BAL cell counts, lung MPO activity, microvascular permeability, and BAL cytokines 4 hours after transfusion of washed 10-day-old RBCs in endotoxemic mice. Washing erythrocytes immediately before transfusion did not abrogate lung injury after transfusion of 10-day-old RBCs. (A) Transfusion of washed 10-day-old RBCs increased airspace neutrophil recruitment compared with transfusion of RBCs stored for less than 1 day (P = .007). (B) Transfusion of washed 10-day-old RBCs increased lung microvascular permeability compared with transfusion of less than 1-day-old RBCs (P = .039). (C) BAL MIP-2 and KC were increased 4 hours after transfusion of washed 10-day-old RBCs (P = .021 and P < .001 for MIP-2 and KC, respectively). Data are representative of 2 independent experiments; n = 8 animals in each group.