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.