Adenosine, a Potent Natural Suppressor of Arachidonic Acid Release and Leukotriene Biosynthesis in Human Neutrophils

Leukotrienes (LTs) constitute a family of arachidonic acid (AA) metabolites with potent biological activities. Leukotriene B 4 and the cysteinyl-LTs (LTC 4 , -D 4 , and -E 4 ) have now been implicated in a number of physiological processes and inflammatory and allergic diseases (1). The early demonstration of an involvement of the cysteinyl-LTs as mediators of the bronchospasm in asthma has provided the impetus for the development of LT synthesis inhibitors and LT antagonists, and stimulated intensive research toward the understanding of the mechanisms of LT synthesis. While our knowledge of the biochemistry of LT synthesis and the enzymes involved has made remarkable progress, particularly with the identification and cloning of the proteins of the 5-lipoxygenase (5-LO) pathway, much remains to be learned about the complex mechanisms of regulation of the biosynthesis of these important mediators of inflammation and allergy.