Leukotriene B4 is a pro-inflammatory dihydroxy fatty acid derived from arachidonic acid and produced from leukocytes in response to inflammation. Agonist of the BLT1 and BLT2 receptors. Promotes adhesion and activation of leukocytes at the endothelium, and stimulates production of pro-inflammatory cytokines and mediators. May be a factor in inflammatory diseases, and shows antiviral activity towards DNA viruses and retroviruses.