Interactions of Human Myeloid Cells with Natural Killer Cell Subsets In Vitro and In Vivo

Figure 1

NK-cell preactivation in secondary lymphoid organs by dendritic cells (DCs). Mature DCs preactivate NK cells in secondary lymphoid tissues but are not killed in the process and continue to prime adaptive immune responses. They achieve this by simultaneously transmitting IL-15-dependent activating signals via transpresentation of this cytokine in distinct domains of their synapse with DCs, while inhibiting NK-cell lysis by engaging inhibitory receptors via MHC class I molecules occurs in other domains of the synapse center. In addition, DC-derived IL-12 and type I IFN (IFN-α/β) increase IFN-γ production and cytotoxicity of conjugated NK cells. NK cells home to these sites after development in the bone marrow, while mature DCs migrate there at increased frequency from peripheral tissues after their maturation.