Figure 1.

Characteristic of ILCs. ILCs encompass NK, ILC1, ILC2, and ILC3 cells. Murine and human NK cells can secrete IFN-γ, granzyme B, and perforin. In humans, NK cells have two main subsets: CD3⁻CD56^brightCD16⁻ and CD3⁻CD56^dimCD16⁺ cells. ILC1 cells can respond to IL-12 and IL-15, and subsequently produce IFN-γ and TNF-α. In humans, CD127⁺CD161⁺ CD34⁻ c-Kit⁻T-bet⁺ Eomes⁻ IFN-γ⁺ ILC1 cells are enriched in the tonsils. Additionally, Lin⁻CD127⁺CD161⁺ CD117⁻ NKp44⁻CRTH2⁻ ILC1 cells have been found in the human PBMCs. In mice, ILC2 cells are Lin⁻CD127⁺CD25⁺ KLRG1⁺ GATA3^high cells which are responsive to IL-2, IL-4, IL-7, IL-25, IL-33, TSLP, and prostaglandin D2, and subsequently produce multiple effector cytokines. In humans, ILC2 cells express GATA3, CD127, CD161, CD25, ST-2, IL-17A, and CRTH2. Both murine and human ILC3 cells are Lin⁻CD127⁺RORγt⁺. They are responsive to IL-1β, IL-6, and IL-23, and produce IL-22, IL-17A, IL-17F, GM-CSF, TNF-α, and LTα₁β₂.