Principles of NK cell/DC crosstalk: The importance of cell dialogue for a protective immune response

A cooperative dialogue between natural killer (NK) cells and dendritic cells (DCs) has been recently described. They help each other to acquire their complete functions, both in the periphery and in the secondary lymphoid organs. In vitro, IL-12, IL-18, IL-15, and type-I IFN are implicated in the activation, proliferation, and cytotoxicity of NK cells by mature DCs, while TNF-α secreted by NK cells is involved in the maturation of DCs. Not completely clarified cell-to-cell contacts are also implicated in this cross-talk. Thus, NK cell activation allows the killing of transformed or infected cells in the periphery, but may also be important for the generation of adaptive immunity. Recent works suggest that they may play a key role in polarizing a Th1 response. This dialogue between DCs and NK cells may be further exploited in immunotherapy aimed to boost immune response.