The acute immunological response to blood transfusion is influenced by polymicrobial sepsis.

Blood transfusion is a well-established risk factor for adverse outcomes during sepsis. The specific mechanisms responsible for this effect remain elusive, and few studies have investigated this phenomenon in a model that reflects not only the clinical circumstances in which blood is transfused, but also how packed red blood cells (PRBCs) are created and stored. Using a cecal ligation and puncture model of polymicrobial sepsis as well as creating murine allogeneic and stored PRBCs in a manner that replicates the clinical process, we have demonstrated that transfusion of PRBCs induces numerous effects on leukocyte subpopulations. In polymicrobial sepsis, these responses are profoundly dissimilar to the proinflammatory effects of PRBC transfusion observed in the healthy mouse. Transfused septic mice, as opposed to mice receiving crystalloid resuscitation, had a significant loss of blood, spleen, and bone marrow lymphocytes, especially those with an activated phenotype. Myeloid cells behaved similarly, although they were able to produce more reactive oxygen species. Overall, transfusion in the septic mouse may contribute to the persistent immune dysfunction known to be associated with this process, rather than simply promote proinflammatory or anti-inflammatory effects on the host. Thus, it is possible that blood transfusion contributes to the multiple known effects of sepsis on leukocyte populations that have been shown to result in increased morbidity and mortality.