Progenitor cell subsets and engraftment kinetics in children undergoing autologous peripheral blood stem cell transplantation

The main objective of the present study was to determine the role of CD34(+) cell subsets in the haemopoietic recovery of children undergoing peripheral blood stem cell transplantation. For this purpose, 38 leukaphereses from 33 children with malignancies mobilized with G-CSF were analysed. Using dual-colour flow cytometry, different subpopulations of CD34(+) cells were quantified and the number of each reinfused subsets correlated with haemopoietic resurgence. Multivariate analysis showed that the number of CD34(+)CD38(-) cells and CD34(+)CD38(+) cells correlated better with time to neutrophil and platelet recovery respectively, than the total number of CD34(+) cells. Threshold values for rapid haemopoietic recovery, determined by the receiver operating characteristic analysis, were found to be 0.5 x 10(6) CD34(+) CD38(-) cells for neutrophil engraftment, and 2.0 x 10(6) CD34(+) CD38(+) cells for platelet recovery It is suggested that the analysis of CD34(+) cell subsets could increase understanding of the repopulation capacity of a given leukapheresis product in peripheral blood stem cell transplantation procedures in children. In particular, this procedure could be extremely useful when low numbers of CD34(+) cells are collected.