Post-Transplantation Natural Killer Cell Count: A Predictor of Acute Graft-Versus-Host Disease and Survival Outcomes After Allogeneic Hematopoietic Stem Cell Transplantation.

Abstract Background Reconstitution of the immune system after allogeneic hematopoietic stem cell transplantation (allo-HSCT) plays an important role in post-transplant outcomes. However, the clinical relevance of the lymphocyte subset (LST) counts to transplant-related complications and survival outcomes after allo-HSCT has not been fully elucidated. Patients and Methods A total of 70 patients who had undergone allo-HSCT from 2007 to 2013, with LST results both 7 days before conditioning and 30 or 90 days after allo-HSCT were included. The LST counts in the peripheral blood were determined using 6-color flow cytometry. Clinical information, including transplant-related events during the first 100 days after allo-HSCT, was reviewed, and any association between these events and LST was analyzed. Results At 30 days after allo-HSCT, the CD4 + T-cell ( P  = .009) and B-cell ( P  = .035) counts were lower and the natural killer (NK) cell count was greater ( P + T-cell ( P  = .001) and NK cell ( P P  = .043 and P  = .028, respectively) and greater nonrelapse mortality ( P  = .036 and P  = .033, respectively). A low NK cell count on day 30 was still prognostic for overall survival ( P  = .039) on multivariable analysis. Conclusion NK cell counts after allo-HSCT, especially on day 30, were predictive of acute graft-versus-host disease, nonrelapse mortality, and survival. Serial lymphocyte subset analysis can be used to identify and treat patients at risk during the early period after allo-HSCT.