Interferon Alpha is Stable for at Least Twenty Days in Dried Blood Spots

Abstract

Dried blood spot (DBS) cards are a simple, inexpensive, and convenient method for storage and analysis of blood samples. DBS samples have been used for the analysis of a variety of markers such as proteins, enzymes, cytokines, nucleic acids, fatty acids, and drugs. One of the beneficial properties of these cards is their ability to be stored for long periods of time with little to no deterioration or degradation of analytes, especially when stored in colder temperatures. The primary objective of this study was to determine the stability of a cytokine, interferon-alpha (IFN-α), in DBS cards stored at room temperature for 20 days without any additional treatments or additives. Blood samples were spiked with IFN-α standard and stored on DBS cards in the dark at room temperature with desiccant for up to 20 days. Concentration of IFN-α was measured using an ELISA immunoassay. Total protein extracted was also measured by a Bradford Assay to account for any decreases in concentration. Total protein and IFN-α were quantitated and analyzed using Kruskal-Wallis, the Bonferroni Procedure, and One-Sample-T-Tests. IFN-α was detectable in all spiked samples, and little to no degradation of the protein was observed at day 20. Total protein extracted from DBS ranged from 30-50%. Concentrations of IFN-α were as expected based on the dilution of the standard after accounting for protein extraction. Improved protein extraction methods will be assessed to improve the assay. These data provide evidence of the feasibility of assessing IFN-α using DBS technology which may facilitate international research projects.