Systemic human ILC precursors provide a substrate for tissue ILC differentiation

Innate lymphoid cells (ILC) represent innate versions of T helper and cytotoxic T cells that differentiate from committed ILC precursors (ILCP). Still, how ILCP relate to mature tissue-resident ILCs remains unclear. We observed that a population of CD117+ ILC from peripheral blood (PB) of healthy donors does not represent any conical ILC subset, but expressed marker (CD117) commonly expressed by hemato-lymphoid progenitors. We therefore hypothesized PB CD117+ ILC might include uncommitted lymphoid precursors. In order to further understand the identity of PB CD117+ ILC, we profiled the transcriptome of highly purified circulating CD117+ ILC compared to CD34+ HSC, the latter representing immature hematopoietic progenitors with multi-lineage potential. Clear differences in gene expression profiles emerged, with a large cluster of 1540 genes expressed at substantially higher levels in CD117+ ILC. In contrast, CD34+ HSC cells highly expressed genes involved in the broad development of diverse hematopoietic lineages. Compared to HSC, CD117+ ILC express high levels of TF that have been shown to be essential for murine ILC development and we did not detect transcripts characteristic of T and B cells development. Transcriptomic analysis suggested that CD117+ ILC represent lymphoid-biased progenitors carrying a TF expression profile resembling a multi-potent ILC precursor (ILCP). Overall design: CD117+ ILC and CD34+ HSC were freshly isolated by FACS of peripheral blood of two healthy adult individuals. In total, 4 samples were analyzed and comparing between two cell populations.

4

Lim AI, Li Y, Lopez-Lastra S, Stadhouders R, Paul F, Casrouge A, Serafini N, Puel A, Bustamante J, Surace L, Masse-Ranson G, David E, Strick-Marchand H, Le Bourhis L, Cocchi R, Topazio D, Graziano P, Muscarella LA, Rogge L, Norel X, Sallenave JM, Allez M, Graf T, Hendriks RW, Casanova JL, Amit I, Yssel H, Di Santo JP