ITK and graft versus host disease: To determine whether CD4+ T cell-intrinsic ITK signaling might be sufficient to induce GVHD, we repeated the same experiments using purified CD4+ T cells from either WT or Itk-/- mice in the MHC-mismatch mouse model of allo-HSCT (B6→BALB/c) (Supplementary Figures 1A–C).