Blast counts in blood progenitor cell (BPC) collections correlate with CD34⁺ cells and CFU-GM and are a useful predictor of haemopoietic recovery after autologous BPC transplantation

Abstract

Assessment of the quality of blood progenitor cell (BPC) collections is based mainly on CD34⁺ cell enumeration by flow cytometry, or scoring of granulocyte–macrophage colony-forming cells (CFU-GM). A minimum cell dose for haemopoietic recovery can be defined by both assays; however, the CFU-GM assay can not be used for ‘real-time’ decisions, whereas CD34⁺ cell scoring requires facilities and expertise which are not universally available. We have investigated the possibility of using morphologically defined blast cells within BPC harvests as a surrogate marker of harvest haemopoietic stem/progenitor cell content, as well as their correlation with CD34⁺ cells and CFU-GM within the harvests. We have found that blast counts correlate strongly with both CD34⁺ cell counts and CFU-GM within BPC harvests, as well as with time to granulocyte and platelet recovery after autologous BPC transplantation (ABPCT). Furthermore, we have defined a threshold value of 1.3 × 10⁶/kg blasts, above which there is a high probability of rapid haemopoietic recovery after ABPCT. We conclude that blast count is a simple, rapid and reliable method of assessing BPC harvest quality.