Trauma- and Transfusion-induced Immunomodulation

Both transfusion and traumatic injury have been shown to have strong effects on the immune system. Trauma patients have been shown to be either immunosuppressed or hyperactivated. making them vulnerable to serious immune sequelae such as sepsis and multiorgan failure, and it was previously thought that this was the result of initial immune activation followed by a compensating period of suppression. Using samples collected from transfused and non-transfused trauma patients starting with arrival in hospital and tracking for up to a year after injury, we screened for over 40 soluble immune mediators in the circulation and demonstrated that a generally immunosuppressive cytokine milieu develops very early but that this includes some overlapping production of pro-inflammatory cytokines. We were also able to look at the impact of transfusion on this immune deregulation, developing a novel model to separate out the effects of traumatic blood loss and transfusion. We have since further adapted this model to look at the immunomodulatory impact of transfusion of different blood products in various settings. In addition, using longitudinal samples from a large contemporary cohort of trauma patients, we demonstrated that the phenomenon of transfusion-associated microchimerism, unique to the setting of trauma, is effectively eliminated with the use of modern leukoreduced blood products.