Optimization of head and neck cancer peripheral blood mononuclear cell processing for robust downstream functional immune analysis

CPT™), potassium ethylenediaminetetraacetic acid (EDTA), or sodium heparin (SH) tubes and diluted 1:1 with sterile PBS or remained undiluted. PBMCs were processed and cryopreserved immediately or held for 8- and 24-hours before processing. PBMC viability was measured at cryopreservation and upon thawing. CD8+ T cells or natural killer (NK) cells derived from PBMCs were subjected to cytotoxicity assays using flow cytometry. CPT™ tubes provided lower cell viability and yield at cryopreservation and upon thaw compared to EDTA and SH tubes while dilution had no effect on viability. NK cell cytotoxicity was similar between EDTA and SH tubes irrespective of dilution. However, diluted EDTA tubes resulted in lower T cell cytotoxicity after 24-hour hold. Viability and NK and T cell cytotoxicity were equivalent between cryopreserved PBMCs that were processed immediately or processed after 8- or 24-hour hold. Here we report cryopreservation methods for reproducibility of viable cells that maintain functional immunological capacity even after significant delay in processing allowing flexibility and feasibility for collection from multiple clinical sites for deferred processing.