WASH maintains NKp46+ ILC3 cells by promoting AHR expression.

Innate lymphoid cells (ILCs) communicate with other haematopoietic and non-haematopoietic cells to regulate immunity, inflammation and tissue homeostasis. How these ILC lineages develop and are maintained is not clear. Here we show that WASH is highly expressed in the nucleus of group 3 ILCs (ILC3s). WASH deletion impairs the cell pool of NKp46+ ILC3s. In NKp46+ ILC3s, WASH recruits Arid1a to the Ahr promoter thus activating AHR expression. WASH deletion in ILC3s decreases the number of NKp46+ ILC3s. Moreover, Arid1a deletion impedes AHR expression and impairs the maintenance of NKp46+ ILC3s. Therefore, WASH-mediated AHR expression has a critical function in the maintenance of NKp46+ ILC3s.