As cross-reactivity to HLA-A*69 could not be assessed, subjects carrying this specific HLA-A allele will be excluded from the clinical trial.Humanized mouse models are well established tools to study human Treg function in vivo and have been used to successfully investigate their role in prevention of xenogeneic GvHD [32] and rejection of various xenografts such as skin, islets, and arteries [33]. Here, HLA-A is linked to graft versus host disease.