In vivo expanded NK cells were functional after Hi-Cy/Flu. PBMCs were collected 14 days after haploidentical cell infusions from the patient shown in Figure 2. (A) 92% of all circulating cells were CD56⁺/CD3^– NK cells corresponding to an absolute circulating NK-cell count of 650/μL. (B) Fresh day-14 samples were tested without further activation in a standard 4-hour chromium release assay demonstrating cytotoxicity against K562. • indicates K562; ○, Raji.