Accumulation of oxidized peroxiredoxin 2 in red blood cells and its prevention

Background: The thiol protein peroxiredoxin 2 (Prx2) is a major red blood cell (RBC) antioxidant that breaks down hydroperoxides and in the process is converted to an oxidized disulfide. Our objective was to determine whether Prx2 becomes oxidized during storage of RBCs, to understand the underlying mechanism, and to find ways of preventing the accumulation of the oxidized form. Study design and Methods: RBCs were stored for up to 6 weeks under simulated blood banking conditions and Prx2 oxidation was monitored by nonreducing gel electrophoresis. The ability of the cells to reverse Prx2 oxidation after storage and to respond to added hydrogen peroxide was also evaluated. Results: Prx2 remained predominantly reduced during the first 3 weeks of storage, and then the oxidized form accumulated progressively. In contrast to fresh cells, oxidation was not reversed by incubation with glucose. Storage of RBCs in a high-pH, low-chloride, and high-phosphate/bicarbonate buffer (EAS-76v6) largely prevented accumulation of oxidized Prx for at least 6 weeks, and dihydrolipoic acid (DHLA), but not Rejuvesol, N-acetylcysteine, or a-lipoic acid, was able to reverse or protect against Prx2 oxidation. Additional, Prx2 oxidation occurred when hydrogen peroxide was added. However, this was reversible, suggesting that the reductive capacity was compromised in some but not in all cells. Conclusion: Prx2 remains mostly reduced in a high-pH storage solution with buffering capacity. Addition of DHLA to stored RBCs might be advantageous. Prx2 redox status could be used as a biomarker for the quality of stored RBCs.