Transfusion of WT or Duffy KO RBCs during endotoxemia. Mice were transfused with 1- to 2-day-old KO or WT RBCs 2 hours after LPS administration. (A) Transfusion of KO RBCs increased BAL cytokines 4 hours after transfusion compared with WT RBC transfusion (P = .008, .022, .022, and .013 for MIP-2, KC, IL-6, and TNF-α, respectively). (B) Total BAL mononuclear cells were similar between the KO and WT RBC transfused animals (P = .233). There was a significant increase in airspace neutrophil counts in the KO RBC transfused animals compared with WT RBC transfused animals (P < .001). (C) Transfusion of KO RBCs increased lung microvascular permeability compared with transfusion of WT RBCs (P = .034). Data are representative of 3 individual experiments; n = 12 in each experimental group.