Soluble urokinase plasminogen activator receptor in blood transfusion components

Summary.  Post‐transfusion infectious complications associated with allogeneic blood components may depend on storage time and may be related to extracellular accumulation of bioactive substances during storage. The glycoprotein, soluble urokinase plasminogen activator receptor (suPAR), which is located in specific granules of neutrophils, plays a role in inflammation and remodelling of the extracellular matrix. Using enzyme‐linked immunosorbent assay, suPAR was determined in serum, plasma and blood cell lysates. In addition, suPAR was measured in whole blood (WB), buffy‐coat‐depleted saline‐adenine‐glucose‐mannitol (SAGM) blood, platelet‐rich plasma (PRP) and buffy‐coat‐derived platelet (BCP) pools with and without pre‐storage leucofiltration, and in non‐filtered WB, SAGM blood and platelet concentrates prepared using apheresis (APC) at different time points during storage. Mean suPAR concentration was significantly higher in cell lysates, compared to that in a corresponding serum (P = 0·007) and in plasma samples (P = 0·004). Mean suPAR levels in WB, BCP and SAGM were significantly reduced using leucofiltration (WB: 3·4 versus 2·0 ng mL−1; BCP: 1·6 versus 1·1 ng mL−1; SAGM: 2·8 versus 0·19 ng mL−1), whereas no difference was observed in PRP. In non‐filtered WB, SAGM and APC, extracellular suPAR accumulated significantly in a storage‐time‐dependent manner (WB: P < 0·01; SAGM: P < 0·001; APC: P < 0·001). The present study demonstrates that cell lysates contain significantly more suPAR, compared to both serum and plasma. This can be explained by the release of suPAR from intracellular granules during cell lysis. The amount of suPAR is significantly increased during storage of blood transfusion components, an accumulation that is reduced using pre‐storage leucofiltration.