rhIL-15 promotes donor chimerism 14 days after haplo-NK-cell infusion with highly functional donor NK cells. (A) Percentages of peripheral blood NK-cell detectable donor chimerism at days 7 and 14 in the IV and SC rhIL-15 cohorts. (B) Cytotoxicity of K562 cells was measured using NK cells isolated from peripheral blood mononuclear cells at day 14 after haplo-NK-cell infusion from patients who successfully in vivo expanded donor NK cells vs nonexpanders. Cytotoxicity was similar in IV or SC IL-15–stimulated NK cells (not shown).