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 (≥ 5 × 10⁷/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.