Variable resistance to freezing and thawing of CD34-positive stem cells and lymphocyte subpopulations in leukapheresis products

Abstract Background aims Leukapheresis products for hematopoietic stem cell transplantation can be cryopreserved for various indications. Although it is known that CD34 + cells tolerate cryopreservation well, a significant loss of CD3 + cells has been observed, which has been ascribed to several factors, including transport, storage conditions and granulocyte-colony stimulating factor (G-CSF) administration. Methods To assess the tolerance of CD34 + cells and lymphocyte subpopulations for cryopreservation and thawing, the post-thaw recoveries of CD34 + cells, CD3 + CD4 + cells, CD3 + CD8 + cells, CD19 + cells and CD16 + CD56 + cells were determined in 90 cryopreserved apheresis products, among which 65 were from G-CSF–mobilized donors, and 34 from unrelated donors that underwent transport before cryopreservation at our center. A controlled rate freezer and 5% dimethyl sulfoxide were used for cryopreservation. Results We could detect statistically significant differences for CD34 + cell recovery (93.0 ± 20.7%) when compared to CD3 + CD4 + cell (83.1 ± 15.4%, P  = 0.014), and CD3 + CD8 + cell recovery (83.3 ± 13.9%, P  = 0.001). Similarly, CD19 + cell recovery (98.6 ± 15.1%) was higher than CD3 + CD4 + cell ( P  = 2.5 × 10 −7 ) and CD3 + CD8 + cell recovery ( P  = 1.2 × 10 −8 ). Post-thaw recovery rates of all cell populations were not impaired in G-CSF–mobilized products compared with non-mobilized products nor in unrelated compared with related donor products. Discussion Our data suggest a lower tolerance of CD3 + cells for cryopreservation and demonstrate that freezing–thawing resistance thawing is cell-specific and independent from other factors that affect post-thaw recovery of cryopreserved cells. Thus, a clinical consequence may be the monitoring of post-thaw CD3 + cell doses of cryopreserved products, such as donor lymphocyte infusions.