Yotam E Bar-Ephraim, Jasper J Koning, Estefany Burniol Ruiz, Tanja Konijn, Vera P Mourits, Kim A Lakeman, Louis Boon, Marijn Bögels, J Peter van Maanen, Joke M M Den Haan, Marjolein van Egmond, Gerd Bouma, Rogier M Reijmers, Reina E Mebius
Innate lymphoid cells (ILCs) guard epithelial tissue integrity during homeostasis, but can be potent immune effector cells during inflammation. Precursors to all ILC subsets (ILC precursors [ILCP]) have been identified in human peripheral blood (PB). We found that during homeostasis, ILCP in PB of mouse and human expressed homing receptors for secondary lymphoid organs, mainly CD62L. These ILCP entered mouse lymph nodes in a CD62L-dependent way and relied on S1P receptors for their exit. Importantly, CD62L expression was absent on human ILCs expressing NKp44 in tonsils and PB of Crohn disease patients, and relatively fewer CD62L+ ILCP were present in PB of Crohn disease patients...
November 30, 2018: Journal of Immunology: Official Journal of the American Association of Immunologists