Leukotriene A4 hydrolase (LTA4H) acts primarily, if not exclusively, to hydrolyze leukotriene A4 (LTA4, i.e. 5S,6S-oxido-7E,9E,11Z,14Z-eicosatetetraenoic acid; IUPAC name 4-<nowiki/>{(2S,3S)-3-[(1E,3E,5Z,8Z)-1,3,5,8-Tetradecatetraen-1-yl]-2-oxiranyl}butanoic acid) to its diol metabolite, leukotriene B4 (LTB4, i.e. 5S,12R-dihydroxy-6Z,8E,10E,14Z-icosatetraenoic acid; IUPA name 5S,6Z,8E,10E,12R,14Z)-5,12-Dihydroxy-6,8,10,14-icosatetraenoic acid). LTB4 is an important recruiter and activator of leukocytes involved in mediation in inflammatory responses and diseases.  The enzyme also possess aminopeptidase activity, degrading, for example, the leukocyte chemotactic factor tripeptide, Pro-Gly-Pro (PGP); the function of the aminopeptidase activity of LTA4AH is unknown but has been proposed to be involved in limiting inflammatory reactions caused by this or other aminopeptidase-susceptible peptides.