Evaluation of biobanked blood spot cards to detect cytokines in blood

Background & Aim Biobanks are routinely tasked with investigating new ways to store biospecimens without restricting which analytes are available. We sought to verify if very low concentration, physiologically important proteins, such as TNFα could be eluted from dried blood spot cards. While DNA and proteins are commonly extracted from biobanked samples stored as dried blood spots, it is unclear if such very low concentration proteins can be detected in suitable quality and quantity for further analysis. We chose to detect using an enzyme-linked immunosorbent assay (ELISA) approach, as ELISA is a more cost-effective approach than mass spectrometry and multiplex proximity extension assays. Methods, Results & Conclusion Different known concentrations of TNFα were loaded onto blood spot cards. After the card dried, protein was eluted from the card and quantified using an ELISA approach. It was determined that TNFα could be eluted from dried blood spot cards and quantified using ELISA. Samples eluted with a recovery of 30.1- 72.6% at concentrations on a dried blood spot between 78.13-312.5pg/ml. However, the assay's ability to detect TNFα as concentrations decreased, resulting in a decrease in the efficiency of protein recovery amount. Further refinement continues to confirm if this methodology can detect protein concentrations at common physiologic and pathologic levels of 5-27pg/ml.