Association between gene expression biomarkers of immunosuppression and blood transfusion in severely injured polytrauma patients

OBJECTIVE To explore the hypothesis that blood transfusion contributes to an immunosuppressed phenotype in severely injured patients. BACKGROUND Despite trauma patients using disproportionately large quantities of blood and blood products, the immunomodulatory effects of blood transfusion in this group are inadequately described. METHODS A total of 112 ventilated polytrauma patients were recruited. Messenger RNA (mRNA) was extracted from PAXGene tubes collected within 2 hours of the trauma, at 24 hours, and at 72 hours. T-helper cell subtype specific cytokines and transcription factors were quantified using real-time polymerase chain reaction. RESULTS Median injury severity score was 29. Blood transfusion was administered to 27 (24%) patients before the 2-hour sampling point. Transfusion was associated with a greater immediate rise in IL-10 (P = 0.003) and IL-27 (P = 0.04) mRNA levels. Blood products were transfused in 72 (64%) patients within the first 24 hours. There was an association between transfusion at 24 hours and higher IL-10 (P < 0.0001), lower Foxp3 (P = 0.01), GATA3 (P = 0.006), and RORγt (P = 0.05) mRNA levels at 24 hours. There were greater reductions in T-bet (P = 0.03) mRNA levels and lesser increases in TNFα (P = 0.015) and IFNγ (P = 0.035) at 24 hours in those transfused. Multiple regression models confirmed that the transfusion of blood products was independently associated with altered patterns of gene expression. Blood stream infections occur in 15 (20.8%) of those transfused in the first 24 hours, compared with 1 patient (2.5%) not transfused (OR = 10.3 [1.3-81], P = 0.008). CONCLUSIONS The primarily immunosuppressive inflammatory response to polytrauma may be exacerbated by the transfusion of blood products. Furthermore, transfusion was associated with an increased susceptibility to nosocomial infections.