CD56^dimNK cells within the stem cell product are the major contributing factor to the association with disease relapse risk. Relationship between the number of CD56^bright and CD56^dim NK cells administered within the stem cell infusion and RI. The median dose of both subsets was defined, and transplants were divided into those where the infusion contained a cell dose either above (blue) or below this median (red) value (A). The cohort was then split into patients who relapsed or not within 2 years posttransplant to assess absolute number (n = 100), dose (n = 100), and percentage (n = 107) of all NK cells within the stem cell product (B). This was also shown in CD56^bright and CD56^dim NK cells (n = 100) (C). All NK groups proved to be significantly reduced in relapse patients.