Brief Definit ive Report

Protection of mucosal surfaces depends on the delicate balance between rapid induction of in-nate immune responses and priming of adaptive immune responses. This early immune response has largely been thought to be orchestrated by NK cells, but recent studies have uncovered that the innate lymphocyte family is more complex and diverse than previously appreciated. It com-prises not only the prototypic innate lymphoid cell type 1 (ILC1), NK cells, and lymphoid tissue-inducer (LTi) cells but also nuocytes or natural helper cells and Rort+ ILCs. Recently, these lin-eages were classified into three ILC subsets: ILC1 (NK cell and IFN-–producing ILCs), ILC2 (nuocytes and natural helper cells), and ILC