Documented IL-6 signaling is critical to induce donor type-17 T (Th17) and type 22 T (Th22) cell differentiation after bone marrow transplantation (BMT) (59–61), and the anti-IL-6 receptor monoclonal antibody, tocilizumab, has been shown to effectively reduce the incidence of acute GVHD (62). This evidence concerns the gene IL6 and acute graft versus host disease.