Human IL-25- and IL-33-responsive type 2 innate lymphoid cells are defined by expression of CRTH2 and CD161

Mice have lineage-negative IL-7Rα+ (innate lymphoid) cells that contribute to type 2 immunity. Spits and colleagues identify a similar CRTH2+CD161+ population in human lungs and gut that produces IL-13 after stimulation. Innate lymphoid cells (ILCs) are emerging as a family of effectors and regulators of innate immunity and tissue remodeling. Interleukin 22 (IL-22)- and IL-17-producing ILCs, which depend on the transcription factor RORγt, express CD127 (IL-7 receptor α-chain) and the natural killer cell marker CD161. Here we describe another lineage-negative CD127+CD161+ ILC population found in humans that expressed the chemoattractant receptor CRTH2. These cells responded in vitro to IL-2 plus IL-25 and IL-33…