CD4 and graft versus host disease: Given the requirement for donor T cells in the induction of GVHD-induced neuroinflammation, we examined the role of CB2R expression on donor T cells and noted that absence of CB2R expression resulted in a significant decrease in the percentage and absolute number of donor-derived CD4+, but not CD8+, T cells in GVHD mice (Supplemental Figure 4B).