Packed blood cells stored in AS-5 become proinflammatory during storage

BACKGROUND: Studies have shown that packed blood cells (PBCs) stored in AS‐1 (Adsol, Baxter) and AS‐3 (Nutricel, Medsep Corp.) accumulate proinflammatory substances, which may contribute to increased complications from allogeneic blood transfusion. This study assessed whether supernates from PBCs stored in AS‐5 (Optisol, Terumo Corp.) prime neutrophils (PMNs), activate platelets (PLTs), and accumulate proinflammatory cytokines and PMN granule constituents. STUDY DESIGN AND METHODS: PBC units were prepared in AS‐5 from nonleukoreduced (NLR) and leukoreduced (LR) whole‐blood units and stored at 4°C. Supernates from samples of PBCs collected at various storage times were analyzed by multiplex enzyme‐linked immunosorbent assay for proinflammatory cytokines and myeloperoxidase (MPO) and were incubated with type‐matched blood, which was assessed by flow cytometry for expression of CD11b on PMNs, CD62P on PLTs, and formation of PMN‐PLT aggregates. RESULTS: Supernates from NLR PBCs stored for at least 14 days elevated CD11b expression on PMNs and the number of PMN‐PLT aggregates compared to supernates from collection day PBCs. The magnitude of these effects correlated with storage age. Supernates from LR PBCs did not elicit these responses. Expression of CD62P on PLTs was not affected by supernates from either NLR or LR PBCs. Levels of interleukin (IL)‐1β, IL‐6, IL‐8, IL‐18, NAP‐2, MCP‐1, RANTES, and MPO were elevated in supernates from 28‐ and 42‐day NLR units. Tumor necrosis factor α and MIP‐1α did not increase, and cytokine levels in LR PBC units did not increase. CONCLUSION: Units of NLR PBCs stored in AS‐5 become increasingly proinflammatory as a function of storage time. Leukoreduction prevents this change.