Transfusion of 35-day stored red blood cells does not result in increase of plasma non-transferrin bound iron in human endotoxemia.

Abstract

Transfusion of a single unit of stored red blood cells (RBCs) has been hypothesized to induce supra-physiological levels of non-transferrin bound iron (NTBI), which may enhance inflammation and act as a nutrient for bacteria. We investigated the relation between RBC storage time and iron levels in a clinically relevant "two-hit" human transfusion model. Eighteen healthy male volunteers (ages 18-35 years) were infused with 2 ng lipopolysaccharide (LPS)/kg to induce systemic inflammatory response syndrome. Two hours later, each participant received either 1 unit of 2-day stored (2D) autologous RBCs, 35-day stored (35D) autologous RBCs, or an equal volume of saline. Every 2 hours up to 8 hours after LPS infusion, hemoglobin, hemolysis parameters, and iron parameters, including NTBI, were measured. Transfusion of both 2D and 35D RBCs caused increases in hemoglobin, plasma iron, and transferrin saturation; whereas levels remained stable in the saline group. Transfusion of 35D RBCs did not result in hemolysis nor did it lead to increased levels of NTBI compared with 2D RBCs or saline. LPS induced increases in ferritin, haptoglobin, bilirubin, and lactate dehydrogenase that were similar in all three groups. We conclude that 35D autologous RBCs do not cause hemolysis or increased levels of NTBI during human endotoxemia.