Figure 1.

Critical transcription factors regulate ILC development. After the stage of common lymphoid progenitor (CLP), transcription factors such as TCF1, TOX and Nfil3, together with the Notch signals, promote the generation of an early innate lymphoid progenitor (EILP) expressing Integrin α₄β₇. EILP has the potential to become both the helper-like innate lymphoid cell (ILC) lineage and the cytotoxic conventional nature killer (cNK) lineage, but has lost the capacity to generate T cells, B cells or dendritic cells. GATA-3 is required for the development of common helper-liker innate lymphoid progenitor (ChILP), which expresses high levels of DNA binding inhibitor Id2. The development of the cytotoxic innate lineage does not require GATA-3, but require Id2 whose expression level is low at the progenitor stage and gradually increases during NK cell development. Within the ChILP population, some cells transiently express PLZF and are committed to non-LTi ILC lineages in a GATA-3-dependent manner. Progenitors that have not previously expressed PLZF generate the LTi cells in a RORγt-dependent manner