Early and long-term engraftment after autologous peripheral stem cell transplantation in acute myeloid leukemia patients.

This study aimed to identify which subset of CD34+ cells might be the most predictive of early and long-term hematopoietic recovery following autologous peripheral blood stem cell (PBSC) transplantation (PBSCT) in adult acute myeloid leukemia (AML) patients. The relationships between the number of 'mature' subsets of CD34+ cells (CD34+/CD33+, CD34+/CD38+, CD34+/DR+ and CD34+/CD90-) and 'immature' subsets of CD34+ cells (CD34+/CD33-, CD34+/CD38-, CD34+/DR- and CD34+/CD90+) and early and long-term hemoglobin, neutrophil and platelet counts were studied in a homogeneous series (for disease, pre-transplant chemotherapy, mobilization chemotherapy, conditioning regimen) of 26 AML patients after autologous PBSCT. Cell counts were performed before and after cryopreservation, but only after thawing were the cell counts used for correlation with early and long-term engraftment. The number of CD34+/CD38- cells infused correlated with the neutrophil (r = 0.88, p < 0.005) and platelet counts (r = 0.67, p < 0.05) at 12 months after PBSCT. This correlation was better than that for the total CD34+ cell dose at 12 months (r = 0.36, p = 0.09 for neutrophil count and r = 0.48, p = 0.06 for platelets count). The number of CD34+/CD90+ cells was also correlated with the platelet counts at 6 (r = 0.70, p < 0.05) and 12 months (r = 0.80, p = 0.005) after PBSCT. This correlation was better than the total dose of CD34+ cells at 6 (r = 0.31, p = 0.3) and 12 months (r = 0.48, p = 0.06) for the platelet counts. CD34+ subset analysis suggests that for early engraftment the total number of CD34+ cells infused is more strongly correlated than the CD34+ subsets, whereas the CD34+/CD38- and CD34+/CD90+ subsets may be associated with sustained long-term neutrophil and platelet engraftment. These findings may help to predict the repopulating capacity of PBSCs in AML patients after autologous PBSCT, especially when a relatively low number of CD34+ cells is infused.