Transfusion-induced leukocyte IL-8 gene expression is avoided by the use of human polymerized hemoglobin

Background: Red blood cell (pRBC) transfusion is an independent risk factor for multiple organ failure (MOF); a maladaptive immuno-inflammatory response is implicated. Interleukin-8 (IL-8) is one putative mediator of this response. We previously observed that injured patients resuscitated with pRBCs have increased plasma IL-8 compared with those given human polymerized hemoglobin (PolyHb). To further elucidate the mechanisms responsible for this difference in IL-8, we devised an ex-vivo transfusion model. We hypothesize that pRBC transfusion induces increased IL-8 gene expression that is avoided by the use of PolyHb. Methods: Human volunteer blood was incubated alone (RB) or with a major transfusion (50% exchange) of either post-storage leukoreduced O-pRBCs (RB + pRBC) or PolyHb (RB + PolyHb) for 30 minutes at 37°C. Total leukocyte (TL) or polymorphonuclear leukocyte (PMN) total RNA was isolated and IL-8 mRNA quantified. Results are reported as amol IL-8 mRNA/μg total RNA ± SEM. Stats: ANOVA with Bonferroni/Dunn post hoc analysis. Results: Simulated transfusion of pRBCs increased TL IL-8 mRNA (RB = 0.28 ± 0.10 amol/μg total RNA, RB + pRBC = 2.24 ± 0.25 amol/μg total RNA, p < 0.01), whereas PolyHb did not (B + PolyHb = 0.82 ± 0.30 amol/μg total RNA). PolyHb IL-8 mRNA was less than pRBC transfused (p < 0.01). In PMNs, simulated transfusion of pRBCs increase IL-8 mRNA (RB = 3.17 ± 1.05 amol/μg total RNA, RB + pRBC = 7.60 ± 1.79 amol/μg total RNA, p < 0.01), whereas PolyHb did not (RB + PolyHb = 4.53 ± 1.64 amol/μg total RNA). Conclusion: Stored pRBCs induces increased TL and PMN IL-8 gene expression, whereas human polymerized hemoglobin, in lieu or pRBCs, avoids this increase. These experimental results corroborate our previous clinical studies and further encourage the study of PolyHb as a resuscitation strategy to decrease postinjury MOF.