Figure 1.

Development and the main features of ILC subsets. ILCs are derived from common lymphoid progenitors (CLPs) found within fetal liver and adult bone marrow. Dedicated TFs restrain B and T cell fates but guide the development of different ILC subsets. CLPs develop into common lymphoid progenitors (CILPs); then, through a series of transcriptional regulation processes, CILPs differentiate into natural killer cell precursor (NKPs) or common helper innate lymphoid progenitor (CHILPs), and the latter give rise to innate lymphoid cell precursor (ILCPs) and lymphoid tissue inducer progenitor (LTiPs). Each kind of precursor cell involves a branch in the ILC family. Based on the differential development trajectories and functions, the ILC family is categorized into five groups: NK cells, ILC1s, ILC2s, ILC3s and LTi cells. Each ILC subset secretes different effector cytokines that promote important physiological or pathological reactions.