Following an infection or stress, NK cells produce IFNγ that in turn primes macrophages to release pro-inflammatory cytokines (e.g., IL-1β, IL-12, IL-18, IL-23) and to produce high amount of reactive oxygen and nitrogen species (ROS and RNS, respectively), for example through the up-regulation of the NADPH oxidase and the inducible nitric oxide synthase (iNOS), respectively. This evidence concerns the gene NOS2 and infection.