Innate Lymphoid Cells and Natural Killer Cells

Innate lymphoid cells (ILCs) and natural killer (NK) cells are important immune cells that protect against infection and malignancy. This chapter will describe the development and function of ILCs and NK cells, highlighting the similarities and differences between these innate cells and T cells. This chapter will also review the unique function of NK cells to combat intracellular infections and malignancy, termed “missing self.” Lastly, this chapter will chronicle the evidence that suggest a role of ILCs and NK cells in various rheumatologic disorders, including rheumatoid arthritis, systemic lupus erythematosus, juvenile idiopathic arthritis, macrophage activation syndrome/hemophagocytic lymphohistiocytosis, kawasaki disease, and multisystem inflammatory syndrome in children.