NK cell subsets in autoimmune diseases

- NK cells exert both cell-mediated cytotoxicity and regulatory function.
- Various NK subsets including tissue-resident NK cells have been identified.
- The local tissue microenvironment shapes the properties and function of NK subsets.
- NK cells act as a two edged weapon in autoimmune diseases.
- The role of NK cells in autoimmune diseases correlates with different NK cell subsets and tissue microenvironment.

Natural killer (NK) cells are lymphocytes of the innate immune system. They not only exert cell-mediated cytotoxicity against tumor cells or infected cells, but also play regulatory role through promoting or suppressing functions of other immune cells by secretion of cytokines and chemokines. However, overactivation or dysfunction of NK cells may be associated with pathogenesis of some diseases. NK cells are found to act as a two edged weapon and play opposite roles with both regulatory and inducer activity in autoimmune diseases. Though the precise mechanisms for the opposite effects of NK cells has not been fully elucidated, the importance of NK cells in autoimmune diseases might be associated with different NK cell subsets, different tissue microenvironment and different stages of corresponding diseases. The local tissue microenvironment, unique cellular interactions and different stages of corresponding diseases shape the properties and function of NK cells. In this review, we focus on recent research on the features and function of different NK cell subsets, particularly tissue-resident NK cells in different tissues, and their potential role in autoimmune diseases.