Since the anti-Orai1 mAb does not cross-react with rodent Orai1 (data not shown), we chose to use a mouse model of Graft-Versus-Host Disease (GvHD) in which human PBMCs are transferred into immunodeficient NOD.scid.IL-2Rγc−/− mice, hereafter referred to as the humanized GvHD model [29], [30]. Here, ORAI1 is linked to graft versus host disease.