Antileukemia effect of autologous, HLA-matched and -mismatched CD56⁺ cells. (A) CML CFU-GM colony inhibition by IL-2–activated HLA-identical donor CD56⁺ cells at different effector-to-target ratios (patient 15). (B) Cytotoxicity (Calcein-AM release) of HLA-matched sibling transplant donor (•), recipient after transplantation (○), mother (▪), and father (□) CD56⁺ cells on CD34⁺-CML recipient cells (patient 3).