Leukotriene

**Semantic type:** Biologically Active Substance|Organic Chemical

**Definition:** Any eicosanoid produced by the oxidation of either eicosapentaenoic acid (EPA) or arachidonic acid (AA) by arachidonate 5-lipoxygenase in leukocytes. Leukotrienes act locally as autocrine or paracrine hormones to modulate immune responses and inflammation.