Humanised mouse models of GVHD, in which human peripheral blood mononuclear cells (PBMCs) are injected into immunodeficient mice, most commonly NOD.Cg-Prkdcscid Il2rgtm1Wjl (NSG) mice, are a valuable pre-clinical model to test and explore the efficacy of existing and emerging GVHD therapies [20]. Here, CTSG is linked to graft versus host disease.