Leukotriene B4

Overview

File:Eicosanoid synthesis.svg

Pathway of eicosanoid synthesis, including leukotriene B4.

Leukotriene B4 (LTB4) is a potent eicosanoid involved in the inflammatory response. It is a member of the leukotriene family, which are derived from arachidonic acid through the action of the enzyme 5-lipoxygenase. LTB4 plays a crucial role in the immune system by acting as a chemoattractant for neutrophils, guiding them to sites of infection or injury.

Biosynthesis

Leukotriene B4 is synthesized from arachidonic acid, a polyunsaturated fatty acid found in the phospholipids of cell membranes. The process begins with the conversion of arachidonic acid to 5-hydroperoxyeicosatetraenoic acid (5-HPETE) by the enzyme 5-lipoxygenase. 5-HPETE is then converted to leukotriene A4 (LTA4), an unstable epoxide intermediate. LTA4 is subsequently hydrolyzed by the enzyme leukotriene A4 hydrolase to form LTB4.

Function

Leukotriene B4 is a powerful chemoattractant and activator of neutrophils, a type of white blood cell essential for the body's defense against infections. It binds to specific G protein-coupled receptors on the surface of neutrophils, leading to their activation and migration towards the site of inflammation. LTB4 also enhances the production of reactive oxygen species and the release of lysosomal enzymes from neutrophils, contributing to the inflammatory response.

Clinical Significance

Due to its role in inflammation, leukotriene B4 is implicated in various inflammatory diseases, such as asthma, rheumatoid arthritis, and inflammatory bowel disease. Inhibitors of leukotriene synthesis or action, such as 5-lipoxygenase inhibitors and leukotriene receptor antagonists, are used in the treatment of these conditions to reduce inflammation and alleviate symptoms.

Related Pages

• Leukotriene
• Eicosanoid
• Arachidonic acid
• 5-lipoxygenase
• Neutrophil