TRAUMA-HEMORRHAGE CAUSES PROLONGED DEPRESSION IN CELLULAR-IMMUNITY

A number of clinical studies have shown that multiple and severe traum a causes immunosuppression and increases the susceptibility to sepsis. However, because there is a close temporal relationship between traum a and hemorrhage in humans, it is difficult to dissociate the effects of tissue trauma versus hemorrhage on immunity in the clinical setting . Studies in mice;have shown that simple hemorrhage per se as well as laparotomy alone produces a marked depression in cellular immunity and no difference was seen in the extent of depression at 2 h if these tw o insults were combined. Nonetheless, it remains unknown whether the c ombined model of trauma-hemorrhage produces a more protracted depressi on in immune function. To study this, 5 days after either sham operati on, laparotomy (i.e.trauma), hemorrhage alone (35 mmHg for 1 h, follow ed by resuscitation), or the combination of laparotomy and hemorrhage, mice (C3H/HeN) were sacrificed, after which splenocyte and peritoneal macrophage cultures were established. The proliferative capacity of t he splenocytes, as well as their ability to release IL-2 and IL-3, was markedly decreased in the trauma-hemorrhage animals but was normal in the other groups. Furthermore, the release of IL-6 by peritoneal macr ophages from animals that underwent trauma-hemorrhage was also signifi cantly depressed. These results support the concept that traumatic inj ury in the form of a midline laparotomy combined with hemorrhage produ ces a more protracted impairment in cell-mediated immunity than laparo tomy or hemorrhage alone.