Beyond oxidative stress: an immunologist's guide to reactive oxygen species

Recent research has shed light on the complex regulation and functions of reactive oxygen species (ROS) signalling. In this Review, Nathan and Cunningham-Bussel provide an update on ROS biology, and they highlight some important roles for ROS in innate and adaptive immunity. Reactive oxygen species (ROS) react preferentially with certain atoms to modulate functions ranging from cell homeostasis to cell death. Molecular actions include both inhibition and activation of proteins, mutagenesis of DNA and activation of gene transcription. Cellular actions include promotion or suppression of inflammation, immunity and carcinogenesis. ROS help the host to compete against microorganisms and are also involved in intermicrobial competition. ROS chemistry and their pleiotropy make them difficult to localize, to quantify and to manipulate — challenges we must overcome to translate ROS biology into medical advances.