| Abstract: | The lipoxygenation of arachidonic acid in many different types of cells generates diverse mediators of hypersensitivity and inflammation. The leukotrienes represent one such family of mediators, which exert potent effects on smooth muscle, the microcirculation, and leukocytes. Leukocytes express distinct subsets of receptors for different leukotrienes. Transpeptidatic, peptidolytic, oxidative, and peroxidative pathways of leukocytes contribute substantially to the interconversion and biodegradation of leukotrienes. The 5-lipoxygenation of endogenous arachidonic acid appears to be a critical prerequisite for the activation of the function of leukocytes and some other cells. Natural and pharmacological inhibitors of 5-lipoxygenation in T lymphocytes noncytotoxically suppress the migration and transformation of the lymphocytes in response to antigens and mitogens. Lipoxygenase products of arachidonic acid thus fulfill important roles both as extracellular mediators and as functional intracellular constituents. |
