Several labs simultaneously reported a population of mouse cells expressing NKp46 (also known as a natural cytotoxicity receptor or NCR) that did not resemble normal NK cells. These cells did not produce perforin, granzymes, IFN-γ, or TNF. However, they did make IL-22 and expressed RORγt. Collectively, these NKp46, RORγt positive cells have had many names, including NCR22 cells, NKp46 ILCs, ILC22s, and NKR-Lti cells. To make things easier, it is now recommended they be called Group 3 ILCs. Further investigation will be needed to clarify ILC3 subsets and the plasticity of these cells (see ILC1 cells).
NCR+ ILC3s are a subclass of cells typically found in mucosal tissue like the intestinal tract, interacting with microbiota. LTi (lymphoid tissue inducer) cells are a subset of group 3 ILCs primarily involved with secondary lymphoid organ formation during embryogenesis. They are capable of making IL-17A and IL-22 after stimulation. Finally, in a mouse model of (Rag-/-mice infected with Helicobacter hepaticus), another cell subset lacks NCR (e.g., NKp46) expression, but secretes IFN-γ, IL-17A, and IL-22. Termed NCR- ILC3s, they were found to be pathological in the innate mouse model.