PAF-antagonist administration after hemorrhage-resuscitation prevents splenocyte immunodepression.

A number of studies have suggested that the inflammatory and chemotactic autocoid platelet activating factor (PAF), together with various cytokines, plays an important role in the pathophysiology of trauma, sepsis, and shock. However, little is known about PAF's contribution to the immunosuppression associated with hemorrhage. The aim of our study was, therefore, to determine if the use of a PAF-antagonist following hemorrhage has any salutary effects on splenocyte lymphokine production. To study this, mice were bled to and maintained at a mean arterial pressure of 35 mm Hg for 60 min. The mice were then segregated into three groups and were resuscitated with shed blood plus lactated Ringer's solution (2x the volume of shed blood), containing either a potent PAF-antagonist (Ro 24-4736, a thienodiazepine) in dimethyl sulfoxide (DMSO) or DMSO-vehicle. Sham-operated mice received either DMSO-vehicle in saline or saline alone. Twenty-four hours thereafter the animals were sacrificed and splenocyte cultures established and stimulated for 48 hr with Con A (2.5 micrograms/ml). Supernatant lymphokine levels were determined by bioassay. The cellular release of interleukin-2 and -3 (IL-2 and IL-3) by splenocytes was significantly depressed in the nontreated or vehicle-treated hemorrhaged animals compared to shams. Treatment with the PAF-antagonist Ro 24-4736 restored IL-2 and IL-3 release values to levels comparable to those of the sham-operated animals. Thus, (1) PAF appears to play a significant role in hemorrhage-induced immunosuppression and (2) the use of a PAF-antagonist to uncouple the PAF-generated feedback loops prevents the depression in splenocyte function following hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hydroxyethyl starch after trauma-hemorrhagic shock: restoration of macrophage integrity and prevention of increased circulating interleukin-6 levels.

OBJECTIVES: To determine the effects of resuscitation with the colloidal solution (hydroxyethyl starch) vs. crystalloid solution on cell-mediated immune functions after trauma-hemorrhage. DESIGN: Prospective, multiexperimental, randomized, controlled study. SETTING: University research laboratory. SUBJECTS: Thirty-six inbred male C3H/HEN (endotoxin-sensitive) mice, aged 6 to 7 wks, and weighing 18 to 23 g. INTERVENTIONS: Crystalloid (lactated Ringer's solution) with and without 6% hydroxyethyl starch after trauma-hemorrhage. MEASUREMENTS AND MAIN RESULTS: Mice underwent laparotomy, were bled to and maintained at a blood pressure of 40 mm Hg for 60 mins, then resuscitated with either 4x the shed blood volume as lactated Ringer's solution or 2x the shed blood volume as lactated Ringer's solution plus 1 x 6% hydroxyethyl starch. Sham mice were neither hemorrhaged nor resuscitated. At 2 or 24 hrs posthemorrhage, serum, splenocytes, peritoneal macrophages, and splenic macrophages were obtained. Bioassays were used to determine interleukin-2, interleukin-3, and interleukin-6 concentrations, while splenocyte proliferation was assessed by 3H-thymidine incorporation. Trauma-hemorrhage markedly depressed splenocyte proliferation, interleukin-6 release by macrophages, and lymphokine release at 2 and 24 hrs postresuscitation. The combination of lactated Ringer's solution and hydroxyethyl starch neither restored, nor exacerbated lymphocyte functions. Interleukin-6 release by peritoneal macrophages was restored 24 hrs after hydroxyethyl starch infusion; serum interleukin-6 concentrations remained at sham levels. CONCLUSIONS: Since the use of lactated Ringer's solution and hydroxyethyl starch after hemorrhage did not adversely affect cell-mediated immune functions, but produced salutary effects on macrophage functions, hydroxyethyl starch is a safe and beneficial resuscitation adjunct.

Dextran 70 administration after trauma-hemorrhagic shock does not impair cellular immune functions.

PURPOSE: Although the effects of the colloid dextran 70 on induction of anaphylactoid reactions or reticuloendothelial phagocytosis have been examined previously, its effects on specific cell-mediated immunity after trauma-hemorrhage shock remain unknown. METHODS: Nonheparinized C3H/HeN mice underwent a laparotomy, were bled, and then maintained at a blood pressure of 35 mm Hg for 60 minutes. Then they were resuscitated with either 4 x the shed blood volume as lactated Ringer's solution (LRS) or 2 x LRS + 1 x dextran 70. Control mice underwent all operative protocols but were neither hemorrhaged, nor resuscitated. At 2 or 24 hours posthemorrhage, serum, splenocytes (SPL), and peritoneal macrophages (pM phi, splenic Mo (sM phi) were obtained. Bioassays were used to determine interleukin-2 (IL-2), IL-3, IL-6, and SPL proliferation. RESULTS: Trauma-hemorrhage markedly depressed lymphokine release, splenocyte proliferation, and IL-6 release at 2 hours after the insult. The combination of LRS + dextran did not restore lymphocyte functions, but also did not further suppress them. The release of IL-6 by pM phi and sM phi at 2 and 24 hours after dextran infusion and serum IL-6 remained at the same level as in LRS-treated animals. CONCLUSIONS: The combination of LRS and colloid dextran 70 does not adversely affect ex vivo cell-mediated immune functions during the first 24 hours after its administration after trauma-hemorrhage. Thus, from the immunological standpoint, dextran is a safe resuscitation adjunct.

Effects of trauma, duration of hypotension, and resuscitation regimen on cellular immunity after hemorrhagic shock.

OBJECTIVE: To determine the effects of: a) surgical trauma, b) crystalloid resuscitation, and c) different durations of hypotension on cellular immunity after hemorrhagic shock. DESIGN: Prospective, multiexperimental, randomized, controlled studies. SETTING: University research laboratory. SUBJECTS: Inbred C3H/HeN (endotoxin-sensitive) mice, aged 6 to 7 wks, weighing 18 to 23 g. INTERVENTIONS: Crystalloid resuscitation, with and without blood, after hemorrhage. MEASUREMENTS AND MAIN RESULTS: Mice which did or did not undergo laparotomy were subjected to hypotension of 35 mm Hg for 60 or 90 mins. Crystalloid resuscitation with and without blood was then provided. Animals were killed at 2 hrs after hemorrhage and cytokine concentrations in supernatants of splenocytes, splenic macrophages, and serum were assessed by bioassays. The cellular release of interleukin (IL)-2, IL-3, IL-6, tumor necrosis factor, and the splenocyte proliferative capacity were significantly and similarly depressed in all groups. Conversely, circulating IL-6 concentrations were significantly increased in all groups. CONCLUSIONS: Cellular immunity was depressed at 2 hrs after simple hemorrhage and no further depression occurred if hemorrhage was coupled with trauma, pure crystalloid resuscitation was provided, or the shock period was prolonged. Thus, the early immunodepression after hemorrhage was mainly dependent on the severity rather than the duration of shock, resuscitation regimen, or tissue trauma.