GVHD prevention in recipients given STAT3–/– T cells was evident with lower serum concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), soluble suppression of tumorigenicity 2 (sST2), and IFN-γ, although only slightly lower TNF-α concentrations (Figure 1, B and C) compared with that of recipients given WT T cells. Here, TNF is linked to graft versus host disease.