14,15-LEUKOTRIENE D4

14,15-Leukotriene D₄ (14,15-LTD₄) is a member of an alternate class of LTs synthesized by a pathway involving the dual actions of 15- and 12-lipoxygenases (15- and 12-LOs) on arachidonic acid via 15-HpETE and 14,15-LTA₄ intermediates. 14,15-LTD₄ is classified as an eoxin (EXD₄), because it is formed mostly by eosinophils. However, mast cells and nasal polyps can synthesize 14,15-LTD₄ as well. Little is known about the physiological actions of 14,15-LTD₄. It has weak contractile activity on both guinea pig ileum and pulmonary parenchyma in contrast to the effects of 5-LO-derived LTs. However, in an in vitro permeability assay, 14,15-LTD₄ can increase vascular permeability of human endothelial cell monolayers, with similar potency to that of 5-LO-derived LTs, resulting in plasma leakage, a hallmark of inflammation.