Interleukin-1 enhances murine granulopoiesis in vivo.

Interleukin-1 (IL-1), a monokine involved in host response to infection and inflammation, has recently been shown to stimulate production of granulocyte-monocyte colony-stimulating factors (CSFs) from a variety of cell types in vitro. The purpose of this study was to investigate the effects of human IL-1 on granulopoiesis in vivo. CF1 female mice were injected with a single dose of either highly purified human IL-1 or recombinant human IL-1 alpha (rIL-1 alpha). Heat-inactivated IL-1 or rIL-1 alpha served as controls. Physiologic doses of the IL-1 preparations were initially established by evaluating neutrophil egress from bone marrow (BM). Significant peripheral neutrophilia developed 3 h after injection of 10 U (doubling units) purified IL-1, in association with decreased marrow neutrophils. Significant neutrophilia occurred 6 h after injection of 5 x 10(3) U (half-maximal units) rIL-1 alpha. Serum colony-stimulating activity (CSA) and BM colony formation (CFU-GM) were subsequently measured in standard agar culture at various times following injection. A significant rise in CSA occurred between 3 and 6 h after injection of purified IL-1, and a significant increase in BM CFU-GM developed 48 h after injection. Similar increases in CSA and CFU-GM occurred following injection of rIL-1 alpha. These results suggest that IL-1 may play an important role in the regulation of granulopoiesis in vivo by enhancing the production of CSFs required for myeloid proliferation.

Inadequate granulopoiesis after major torso trauma: a hematopoietic regulatory paradox.

Late postinjury sepsis is largely the result of defective host defense including failure to maintain an adequate number of functioning phagocytic cells. In this study we used stem cell culture techniques to measure colony-stimulating activity and have quantitated the number of circulating myeloid stem cells to see if defects in granulopoiesis occur after major torso trauma. Forty-two acutely injured patients (13 blunt and 29 penetrating injuries; mean age, 29.7 years) undergoing laparotomy with an abdominal trauma index of 15 to 40 were studied prospectively. Blood samples were obtained on days 1, 5, and 10. Patients were segregated by injury severity: abdominal trauma index less than 25 (n = 25) versus abdominal trauma index greater than or equal to 25 (n = 17). The more severely injured (abdominal trauma index greater than or equal to 25) patients had fewer circulating granulocytes and monocytes. Colony-stimulating activity was below normal control levels in all patients and was decreased further with increased injury severity. The more severely injured patients had a blunted bone marrow response (significantly fewer circulating myeloid stem cells) and suffered more major septic complications (24% vs 8%). In conclusion, major trauma to the torso causes a paradoxic depression in granulopoiesis that worsens with increased injury severity and may contribute to late septic morbidity. This colony-stimulating activity deficiency state is similar to that seen after major burns and may be amenable to future modulation.

Total enteral nutrition versus total parenteral nutrition after major torso injury: attenuation of hepatic protein reprioritization.

Reprioritization of hepatic protein synthesis, a process involving accelerated production of acute-phase proteins at the expense of constitutive proteins, accompanies major trauma. The impact of isocaloric, isonitrogenous total enteral nutrition (TEN) versus total parenteral nutrition (TPN) on hepatic reprioritization was investigated in a prospective, randomized trial. Of the 59 patients with an abdominal trauma index (ATI) greater than 15 but not more than 40, 45 evaluable patients were followed. Results from 36 (18 TEN, 18 TPN) evaluable patients revealed that mean serum levels of acute-phase proteins increased, whereas mean serum levels increased to a greater extent in the TPN group. The maximal increase from baseline for the acute-phase response in both groups occurred at postinjury day 5 and was significantly higher for alpha 1-antitrypsin (alpha 1AT, p = 0.03) and orosomucoid (p = 0.02) in the TPN group. Nonacute-phase proteins reached a nadir at day 10 in the TPN group and increased in the TEN group; significant differences between TEN and TPN groups appeared for albumin (p = 0.004) and retinol-binding protein (RBP, p = 0.03); alpha 2-macroglobulin (alpha 2M) approached significance at day 10 (p = 0.07). When change from baseline values was compared, day 10 increases in alpha 2M were significantly higher (p = 0.04) in the TEN group. These data suggest that postinjury TEN attenuates reprioritization of hepatic protein synthesis in patients sustaining major trauma.

The myelopoietic effects of a Serratia marcescens-derived biologic response modifier in a mouse model of thermal injury.

The proliferative defects observed in phagocytic stem cells after major thermal injuries may be caused by an inadequate production of colony-stimulating factors (CSFs), a family of hemopoietic cytokines necessary for the production and function of granulocytes and monocytes. In this study a biologic response modifier (S-BRM) consisting of sized vesicles derived from the cell membrane and ribosomes of Serratia marcescens was investigated in a mouse model of thermal injury to determine its ability to augment postburn myelopoiesis. Treatment of burned mice with S-BRM was well tolerated and was associated with statistically significant increases in absolute numbers of circulating granulocytes and monocytes compared with burned mice receiving saline solution. In addition, the size of the splenic myeloid stem cell compartment, as measured by granulocyte-macrophage stem cell colony formation in soft agar, was markedly expanded. Finally, plasma levels of CSF were increased significantly in burned mice receiving S-BRM but were not elevated in burned littermates treated with saline solution. These data suggest that production of CSF is suboptimal after thermal injury and S-BRM is capable of up-regulating postburn myelopoiesis by causing the release of CSF into the systemic circulation.

Recombinant human interleukin-1 receptor antagonist protects early myeloid progenitors in a murine model of cyclophosphamide-induced myelotoxicity.

Expression of hematoregulatory cytokines such as interleukin-1 (IL-1) in response to cytotoxic chemotherapy hastens hematopoietic recovery, but may also potentiate myelotoxicity if myeloid progenitors enter cell cycle before drug clearance. In the present study, the ability of recombinant human IL-1 receptor antagonist (IL-1ra) to protect hematopoietic progenitors was studied in a murine model of cyclophosphamide (CPA)-induced myelotoxicity. CF-1 female mice received 200 mg/kg CPA and either 10 mg/kg IL-1ra or an equal volume of 0.05% human serum albumin (HSA) intraperitoneally (i.p.), followed 12 hours later by IL-1ra or HSA. CPA and IL-1ra increased absolute neutrophil counts (ANCs) at days 2 (P = .001) and 14 (P = .0025) after CPA. In IL-1ra-treated mice, colony-forming units granulocyte-macrophage (CFU-GM)/tibia were increased twofold and threefold at days 2 (P = .0047) and 7 (P = .023), respectively, whereas high proliferative potential colony-forming cells (HPP-CFC)/tibia were decreased twofold to threefold at 8 hours (P = .039) and 24 hours (P = .0033), but were approximately threefold higher than HSA-treated mice at day 7 after CPA. Coadministration of CPA and IL-1 enhanced myelotoxicity compared with mice injected with CPA and IL-1ra or HSA. In vivo, IL-1ra protected HPP-CFC, but not CFU-GM, from hydroxyurea suicide after a single dose of CPA, suggesting that IL-1ra inhibited cycling of HPP-CFC. In vitro, IL-1ra did not alter proliferation of CFU-GM, but inhibited IL-1-enhanced proliferation of HPP-CFC. These data suggest that IL-1ra acts as an indirect negative regulator of hematopoiesis and protects HPP-CFC from CPA, possibly by inhibiting IL-1-enhanced proliferation of early myeloid progenitors.

Postburn serum inhibits in vitro production of colony-stimulating factor by mononuclear peripheral blood cells.

The effects of postburn serum (PBS) on the production of colony-stimulating factor (CSF) was evaluated in 13 burned patients by adding PBS to normal peripheral blood mononuclear cells (MNC) and assaying the MNC-conditioned media for CSF content. PBS inhibited CSF production by at least 50%. PBS from non-survivors significantly inhibited CSF production more than PBS from survivors. The addition of lithium chloride restored production of CSF in the presence of day 15 PBS but could not overcome the inhibitory effects of day 1 or day 8 PBS. The nature of the inhibitor(s) is uncertain, but correction of the CSF production defect by lithium chloride later in the course of thermal injury suggests that the defect may be reversible.

Vitamin E improves cell-mediated immunity in the burned mouse: a preliminary study.

Profound immunosuppression occurs after major burn injuries. The ability of vitamin E to prevent post-burn immunosuppression was tested in mice using ear swelling in response to a challenge with 2,4-dinitrofluorobenzene (DNFB) as an in vivo measure of cell-mediated immunity (CMI). Vitamin E was administered to burned mice every other day for 14 days by either the topical or intraperitoneal route. Dimethyl sulphoxide (DMSO) was compared to white petroleum jelly (VAS) as a vehicle for topically administered vitamin E. Mean CMI +/- the standard error of the mean (SEM) was depressed to 55 +/- 4 per cent of normal control in untreated burned mice. Treatment with either parenteral vitamin E in corn oil or topical vitamin E in DMSO improved CMI dramatically compared to burned controls (P less than 0.005) while vitamin E in VAS had a less beneficial effect on CMI (P less than 0.05). We conclude that vitamin E is an effective immunomodulator in burned mice.

Granulocyte stem cells are decreased in humans with fatal burns.

The number of granulocytic stem cells (CFU-C) was measured in the peripheral blood of surviving and nonsurviving burned humans. It has been shown that the number of CFU-C in the peripheral blood of survivors increases over time and is elevated compared to the number found in normal humans. The number found in nonsurvivors, however, falls significantly in the later stages of burn injury, suggesting perhaps a defect in stem cell production and/or differentiation in patients with severe thermal injuries. The mechanism is unclear but its delineation may have an important bearing on understanding the nature of infectious complications following thermal injury.

Regulation of granulopoiesis following severe thermal injury.

Neutropenia often accompanies septicemia in burned patients. This paradox suggests a defect in the regulation of granulopoiesis. Colony stimulating factor (CSF) produced by the monocyte-macrophage system is an important regulator of granulocyte production. We followed serial serum CSF levels and peripheral blood leukocyte differential counts in 22 patients with greater than 30% burns. Six patients (mean burn, 58%) developed Gram-negative septicemia and died (Group I). Sixteen patients (mean burn, 38%) had no fatal septicemias (Group II). Nonsurvivors had initially low levels of CSF and developed persistent monocytopenia. Survivors, in contrast, had prompt rises in CSF and developed monocytosis. The presence of monocytopenia and low CSF levels in Group I suggests an abnormality in the stimulatory arm regulating granulopoiesis. Such a defect may play a role in the development of fatal septicemia following severe thermal injury.