Transplantation with higher dose of natural killer cells associated with better outcomes in terms of non‐relapse mortality and infectious events after allogeneic peripheral blood stem cell transplantation from HLA‐matched sibling donors

BACKGROUND: Little is known about the role of the CD56+ natural killer (NK) cell dose on the outcome of allogeneic peripheral blood stem cell transplantation (PBSCT). Recently, higher dose of NK cells has been associated with a lower incidence of severe graft-versus-host disease (GVHD). The current study attempted to evaluate the effect of the NK cell dose on transplant outcomes in allogeneic PBSCT setting. METHODS AND MATERIALS: Sixty-one cytokine mobilized PBSC recipients were analyzed according to the infused dose of CD34+ cells and NK cells in relation to overall survival (OS), non-relapse mortality (NRM), GVHD, and infectious events. RESULTS: The group received a higher dose of NK cells (> or =5 x 10(7)/kg) showed a lower incidence of NRM (P = 0.0186) and infectious events (P = 0.0107). In a multivariate analysis, a higher dose of NK cells was correlated to better transplant outcomes for NRM (P = 0.042) with CD34+ cell dose (P = 0.018), and for infectious events (P = 0.013) with CD34+ cell dose (P = 0.016). Higher NK cell infusion group also showed a faster immune recovery in serial measurements at days +90, +180, and +365. CONCLUSIONS: High dose of NK cells may play an important role in improving transplant outcomes, in terms of reducing NRM and infectious events together with CD34+ cells.