CD19 and neoplasm: Different PB-NK subsets, such as NKG2A−KIR−, NKG2A+KIR−, NKG2A+KIR+, and NKG2A−KIR+NK cell subsets, that have been transduced with the retroviral CD19-CAR vector show stable similar expression levels of CAR, which enhance in vitro NK cytotoxicity against CD19+ tumor cell lines.