Apoptosis: a method for evaluating the cryopreservation of whole blood and peripheral blood mononuclear cells

We sought to compare the effect of cryopreservation and storage at −30°C, −70°C and −150°C of human whole blood versus matched peripheral blood mononuclear cell (PBMC) samples using apoptosis as an indicator of cell fitness. Following 10 weeks of storage the samples were thawed and assessed for viability (trypan blue exclusion), levels of apoptosis (using the nuclear stain bis-benzimide) and cell function (ability to be transformed by Epstein–Barr virus, EBV). When comparing storage temperatures, the levels of apoptosis in whole blood and PBMC samples stored at −30°C were significantly higher than the values for samples stored at −70°C or −150°C ( P