Impact of Serum Omission on Clinical ELISpot Assays

This study investigates the impact of omitting serum from blood wash buffer, cryomedium, or cell culture medium on T-cell function in the context of Enzyme-Linked Immunospot (ELISpot) assays. Although serum-free freezing media demonstrated comparable viability and IFN-γ secretion from peripheral blood mononuclear cells (PBMCs) as serum-containing cryopreservation media, the effects of prolonged storage in liquid nitrogen remained unclear. Furthermore, the timely isolation of PBMCs from whole blood samples presents challenges for large-scale studies, and the potential solution of a Central Processing Lab (CPL) with a 48-hour processing delay requires further evaluation. The study finds minimal impact on T-cell viability and T-cell function when omitting serum in cryopreservation. Additionally, serum-containing wash medium and cell culture medium is vital for optimized assay performance following 48-hour delayed processing. These findings provide insights for selecting appropriate mediums for clinical ELISpot studies, offering potential serum-free alternatives for processing fresh blood samples while highlighting the importance of serum-containing medium in CPL-based approaches.