Leukotriene

Leukotrienes are members of a family of eicosanoidinflammatory mediators produced in leukocytes by the oxidation of arachidonic acid (AA) and the essential fatty acideicosapentaenoic acid (EPA) by the enzymearachidonate 5-lipoxygenase.

Leukotrienes use lipid signaling to convey information to either the cell producing them (autocrine signaling) or neighboring cells (paracrine signaling) in order to regulate immune responses. The production of leukotrienes is usually accompanied by the production of histamine and prostaglandins, which also act as inflammatory mediators.

The role of one type of leukotriene (specifically, leukotriene D₄) is to trigger contractions in the smooth muscles lining the bronchioles; their overproduction is a major cause of inflammation in asthma and allergic rhinitis. Leukotriene antagonists are used to treat these disorders by inhibiting the production or activity of leukotrienes.