IL6 and graft versus host disease: Both the B6 Villin-KO and the B6 WT allo-recipients also demonstrated similar numbers of IFN-γ–producing CD4+ T cells (Supplemental Figure 1G) and serum cytokine levels of proinflammatory systemic cytokines that have been implicated in GVHD severity, such as IFN-γ, TNF-α, or IL-6 (Figure 1H).