How are cell counts and viabilities of PBMCs determined?

Cell counts and viability are determined using a Nexcelom Cellometer® with acridine orange and propidium iodide to identify live and dead nucleated cells, respectively. Unlike dissociated tissue, which is prone to cellular debris, PBMCs can be counted using trypan blue exclusion. If flow cytometry is used to determine cell count and viability, it is recommended that proper FSC thresholds be established to remove platelets, which are present in cryopreserved PBMCs.