Immunology of trauma

Abstract

Systemic inflammation involves a large number of mediators and effector mechanisms. One approach to understanding systemic inflammation is to interpret the nature of the response based on the effector mechanisms that are observed. An alternative approach is to consider these effector responses in the context of our current understanding of immunoregulation. The aim of this article is to provide an overview of the immune response and discuss the mechanisms of immunoregulation in order to provide non-immunologists with a framework for understanding the normal and aberrant immune responses that can be precipitated by major trauma. The clinical manifestations of the inflammatory response to major trauma resemble those observed after other significant insults (surgery, burns, and pancreatitis). Furthermore, the clinical manifestations, changes in serum proteins, and pattern of immune activation point to the presence of infection, yet proof of a contribution by infection to the pathogenesis by infection remains elusive. Although inflammation dominates the early phase of the response, there is often evidence of a paradoxical combination of inflammation and immunosuppression later on. Consideration of the proinflammatory cascades, and the contribution of the innate immune system, helps explain why the clinical picture after major trauma may resemble other clinical states. It also explains the counter-regulatory response, which normally acts to downregulate inflammation, but may cause immunosuppression in the face of persistent inflammation after major trauma.