IL15 and post-transplant lymphoproliferative disease: This study provides novel evidence that NKG2D CAR-T exerts anti-tumor and anti-viral activities in treating EBV-PTLD, and IL-15/IL-15Rα improves the therapeutic and safety effects by increasing the proportion of TCM, promoting T cell homing in spleen and bone marrow and multiple synergistical cytokine regulation.