Phenotypical and functional analysis of donor lymphocyte infusion products after long-term cryopreservation

Donor lymphocyte infusions, collected from peripheral blood by apheresis, are regularly used to re-establishing disease control in patients with impending or full relapse after allogeneic cell transplantation. The cryopreservation and thawing processes of the cellular products, required for clinical needs, result in a decreased cellular recovery. The aim of this study was to perform an integral analysis of phenotypic and functional characteristics in different cell populations, within cryopreserved products used for therapeutic purposes. A total of 77 cryopreserved products were analysed. Cell viability and subpopulations such as CD3, CD4, CD8, CD14 and CD56 cells were quantified by FACS. Cell proliferation, cytotoxic capacity and CD4 intracellular ATP content were evaluated. A significant loss of cell viability was observed. CD56 cells were significantly reduced when compared with mononuclear cells without cryopreservation. Cell proliferation was also significantly reduced in the cryopreserved products. Cytotoxic capacity was decreased as well although it did not reach statistical significance. However, CD4 intracellular ATP was increased in the cryopreserved products. The analysed functional cell properties showed a wide distribution range although the apheresis, cryopreservation and thawing procedures were similar in all the analysed samples. Our findings may be useful for an improved characterisation of cryopreserved products to be used as donor lymphocyte infusion for therapeutic purposes.