There have been four published studies [15, 19–21] of donor-derived anti CD19 CAR-T therapy with three studies using a CD28 costimulatory domain and one with a 41BB co-stimulatory domain including one study where donor-derived multi-virus specific T-cells were transduced with a CD19-CAR28z construct to prevent and treat viral infection and relapse after allo-HCT [21]. Here, CD19 is linked to viral infectious disease.