A cytochrome P450 monooxygenase involved in the metabolism of the pro-inflammatory lipid mediator leukotriene B4 (LTB4) (PubMed:16380383, PubMed:24632148). Hydroxylates at the omega-1 and omega-2 positions LTB4. This oxidation step leads to LTB4 inactivation, which is postulated to be a crucial part of the resolution of inflammation (PubMed:16380383, PubMed:24632148). Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (CPR; NADPH-ferrihemoprotein reductase) (PubMed:16380383, PubMed:24632148). leukotriene B4 + O2 + reduced [NADPH--hemoprotein reductase] = 18-hydroxy-leukotriene B4 + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] leukotriene B4 + O2 + reduced [NADPH--hemoprotein reductase] = 19-hydroxy-leukotriene B4 + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Lipid metabolism; leukotriene B4 degradation. Highest level in polymorphonuclear leukocytes and dendritic cells. Detectable in lymph nodes, spleen, bone marrow and peripheral blood. Highly expressed in ovary. Very low level in liver, kidney, and smooth muscle. Expressed in neutrophils (at protein level). Up-regulated in bone marrow-derived dendritic cells by bacterial lipopolysaccharide (LPS), a ligand for toll-like receptor 4 (TLR4), and by poly(I:C), a ligand for TLR3. Mice are born at the expected Mendelian rate. No visible phenotype. Belongs to the cytochrome P450 family.