CD 11 c lo B 220 interferon-producing killer dendritic cells are activated natural killer cells

10.1084/jem.20071451 During innate and adaptive immune responses, NK cells and DCs appear to play distinct, complementary, and synergistic roles. NK cells, by virtue of their capacity to respond without prior sensitization, can directly eliminate infected or transformed target cells and elaborate soluble factors (cytokines and chemokines) that recruit and amplify the infl ammatory response. DCs, in contrast, are the sentinels that, once activated, take up antigen, mature, and migrate to secondary lymphoid organs, where they present the processed antigen to naive T cells to initiate the adaptive immune response. In addition, DCs and NK cells can interact in a reciprocal fashion that results in the mutual activation of both types of cells (for review see reference 1 ). Mature DCs can prime NK cells to enhance their functional capacities ( 2 ), whereas activated NK cells secrete IFNthat up-regulates antigen presentation in DCs and can “ edit ” DC responses through the elimination of immature DCs ( 3, 4 ). In this way, NK cells and DCs represent two highly specialized cell types that interact in a complementary fashion. This cellular strategy could provide an additional level of control, because complete immune responses would not be effi ciently achieved by activation of either cell type in isolation. Recently, the functional dichotomy of DCs and NK cells has been challenged with the CORRESPONDENCE James P. Di Santo: disanto@pasteur.fr