Implications of CD34+ cell dose on clinical and haematological outcome of allo-SCT for acquired aplastic anaemia.

The precise effects of CD34+ cell dose on the outcome of allogeneic transplantation for aplastic anaemia (AA) are not known. Previous studies have used the total mononuclear cell count to quantify stem cell dose. We evaluated the effects of CD34+ cell dose on the clinical and haematological end points of transplantation. The transplant variables and outcome parameters on 46 patients with acquired AA were assessed by comparing low vs high CD34+ cell doses. Infusion of less than 2 x 10(6)/kg of CD34+ cells was associated with an increased incidence of graft failures (P=0.03), higher incidence of bacterial infections (P=0.006) and a delay in the engraftment of neutrophils (P=0.046). The latter was found to be an effect of stem cell source (non-PBSC) rather than the CD34+ count. Other parameters, such as plt engraftment (P=0.63), red cell (P=0.94) and plt (P=0.31) transfusion independence, chimerism, acute and chronic GVHD (P=1.0) and OS (P=0.57), were not significantly influenced by the CD34+ cell dose. These findings are different to the published studies on the relevance of CD34+ cell dose in allogeneic transplantation for haematological cancers.