Figure 1.

Cytokines involved in mouse and human innate lymphoid cells (ILCs) development. All ILCs are derived from a common lymphoid progenitor (CLP). In the mouse, interleukin (IL)-7 is essential for the development of ILC2, ILC3, and lymphoid tissue inducer (LTi) cells, and IL-15 is required for development of natural killer (NK) cells. IL-15 is important for ILC1 development but some ILC1 can develop independent of IL-15. For humans, IL-7 and IL-15 also play an important role in ILC and NK-cell development, and some studies indicate the involvement of IL-1β as, thus far, identified ILC progenitors (ILCPs) all express its receptor. α-LP, α-Lymphoid progenitor; EILP, early innate lymphoid progenitor; CHILP, common helper-like ILC progenitor; PLZF, promyelocytic leukemia zinc-finger protein; NKp, NK progenitor; cNK, conventional NK.