There are several possible explanations: First, the widely used immunization protocol utilizing MOG/CFA for induction of EAE might be an inappropriate trigger for ILCs. Second, the overwhelming amount of activated, MOG-reactive T cells PI3K inhibitor might mask a possibly subtle role of ILCs during the course of autoimmunity. Third, ILCs do not play an important role in this particular setting of autoimmune inflammation. In summary, we identified a CNS-invading population of group 3 ILCs with the capacity to secrete cytokines locally. However, using a functional depletion model

targeting all Thy1+ ILC subsets, we have thoroughly ruled out the involvement of ILCs in the pathogenesis of EAE. Nevertheless, since the initial trigger for human MS is still unknown, it cannot be excluded that ILCs participate in this primary event. Lastly, even though the precise function and cellular targets of IL-23 remain elusive, we can herewith exclude a vital role of ILCs as pathologically relevant responders to IL-23 during autoimmune neuroinflammmation. C57BL/6 (WT), congenic C57BL/6 Thy1.1, Rag1−/−, TCRβδ−/− mice as well as Rorc-GFP mice were purchased from Jackson Laboratories and bred in-house under specific pathogen-free conditions. Rorc-GFP mice

were only used as heterozygous reporter animals. Rorc-Cre and R26-YFPSTOPflox mice were obtained from Andreas Diefenbach and bred in-house either on a WT or a Rag−/− background. EAE was induced as described GDC-0068 mw previously [36]. Briefly, mice were immunized subcutaneously with 200 μg of MOG35–55 peptide (MEVGWYRSPFS-RVVHLYRNGK; GenScript) emulsified in CFA (Difco) and L-NAME HCl two intraperitoneal injections of 200 ng pertussis toxin (Sigma) on day 0 and 2. For passive EAE experiments, spleen and LN cells

were harvested from C57BL/6 Thy1.1 donor mice on day 7 after immunization, restimulated 2 days with 20 μg/mL MOG and 10 ng/mL IL-23, and then i.v. transferred to Rag1−/− recipients. All animal experiments were approved by local authorities (Swiss veterinary office, canton Zurich, licence 55/2009 and 85/2012). Depleting antibodies used in some experiments (rat-anti-mouse-Thy1.2, clone 30H12 and isotype control ratIgG2b, clone LTF-2) were obtained from BioXCell (West Lebanon, USA). For peak disease analysis, animals were euthanasized on days 13–16 postimmunization. Mononucleated cells were obtained from CNS tissues as described [36]: mice were euthanized using CO2 inhalation. Afterwards, animals were perfused using ice-cold PBS and brain and spinal cord were collected. Tissues were cut into small pieces using scissors, followed by 30 min of digestion with 0.4 mg/mL collagenase D (Roche) and 0.5 mg/mL DNAse (Sigma) in IMDM containing 25 mM HEPES and 2% FCS. Remaining pieces of tissue were homogenized using syringes and 20 gauge needles.