The state of T cells before cryopreservation: Effects on post-thaw proliferation and function.

Aim: We aim to assess the effect of the state of T cells before cryopreservation on the post-thaw proliferative capacity, phenotype and functional response.

Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from a hepatocellular carcinoma (HCC) patient, and the T cells were frozen during cell culture according to our experimental design. After a period of re-culture, the proliferative capacity of the cryopreserved cells, the expression of T cell surface markers and the secretion of IFN-γ and IL-10 were assayed.

Results: There was >90% cell viability after thaw in every group. Lymphocytes cryopreserved at day 4, 8 or 12 during the cell culture were allowed to recover for 24 h, whereas lymphocytes cryopreserved while freshly isolated were allowed to recover for 72 h. After the period of re-culture, cryopreservation at day 4, 8 or 12 during T cell culture was not found to alter the T cell subpopulation. The proportions of NKT and Treg cells were unchanged when cells were cryopreserved at day 12 during T cell culture. IFN-γ secretion was not impacted by cryopreservation, and IL-10 secretion was significantly decreased when cells were cryopreserved at day 8 or 12 during T cell culture.

Conclusion: The state of T cells before cryopreservation has effects on the post-thaw proliferation capacity, the phenotype and the secretion of IFN-γ and IL-10. Cryopreservation of lymphocytes at day 8 or 12 during the cell culture may be the best choice for T cell immunotherapy.