Human RORγt+ CD34+ cells are lineage-specified progenitors of group 3 RORγt+ innate lymphoid cells

Group 3 innate lymphoid cells (ILC3) are defined by the expression of RORγt, which is selectively required for their development. The lineage-specified progenitor cells of human ILC3 and their developmental site after birth remain undefined. Here we identified a novel population of human CD34+ hematopoietic progenitor cells (HPC) expressing RORγt and sharing with ILC3 a distinct transcriptional signature. RORγt+ CD34+ HPC were located in tonsils and intestinal lamina propria (LP) and selectively differentiated towards ILC3. Conversely, RORγt- CD34+ HPC displayed commitment potential for both ILC3 and NK cells and the differentiation fate towards these two cell lineages was determined by cytokine and aryl hydrocarbon receptor (AhR) signaling. Thus, we propose that RORγt+ CD34+ cells represent human lineage-specified progenitors of IL-22+ ILC3 and that tonsils as well as intestinal LP might be preferential sites of their differentiation. ILC3, NK cells and the CD34+ HPC subsets were sorted from tonsils of 6 distinct donors to purity above 95%. cRNA of the sorted cell populations was hybridized to an Agilent Whole Human Genome Oligo Microarrays (8x60K v2, Design ID 039494)