Experimental outline. IL-7 was injected intravenously into HSC-humanized NSG mice before 2x106 t.u. of CD8-LVCD19CAR (CAR), or PBS as control (PBS), were administered. Distinct symbols for each individual animal are used throughout B-F (M16: lilac triangle; M19: blue triangle). Open symbols indicate animals from the vector-injected group devoid of PCR-detectable CAR T cells. 