Hematologic recovery after autologous PBPC transplantation: importance of the number of postthaw CD34+ cells

BACKGROUND: The implementation of a quality-assurance program is a major requirement to ensure quality and safety of the final PBPC components intended for clinical use. It is not clear whether the quantification of CFU-GM and CD34+ cells should be done on fresh components and after cryopreservation, which better represents the actual composition of the graft. STUDY DESIGN AND METHODS: Correlation between prefreeze and postthaw MNCs, CD34+ cells, and CFU-GM collected from 126 patients undergoing BMT (n=43) or PBPC (n =83) transplantation were evaluated. The statistical incidence of prefreeze and postthaw parameters as well as patient characteristics and conditioning regimens on hematologic recovery were analyzed. RESULTS: By multivariate analysis, prefreeze and postthaw CD34+ cells were the only two variables significantly and independently correlated to hematologic recovery. Low prefreeze and postthaw CD34+ cell numbers associated to a low CD34+ yield characterize PBPC grafts from patients who have the slowest hematologic recovery. The postthaw PBPC CD34+ cell number can be estimated before conditioning regimen by thawing a small aliquot of the graft. CONCLUSION: In association to prefreeze CD34+ cell number and to CD34+ yield, postthaw CD34+ cell number may be useful in monitoring cell loss during processing and identifying patients at risk of slow PBPC engraftment.