NK cells get helpful

On page 941, Mailliard et al. show that natural killer (NK) cells exposed to the cytokine interleukin (IL)-18 commit to a life of helping rather than killing. According to the study, IL-18 creates interferon (IFN)-γ–producing, T helper (Th)-1–promoting NK cells, whereas IL-2 spawns killers.

NK cells are innate immune cells known for their ability to kill transformed or infected cells and to secrete cytokines including IFN-γ. Recently, these cells have been shown to influence the adaptive immune response by interacting with dendritic cells (DCs), thereby triggering either DC maturation or death. But the signals that determine whether NK cells kill DCs or help them mature are not completely understood. Also unknown is whether functionally specialized subsets of NK cells exist or whether individual NK cells are capable of different functions...