Ror t+ Innate Lymphoid Cells in Intestinal Homeostasis and Immunity

Innate lymphoid cells (ILC) combine innate and adaptive immune functions and are part of the first line of defense against mucosal infections. ILC are set apart from adaptive lymphocytes by their independence on RAG genes and the resulting absence of specific antigen receptors. In this review, we will discuss the biology and function of intestinal ILC that express the nuclear hormone receptor Ror t (encoded by the Rorc gene) and highlight their role in intestinal homeostasis and immunity. Copyright © 2011 S. Karger AG, Basel Ror t+ Innate Lymphoid Cells Expression of Ror t delineates a heterogeneous group of ILC that depend on RORC and the helix-loop-helix protein ID2 for their development [1–7] . Ror t+ ILC have a variety of phenotypes that might represent either activation states or progressive developmental intermediates of one cell lineage, or distinct lineages of Ror t+ ILC that share a common precursor. In the fetal murine intestine the predominant ILC population is characterized by expression of CD117 (ckit) and CD127 (IL7R ) [8, 9] . The majority of these Ror t+ ILC express CD4 and were previously termed lymphoid tissue inducer (LTi) cells because of their Received: March 29, 2011 Accepted after revision: June 27, 2011 Published online: September 5, 2011 Journal of Innate Immunity Dr. T. Cupedo Department of Hematology, Room Ee1330f Erasmus University Medical Center PO Box 2040, NL–3000 CA Rotterdam (The Netherlands) Tel. +31 10 704 4082, E-Mail t.cupedo @ erasmusmc.nl © 2011 S. Karger AG, Basel 1662–811X/11/0036–0577$38.00/0 Accessible online at: www.karger.com/jin D ow nl oa de d by : 54 .7 0. 40 .1 1 11 /1 9/ 20 17 3 :1 0: 50 P M