Leukotriene

Leukotrienes are fatty signaling molecules. They were first found in leukocytes (hence their name). One of their roles (specifically, leukotriene D₄) is to trigger contractions in the smooth muscles lining the trachea; their overproduction is a major cause of inflammation in asthma and allergic rhinitis. Leukotriene antagonists are used to treat these diseases by inhibiting the production or activity of leukotrienes.