Association of bone marrow natural killer cell dose with neutrophil recovery and chronic graft-versus-host disease after HLA identical sibling bone marrow transplants.

Allogeneic bone marrow (BM) transplant (BMT) outcomes have been correlated with the infused nucleated, CD34(+), and T- cell dose. The potential impact of natural killer (NK) BM infused cell dose has however not been established. We analysed the outcomes of 78 patients receiving an HLA identical BMT. A higher NK cell dose was associated with the speed of neutrophil (P = 0.05) and platelet recovery (P = 0.04). Higher nucleated cells, CD34(+), CD3(+), CD3(+)/4(+), CD3(+)/8(+) and NK cell dose were associated with a lower incidence of chronic GvHD (cGvHD) in univariate analysis. In multivariate analysis, the risk of cGvHD was increased by a lower NK cell dose [hazard ratio (HR) = 2.3 (1.2-4.4) for cell dose <0.9 x 10(6)/kg; P = 0.01] and an older age [HR = 1.4 /10 years (1.1-1.8); P = 0.002]. In addition, a higher CD3(+)/4(+) and NK cell dose were associated with a decreased incidence of viral infections (P = 0.03 and P = 0.06 respectively). No specific cell subpopulation infused dose was associated with survival. In conclusion, a higher BM NK cell dose is associated with an increased speed of neutrophil recovery and a decreased incidence of cGvHD.