Leukocyte Responses to Injury

Clinical and laboratory studies during the past two decades have documented that changes in leukocyte number and function can represent both the causes and the effects of infection, sepsis, and injury in surgical patients. Injury elicits a response from the immune system that is proportional to the magnitude of the insult and causes impaired function in some cells while sensitizing other cells so that a second insult will trigger an exaggerated and prolonged response. The cytokines and other metabolic products of activated leukocytes are also recognized as mixed blessings which, depending on magnitude and time of production, can act either beneficially to provide or enhance host resistance and thereby prevent or control infection, or deleteriously to depress the function of remote organs and cause systemic inflammation associated with cellular death and tissue injury.