Quantifying loss of CD34+ cells collected by apheresis after processing for freezing and post-thaw.

INTRODUCTION: CD34(+) cells collected for autologous bone marrow transplantation (BMT) are usually quantified in the apheresis product after collection, but the necessity to repeat these measures post-thaw is controversial. METHODS: We examined the loss of CD34(+) cells after collection, preparation for freezing and post-thaw in apheresis products collected for BMT. RESULTS: Median number of CD34(+) cells collected per unit was 1.61×10(6)/kg, viability: 97-100%. This number decreased to 1.38×10(6)/kg, viability: 96-100% before freezing and was 1.17×10(6)/kg post-thaw. Viability decreased to 86-98%. The relative loss of viable PBHPC showed an inverse correlation with the ratio "CD34(+) cells/total nucleated cells" (r=-0.45; p=<0.0005). This relative loss was largest in patients with Hodgkin's lymphoma. CONCLUSION: Cryopreservation and thawing of PBHPCs in leukapheresis products provokes a small but significant stem cell loss. So, quantification of viable CD34(+) cells post-thaw is important, especially in poorly mobilizing patients. Besides, the ratio "CD34(+) cells/total nucleated cells" after leukapheresis is an important parameter for prediction of neutrophil recovery after BMT.