Synth a freeze cryopreservation medium

On day 12 of expansion, γδ T cells were washed and prepared for cryopreservation. For studies comparing different GMP-grade freezing media, γδ T cells were washed and resuspended at 1 × 10⁷ cells/mL in one of the 5 media tested: Synth-a-Freeze Cryopreservation Medium (ThermoFisher Scientific), GIBCO Recovery Cell Culture Freezing Medium (ThermoFisher Scientific), STEM-CELLBANKER (amsbio), Nutrifreez D10 Cryopreservation Medium (Biological Industries), or 5% human albumin (2.5g human albumin in 50 mL aqueous diluent, Grifols Therapeutics) with 10% Me2SO. For all subsequent experiments, γδ T cells were cryopreserved in 5% human albumin (2.5g human albumin in 50 mL aqueous diluent, Grifols Therapeutics) with 10% Me2SO. Cells were frozen at a rate of −1°C per minute. When the cells reached −80°C, they were promptly moved to liquid nitrogen.