CD4 and Arthritis: To assess the contribution of GM-CSF from either stromal cells or ILCs to autoimmune arthritis, we x-irradiated (6Gy) Rag2−/− or Csf2−/−Rag2−/− mice, reconstituted the mice with Rag2−/− or Csf2−/−Rag2−/− BM cells, transferred to them Csf2−/− SKG CD4+ T cells 6 weeks after BM reconstitution, and assessed arthritis score 12 weeks after CD4+ T cell transfer (Figure 5A).