Oxidants from phagocytes: Agents of defense and destruction

Abstract

Of the systems that defend the host against invading microorganisms, the professional phagocytes (neutrophils, eosinophils, and mononuclear phagocytes) act in the most primitive fashion. Unlike cytotoxic lymphocytes and the complement system, which destroy their targets with a drop of poison, the professional phagocytes kill like Attila the Hun, deploying a battery of weapons that lay waste to both the targets and the nearby landscape with the subtlety of an artillery barrage. Among the most powerful of these weapons is a group of oxidizing agents that are produced by the phagocytes when they encounter invading microorganisms or other appropriate stimuli. These oxidants are reactive enough to destroy most biologic molecules and are responsible for much of the damage inflicted by phatocytes on both microorganisms and surrounding tissues at sites of infection or inflammation. In this article, I briefly review the nature of these oxidants, their mode of production, and their biologic effects, both good and bad.