title: On the expression of nitric oxide synthase by human macrophages. Why no NO?
abstract: The production of nitric oxide (NO) and its role in the anti-tumor and anti-microbial effects of rodent macrophages appears well established. In contrast, the circumstances required for its release from human monocytes/macrophages and its potential role in human pathology remain controversial. Evidence to be discussed suggests that NO is a redundant, autotoxic, immunosuppressive, and inefficient mediator of macrophage function. For these reasons, the expression of nitric oxide synthase as a rapid-response, high-output effector pathway may have been evolved out of the human monocyte/macrophage response repertoire or severely restricted in its expression. Hypothetical roles for a modest and circumscribed production of NO by human macrophages are proposed.
mesh_terms: D001120:Arginine / Q000502:physiology; D006801:Humans; D008264:Macrophages / Q000201:enzymology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*
chemical_list: D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase