Based on an initial HLA-A*02:01–specific CAR derived from the ScFv of a mouse monoclonal antibody against human HLA-A*02 [10], a panel of humanized HLA-A*02 CARs was developed and tested in Tregs for their ability to suppress xenogeneic graft-versus-host disease (GvHD) and rejection of human skin allografts in immunocompromised mice [7–9]. This evidence concerns the gene HLA-A and graft versus host disease.