acid that is enzymatically derived from arachidonic acid metabolism via the 5-lipoxygenase (5-LO) pathway, and it promotes a diverse array of leukocyte functional responses including cellular aggregation, stimulation of transmembrane ion fluxes, enhancement of lysosomal enzyme release, superoxide anion generation, chemotaxis, and chemokinesis; 12-oxo Leukotriene B4 is an initial oxidative metabolite formed from Leukotriene B4 via the LTB4 12-hydroxydehydrogenase pathway, which undergoes rapid enzymatic conversion first to 10,11-dihydro-12-oxo-LTB4 followed by reduction of the 12-oxo group to yield 10,11-dihydro-LTB4, and this metabolite exhibits significantly reduced biological potency, being approximately 70-fold less potent than LTB4 in stimulating Ca2+ mobilization in human neutrophils (EC50 = 33 nM vs. 0.46 nM) and also markedly less effective at stimulating neutrophil migration (EC50 = 170 nM vs. 2.7 nM).