Lineage Relationship Analysis of RORγt+ Innate Lymphoid Cells

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Science  23 Sep 2010:
DOI: 10.1126/science.1194597


Lymphoid tissue inducer (LTi) cells initiate the development of lymphoid tissues through the activation of local stromal cells in a process similar to inflammation. LTi cells express the nuclear hormone receptor RORγt, which also directs the expression of the proinflammatory cytokine interleukin-17 in T cells. We show here that LTi cells are part of a larger family of proinflammatory RORγt+ innate lymphoid cells (ILCs) that differentiate from distinct fetal liver RORγt+ precursors. The fate of RORγt+ ILCs is determined by mouse age, and after birth, favors the generation of cells involved in intestinal homeostasis and defense. Contrary to RORγt+ T cells, however, RORγt+ ILCs develop in the absence of microbiota. Our study indicates that RORγt+ ILCs evolve to pre­empt intestinal colonization by microbial symbionts.