Mechanisms of immunosuppression associated with severe nonthermal traumatic injuries in man: production of interleukin 1 and 2

What is Acute Respiratory Distress Syndrome?

Acute respiratory distress syndrome (ARDS) is a form of acute lung injury which usually occurs within 24 hours of a major illness or injury. Unfortunately a clear definition of ARDS does not presently exist, and the variability in the diagnostic criteria may impact on the results of clinical trials for ARDS and our understanding of the epidemiology and pathogenesis of this syndrome. In this article the history of ARDS is reviewed and a few of the definitions that have evolved over wtime are explored in depth. In addition, several controversies with these existing defiitions are discussed.

Factors involved in early in vitro endotoxin hyporesponsiveness in human endotoxemia

Sepsis and endotoxemia induce a state of early tolerance to the biological effects of endotoxin. Relatively little is known about the mechanisms or mediators involved in this endotoxin hyporesponsiveness. In this study endotoxin-induced TNF production of whole blood obtained at different time points from endotoxin challenged volunteers, and endotoxin- and PHA-induced TNF production by healthy PBMNCs in the presence of serum from endotoxin challenged volunteers were compared.

Endotoxin-induced TNF production by whole blood was found to be significantly reduced at 2 h after in vivo endotoxin administration, returning to baseline levels at t = 6 h. In addition, a reduction of TNF produced by healthy PBMNCs in the presence of post-endotoxin serum was observed. No correlation was found with the concentration of any of the well described anti-inflammatory mediators investigated nor with plasma levels of endotoxin-binding proteins.

Atypical Presentation of Tuberculosis of Elbow Joint in Operated Case of Distal Humerus Fracture

Introduction:

A typical presentations of tuberculosis are not uncommon. Periprosthetic infection with tuberculosis after total joint replacement has well published. Tuberculosis of the elbow following open reduction internal fixation of a distal humerus fraeture is extremely rare.

Case Report:

We report case of a healthy, immunocompetenet 49-year-old male who underwent open reduction and internal fixation with bicolumnar plating for distal humerus fracture and presented after 18 month with cystic swelling over medial aspect of operated site. There was no wound dehiscence and the underlying fracture was healed well without any signs of implant loosening or bony involvement. Cystic swelling was excised and histopathology provided the diagnosis of tuberculosis. Patient was treated with anti tubercular chemotherapy and patient made uneventful recovery.

Conclusion:

Although synovial tuberculosis after fracture fixation is a rare entity, tuberculosis should be kept as a differential diagnosis. Surgeons should have high index of suspicion to diagnose atypical presentations of tuberculosis.

Implant-associated mycobacterium tuberculosis infection following surgical management of fractures: a retrospective observational study

In this retrospective observational cohort study, we describe 17 patients out of 1775 treated for various fractures who developed mycobacterium tuberculosis (MTB) infection after surgery. The cohort comprised 15 men and two women with a mean age of 40 years (24 to 70). A total of ten fractures were open and seven were closed. Of these, seven patients underwent intramedullary nailing of a fracture of the long bone, seven had fractures fixed with plates, two with Kirschner-wires and screws, and one had a hemiarthroplasty of the hip with an Austin Moore prosthesis. All patients were followed-up for two years. In all patients, the infection resolved, and in 14 the fractures united. Nonunion was seen in two patients one of whom underwent two-stage total hip arthroplasty (THA) and the other patient was treated using excision arthoplasty. Another patient was treated using two-stage THA. With only sporadic case reports in the literature, MTB infection is rarely clinically suspected, even in underdeveloped and developing countries, where pulmonary and other forms of TB are endemic. In developed countries there is also an increased incidence among immunocompromised patients. In this paper we discuss the pathogenesis and incidence of MTB infection after surgical management of fractures and suggest protocols for early diagnosis and management.

Tubercular infection after arthroscopic anterior cruciate ligament reconstruction

PURPOSE

Tubercular infection has not been described, to our knowledge, in the literature after anterior cruciate ligament (ACL) reconstruction, and, hence, the purpose of our case series was to describe our experience, evaluate the clinical and laboratory findings, and assess the treatment outcome.

METHODS

We performed a retrospective analysis of 1,152 cases of arthroscopic ACL reconstruction with autografts performed at our institution between January 1998 and May 2007. Tubercular infection was considered to be present in the setting of recurrent negative bacterial cultures but a positive result on microscopy, culture, histopathology, or polymerase chain reaction (PCR). All patients underwent arthroscopic lavage and synovectomy, followed by antitubercular therapy for 12 months.

RESULTS

We identified 8 patients (0.69%) with infection. Bone-patellar tendon-bone graft was used in 1 and hamstring graft in 7. All patients were immunocompetent. The mean time from surgery to presentation was 64.4 days (range, 23 to 152 days). Aspirate fluid staining and culture for acid-fast bacilli was negative in all cases, synovial tissue culture was positive in 3, characteristic histopathology was positive in 7, and PCR was positive in 6. A mean of 1.25 surgeries (range, 1 to 2) were performed. The mean length of follow-up in our series was 43.6 months (range, 25 to 73 months), with no reinfections. The mean postoperative Lysholm knee score was 80.

CONCLUSIONS

Tubercular infection as a complication after arthroscopic ACL reconstruction, though rare, should be kept in mind as a possible cause of infection in immunocompetent patients in zones endemic for tuberculosis. It should also be kept in mind in nonendemic areas, among immigrants from endemic areas, and in cases with persistent swelling and discharge, effusion with minimal inflammatory signs, and negative cultures. We recommend deoxyribonucleic acid-PCR testing for early diagnosis of tuberculosis. Arthroscopic debridement and antitubercular chemotherapy together are the mainstay of treatment.

Heat shock factor 1 inhibits nuclear factor-kappaB nuclear binding activity during endotoxin tolerance and heat shock

RATIONALE

Sepsis, endotoxin tolerance, and heat shock (HS) all display down-regulation of innate immunity. We hypothesize that HS factor 1 (HSF-1) induces competitive inhibition of nuclear factor-kappaB (NF-kappaB)-induced signal transduction in both endotoxin tolerance and HS.

OBJECTIVES

We compared endotoxin tolerance and HS in RAW 264.7 cells. We transfected cells with an HS protein 70 (HSP70) plasmid to test whether HSP70 is the mediator of HS-induced NF-kappaB inhibition. We studied the effects of endotoxin stimulation and HS, both separately and together, on "wild-type" cells, cells transfected with the HSP70 plasmid, and cells transfected with vehicle.

FINDINGS

Heat shock protein 70 plasmid-transfected cells had increased HSP70 expression and demonstrated decreased nitric oxide (NO) release and inducible NO synthase messenger RNA expression in response to endotoxin compared with wild-type and empty plasmid-transfected cells. Heat shock completely abolished subsequent NO and inducible NO synthase messenger RNA expression in wild-type cells. Heat shock factor 1 reached maximum expression 60 to 90 minutes after HS. Heat shock protein 70-transfected cells still displayed endotoxin-induced NF-kappaB nuclear binding, whereas endotoxin tolerance, HS, and exposure to HSF-1, but not exposure to an unrelated promoter, inhibited NF-kappaB nuclear binding.

CONCLUSIONS

Endotoxin tolerance and HS appear to share a common immune suppressive effect, possibly through HSF-1-mediated competitive inhibition of NF-kappaB nuclear binding.

Active hexose correlated compound activates immune function to decrease bacterial load in a murine model of intramuscular infection

BACKGROUND

Infection is a serious, costly, and common complication of surgery and constitutes the principal cause of late death in patients undergoing surgery. The objective of this study was to clarify the mechanisms by which active hexose correlated compound (AHCC) increases survival in a murine model of intramuscular infection.

METHODS

Food-deprived mice receiving either AHCC or excipient were infected with bacteria. Kinetics of bacterial load, white blood cell counts, cytokine levels, and antibody levels were compared between groups.

RESULTS

AHCC-treated mice had reduced bacterial load at day 5 and cleared bacteria entirely at day 6. Levels of interleukin-12, tumor necrosis factor-alpha, and interleukin-6 peaked earlier in this group (day 3) compared with controls (day 5). Increased percentages of peripheral lymphocytes and monocytes and decreased numbers of polymorphonuclear cells were detected in the AHCC group.

CONCLUSIONS

AHCC appears to induce an early activation of the immune response, leading to an effective clearance of bacteria and rapid recovery.

Active hexose correlated compound (AHCC) enhances resistance to infection in a mouse model of surgical wound infection

BACKGROUND

Infection is the most common postoperative complication within the surgical wound and during severe trauma. In spite of the use of modern sterile techniques and prophylaxis, infection continues to be a leading cause of death in these patients. Therefore, it has become crucial to develop new alternatives to prevent the effects of trauma and other complications on the immune system and improve resistance to infection. The objective of this study was to test the prophylactic effects of oral administration of active hexose correlated compound (AHCC), a natural immunoenhancer, on survival in a mouse model of surgical soft tissue infection.

METHODS

The model involves the intramuscular administration of a 50% lethal dose (LD50) of K. pneumoniae to mice that have restricted food intake for 24 hours prior to and six hours after infection and simulates local infection and food deprivation that often occur during trauma or surgical procedures. In the present study, AHCC was administrated orally to Swiss Webster mice for eight days prior to and during the infection period. Survival, time of death, LD50, and clearance of bacteria of this group were compared with those control mice receiving the excipient alone.

RESULTS

Survival and mean time to death were increased significantly in the AHCC-treated group; the LD50 was greater in mice receiving AHCC than in mice receiving the excipient. Mice receiving AHCC were better able to clear bacteria from their systems than were control animals.

CONCLUSIONS

The results suggest that AHCC protects mice in this model by restoring the immune and other systems negatively affected by trauma, infection, and food deprivation. More studies are necessary to determine the intrinsic mechanisms involved in this model and whether AHCC can prevent infection or improve survival in human beings with severe trauma or undergoing surgical procedures.

Use of intracellular cytokine staining and bacterial superantigen to document suppression of the adaptive immune system in injured patients

OBJECTIVE

To determine the percentages of major T lymphocyte subsets in the circulating peripheral blood mononuclear cell population in patients with major traumatic injury at early and late time points and to determine the expression of coreceptors and cytokine production by these T cell subsets.

SUMMARY BACKGROUND DATA

Prior studies suggest that serious injury in humans suppresses the adaptive immune system as revealed by diminished proliferation and altered cytokine production in response to polyclonal T cell activation. However, the contribution of individual cell types to this immune dysfunction has not been well characterized.

METHODS

The percentage of circulating CD4+ and CD8+ T cells and the relative density of CD4 and CD8 coreceptor expression was determined by flow cytometry in 17 consecutive trauma patients (injury severity score > 20) within 24 hours of injury and at day 7. Intracellular expression of the cytokines interleukin 2 (IL-2), interferon gamma (IFNgamma), IL-4, and IL-10 were also studied after stimulation with bacterial superantigen (SEB). Patients were compared with age- and sex-matched controls and to themselves for differences between early and late cytokine expression.

RESULTS

The percentage of circulating CD4+ and CD8+ T cells was decreased versus controls at day 1 and further decreased by day 7 following injury. CD4 and CD8 cell surface expression was also decreased at days 1 and 7. CD4+ T cells in injured patients responded to SEB activation with decreased expression of IFNgamma and IL-2 on day 1 versus controls (P < 0.05) and of all 4 cytokines by day 7 (P < 0.05), while CD8+ T cells showed diminished expression of IFNgamma and IL-2 only at both time points. When day 1 and day 7 cytokine expression results were compared in the same patients, CD4+ T cells showed diminished expression of IFNgamma, IL-2, and IL-4 by day 7 (P < 0.05), but maintained expression of IL-10. CD8 T cells showed diminished expression of IFNgamma only.

CONCLUSIONS

Severe injury induces a loss of circulating CD4+ and CD8+ T lymphocytes and diminished coreceptor expression by these cells. Both T cell subsets show progressive loss of immunostimulatory cytokine production with maintenance of potentially suppressive IL-10 production. These events may have negative consequences for host defense.

Infection control: avoiding the inevitable

Infection, while a major cause of morbidity, should not be considered an inevitable consequence of injury. Good aseptic technique, compulsive attention to detail, and thorough understanding of the points addressed in the following list of critical points are the best guarantee that infection will not add avoidable morbidity to misfortune. Critical points regarding infectious problems in care of the injured child: 1. Polymicrobial infection is the rule with 50% of isolates being mixed aerobic and anaerobic bacteria. 2. It is a misnomer to consider antibiotic use in a pediatric trauma victim as prophylactic. Antimicrobials used in this setting are best considered adjunctive. 3. The major indication for anti-infective therapy in pediatric trauma is an injury with a high probability of infection. 4. Antibiotics do not sterilize the wound or body cavity; they limit bacterial proliferation, thereby supplementing effective immune control. 5. Available studies suggest that 24 hours is as efficacious as a longer treatment duration in a purely adjunctive mode. 6. In bites inflicted by dogs and cats, Pasturella species are frequent. 7. Human bites may result in infection by Eikenella corrodens. 8. Based on this bacteriology, adjunctive intravenous ampicillin sulbactam or oral amoxicillin clavulanate are recommended for human and animal bites. 9. Tetanus prophylaxis is indicated in all significant soft tissue injuries. 10. Risk of osteomyelitis correlates directly with the extent of the associated soft tissue injury and vascular compromise. 11. The majority of infectious complications in the injured child are not a consequence of the injury itself, but rather in the treatment thereof. 12. In the injured child the most common nosocomial infection is lower respiratory followed by primary blood stream and the urinary tract. 13. The management of nosocomial pneumonia in the injured child is based on the time of diagnoses. Early evidence of pulmonary infection requires treatment with a third generation cephalosporin with or without an antistaphylococcal penicillin. Late pneumonia is treated with an aminoglycoside with or without an antipseudomonal added. 14. Catheter related infection is, in the injured child, overwhelmingly gram positive with coagulase negative staphlococcal species accounting for 30-60% of isolates. Staphlococcus aureus is responsible for an additional 15-20%. 15. The role of antibiotics in the prevention of catheter related meningitis is controversial. Recent adult studies suggest no advantage to their routine use. If utilized, they should only be employed prophylactically and not continued throughout the monitoring period. 16. Lack of response to treatment of sepsis may represent an inappropriate antimicrobial agent, improper dosage, inability to achieve adequate levels at the site of infection. (eg, CSF) fungal pathogen, and/or ongoing contamination or undrained purulent focus.

Inhibition of the Defense System Stimulating Interleukin-12 Interferon-γ Pathway During Critical Illness

Interleukin-12 (IL-12) and interferon-γ (IFN-γ) exert protective effects during experimental endotoxemia through upregulation of cellular immunity and phagocytic functions. They are part of a positive regulatory feedback loop that enhances the production of the other. Because critically ill patients show a marked suppression of T-cell and macrophage functions with a high susceptibility to infection, potential defects in the immunity/inflammation upregulating IL-12 IFN-γ pathway were studied. As an ex vivo model of endotoxemia, lipopolysaccharide (LPS) stimulated whole blood from 25 critically ill patients and 12 healthy individuals was incubated with either recombinant human (rh) IL-12 or rhIFN-γ, respectively. IFN-γ dose-dependently (P < .05) increased the release of IL-12 p40 and p70 into LPS-stimulated whole blood from healthy humans without effect in whole blood from critically ill patients. RhIL-12 p70 enhanced (P < .05) the secretion of IFN-γ in controls, while it was ineffective in LPS-stimulated whole blood from critically ill patients. The observed inhibition of the IL-12 IFN-γ pathway is not specific to LPS, since Staphylococcus aureus Cowan strain I (SAC)-stimulated whole blood from critically ill patients showed similar suppression. The secretion of IL-12 and IFN-γ was less reduced in critically ill patients when using isolated cultures of adherent cells or lymphocytes. Although preculture of whole blood from healthy humans with IL-10, but not with IL-4, mimicked suppression of the IL-12 IFN-γ pathway similar to that observed during critical illness, the release of antiinflammatory reacting cytokines (IL-4, IL-10, transforming growth factor [TGF]-β1 ) was decreased into LPS-stimulated whole blood from critically ill patients. These results indicate at least two mechanisms responsible for dramatic disturbances of the IL-12 IFN-γ pathway during critical illness: (1) deactivation of IL-12 and IFN-γ producing leukocytes in vivo early after the primary insult, and (2) presence of serum suppressive factors different from IL-4, IL-10, or TGF-β1 . Because IL-12 and IFN-γ upregulate essential immune functions, the marked inhibition of IL-12 and IFN-γ release may be pivotal for high susceptibility of critically ill patients to infection.

Inhibition of the Defense System Stimulating Interleukin-12 Interferon-γ Pathway During Critical Illness

Interleukin-12 (IL-12) and interferon-γ (IFN-γ) exert protective effects during experimental endotoxemia through upregulation of cellular immunity and phagocytic functions. They are part of a positive regulatory feedback loop that enhances the production of the other. Because critically ill patients show a marked suppression of T-cell and macrophage functions with a high susceptibility to infection, potential defects in the immunity/inflammation upregulating IL-12 IFN-γ pathway were studied. As an ex vivo model of endotoxemia, lipopolysaccharide (LPS) stimulated whole blood from 25 critically ill patients and 12 healthy individuals was incubated with either recombinant human (rh) IL-12 or rhIFN-γ, respectively. IFN-γ dose-dependently (P < .05) increased the release of IL-12 p40 and p70 into LPS-stimulated whole blood from healthy humans without effect in whole blood from critically ill patients. RhIL-12 p70 enhanced (P < .05) the secretion of IFN-γ in controls, while it was ineffective in LPS-stimulated whole blood from critically ill patients. The observed inhibition of the IL-12 IFN-γ pathway is not specific to LPS, since Staphylococcus aureus Cowan strain I (SAC)-stimulated whole blood from critically ill patients showed similar suppression. The secretion of IL-12 and IFN-γ was less reduced in critically ill patients when using isolated cultures of adherent cells or lymphocytes. Although preculture of whole blood from healthy humans with IL-10, but not with IL-4, mimicked suppression of the IL-12 IFN-γ pathway similar to that observed during critical illness, the release of antiinflammatory reacting cytokines (IL-4, IL-10, transforming growth factor [TGF]-β1 ) was decreased into LPS-stimulated whole blood from critically ill patients. These results indicate at least two mechanisms responsible for dramatic disturbances of the IL-12 IFN-γ pathway during critical illness: (1) deactivation of IL-12 and IFN-γ producing leukocytes in vivo early after the primary insult, and (2) presence of serum suppressive factors different from IL-4, IL-10, or TGF-β1 . Because IL-12 and IFN-γ upregulate essential immune functions, the marked inhibition of IL-12 and IFN-γ release may be pivotal for high susceptibility of critically ill patients to infection.

Toward a theory regarding the pathogenesis of the systemic inflammatory response syndrome: what we do and do not know about cytokine regulation

OBJECTIVES

The systemic inflammatory response syndrome (SIRS) is the massive inflammatory reaction resulting from systemic mediator release that may lead to multiple organ dysfunction. The objective of this review article is to analyze the roles of cytokines, cytokine production, and the relationship of cytokine production to the development of SIRS.

DATA SOURCES

Previous research and clinical studies related to cytokines and their relationship to SIRS.

STUDY SELECTION

From the studies reviewed, three critical questions are addressed. First, what is the definition of increased cytokine concentrations? Second, what other systemic illnesses besides sepsis can alter cytokine concentrations? Third, what are the right cytokines to measure?

DATA SYNTHESIS

This article postulates a three-stage development of SIRS, in which stage 1 is a local production of cytokines in response to an injury or infection. Stage 2 is the protective release of a small amount of cytokines into the body's circulation. Stage 3 is the massive systemic reaction where cytokines turn destructive by compromising the integrity of the capillary walls and flooding end organs.

CONCLUSIONS

While cytokines are generally viewed as a destructive development in the patient that generally leads to multiple organ dysfunction, cytokines also protect the body when localized. It will be necessary to study the positive effects of cytokines while also studying their role in causing SIRS. It will also be important to investigate the relationship between cytokines and their blockers in SIRS.

The effect of parenteral indomethacin on T-lymphocyte subpopulations and cytokine production in patients under major surgical operations

Major surgical trauma has been considered as a cause of immunosuppression mainly through the production of prostaglandin E2 from activated monocytes/macrophages. In the present study we investigated the effect of parenteral indomethacin--a cyclo-oxygenase inhibitor--on T-lymphocyte subsets and cytokine production in patients under major operations. We studied 20 patients undergoing major surgical procedures, 10 of whom were randomly treated pre- and post-operatively with indomethacin (group 2) and 10 were not (group 2). We measured total T-cells, T-helper, T-suppressor, T-helper/T-suppressor (Th/Ts) cell ratio, NK-cells and interleukin (IL-1) and tumor necrosis factor production by endotoxin- or phytohemagglutinin-stimulated peripheral blood mononuclear cells, before operation and at days 1, 3 and 7 postoperatively. We detected a significant increase in Th/Ts cell ratio and an improvement in delayed type hypersensitivity response in the treated group at day 3. We believe that the above immunomodulating effect of in vivo cyclo-oxygenase inhibition may be beneficial in patients under major surgical procedures with a high susceptibility to postoperative infections.

Pretreatment with enteral cholestyramine prevents suppression of the cellular immune system after partial hepatectomy

OBJECTIVE

The authors tested the hypothesis that the beneficial effects of the endotoxin-binding agent cholestyramine on the postoperative course in rats that had undergone a partial hepatectomy was the result of improvement of cellular immune functions.

SUMMARY BACKGROUND DATA

Major liver resection is associated with severe postoperative complications and a high incidence of systemic infections. Gut-derived endotoxins previously were shown to be involved in the pathogenic processes after partial hepatectomy in rats. In addition, enteral cholestyramine improved postoperative survival, but how its beneficial effects are mediated is not clear.

METHODS

Rats that were force-fed for 7 days with either cholestyramine (150 mg/day) or 0.9% saline (equal volume) were randomized to undergo a partial hepatectomy or a sham operation. After 24 hours, the rats were killed and splenic mononuclear cells were tested in vitro for mitogenic responses and cytokine production.

RESULTS

Proliferative responses of splenic B and T lymphocytes and lipopolysaccharide-stimulated production of tumor necrosis factor and interleukin-1 by splenocytes were lower in rats after partial hepatectomy than in sham-operated animals. An increased concanavalin A-stimulated production of interleukin-2 also was found after partial hepatectomy compared with sham levels. Pretreatment with enteral cholestyramine preserved cellular proliferative responsiveness of both B and T cells, and restored cytokine production by splenocytes to sham levels.

CONCLUSION

Prophylactic treatment with enteral cholestyramine preserved cellular immune functions after partial hepatectomy in the rat, which may explain its beneficial effects on the postoperative course. Furthermore, the authors' results are consistent with the hypothesis that endotoxemia is involved in the pathogenesis of the cellular immune derangements after partial hepatectomy.

Effect of ranitidine on soluble interleukin 2 receptors and CD8 molecules in surgical patients

The effect of perioperative immunomodulation with the H2-receptor antagonist ranitidine on postoperative changes in soluble interleukin (IL) 2 receptor and soluble CD8 levels was assessed in 24 patients undergoing major elective abdominal surgery. Eleven patients were randomized to receive intravenous ranitidine 100 mg twice daily for 4 days from skin incision, followed by oral ranitidine 150 mg twice daily for a further 5 days; 13 control patients received no ranitidine. Routine blood analysis, clinical data, duration of surgery, anaesthesia, antibiotic prophylaxis and perioperative blood transfusion were similar in the two groups. Serum concentrations of soluble IL-2 receptor and CD8 were measured before operation (day 0) and in the morning of postoperative days 1, 3 and 9 using commercial enzyme-linked immunosorbent assay kits. In patients treated with ranitidine, the serum level of soluble IL-2 receptor increased from day 0 to day 9 (P < 0.01); in control patients it decreased from day 0 to day 1, did not change significantly by day 3 and increased by day 9. The change from day 0 to day 1 was significantly different between the two groups (P < 0.01). Five of the 13 control patients developed postoperative infectious complications. No significant differences were shown in soluble CD8 concentration during the postoperative period. The postoperative change in soluble IL-2 receptor level may reflect lymphocyte activation status; ranitidine appears to promote activation of mainly CD4-positive lymphocytes since serum levels of CD8 were unchanged. Ranitidine may, therefore, improve immune function during major surgery.

Immunoglobulins and IgG subclasses in children following severe head injury

OBJECTIVE

To study immunoglobulin production after severe blunt head trauma in children.

DESIGN

Serum for IgG, IgM, IgA, IgE, and IgG subclasses were drawn from 10 children admitted with severe head injury (ISS 31.2, GCS 5.4) on day 1, 7, 14 and 21 after injury.

RESULTS

5 of the 10 patients developed infection between 7 and 14 days and 2 died of complications of pneumonia. On day 1, IgM levels averaged 95.6% of the mean of the age-specific normal controls. By day 7, IgM levels averaged 383% (p < 0.01). While all patients were within the age-specific normal range (+/- 2 SD) on day 1, 7 of 10 patients were above the normal range by day 7. There was no difference in IgM levels between infected and non-infected patients. Five patients were below the age-specific normal range for IgG on day 1, with 3 still low on day 7. By day 21, IgG levels averaged 141% of the mean of the age-specific normal controls. IgG subclasses followed a pattern similar to total IgG levels. Marked increases in IgE were seen in 3 patients.

CONCLUSIONS

IgM levels increased dramatically in all patients within seven days of the injury. While 50% of these children had a deficit of IgG in the first week, total IgG and IgA levels increased after injury, but not as rapidly as IgM levels. Unlike pediatric burn patients, there is no persistent hypogammaglobulinemia following severe blunt trauma in children.

Safety and efficacy of intravenous immunoglobulin prophylaxis in pediatric head trauma patients: a double-blind controlled trial

Infection is one of the major complications of severe head trauma in children. To assess whether intravenous immunoglobulin (IVIg) decreases the incidence of secondary infection after head injury in children, a randomized, double-blind trial was performed. Thirty-three children (mean age, 6.67 years; mean injury severity score, 32.8; mean Glasgow coma score, 6.1) with severe head injuries were enrolled; 1 child was excluded, 18 received IVIg, and 14 received the placebo preparation. Four hundred milligrams per kilogram of IVIg or albumin placebo was administered within 48 hours of admission. IgG levels were obtained before the infusion and then 1 week later. Patients were monitored for evidence of infection for the next 21 days. There was a 66% increase in mean IgG levels in the treatment group compared with 45% in the control group (P = .057). One death occurred in the IVIg group and two in the placebo group. No significant differences in the incidence of pneumonia, sepsis, presumed sepsis, or any other type of infection was noted. There was no difference in the number of days on mechanical ventilation or in number of hospital days. There were no side effects. It is concluded that prophylactic administration of commercial IVIg at a dose of 400 mg/kg, although safe, had no effect on the incidence of secondary infections in children with severe head injuries.

Effects of in vivo endotoxin infusions on in vitro cellular immune responses in humans

Studies of the immune response of patients following major injury have identified significant abnormalities, some of which may be due to the effects of endotoxin. To evaluate the effect of endotoxin on the immune system without conflicting variables, we studied 18 normal, healthy male volunteers each on two occasions. In one study, Escherichia coli endotoxin was administered intravenously at a dose of 4 ng/kg. In the other, saline was given. Blood for immune function studies was obtained at either 0, 4, or 24 hr (seven volunteers), 0, 1, and 4 hr (five volunteers), or 0, 4, and 6 hr (six volunteers) postinfusion. Peripheral blood mononuclear cells (PBMC) were isolated and adjusted to the same concentration. Measurements following endotoxin infusion were compared with those of the same volunteers following saline infusion and with those from normal ambulatory laboratory volunteers. Interleukin 1 (IL-1) production by adherent cells was significantly reduced at 1 hr post endotoxin infusion. Significant decreases in number of mononuclear cells, response to phytohemagglutinin (PHA), and production of IL-2 and IL-1 were observed by 4 hr after endotoxin infusion. No significant changes in percentages of monocytes, lymphocytes, or CD3, CD4, or CD8 lymphocytes were observed at any time. By 24 hr postinfusion all values had returned to normal or, in some cases, supranormal levels. Response to PHA by PBMC from volunteers 4 hr following endotoxin was completely restored by in vitro addition of recombinant human IL-2 but was only marginally improved by IL-1. In vitro addition of indomethacin to PBMC cultures responding to PHA reduced the suppression observed after in vivo endotoxin but also was not as effective as IL-2. In a fourth study, seven volunteers were treated as above either with two doses (800 mg each) of the cyclooxygenase inhibitor ibuprofen before endotoxin infusion or with ibuprofen alone. Ibuprofen pretreatment completely restored the PBMC response to PHA to normal and caused a significant decrease in the endotoxin-induced suppression of IL-2 production. However, the decrease in circulating PBMC number and adherent cell secretion of IL-1 was not affected by inhibition of the cyclooxygenase pathway. These results suggest that endotoxin has immunomodulatory effects on both adherent mononuclear-cell and T-lymphocyte function and that more than one mechanism is involved.

Immunosuppression in Trauma Patients

An immunosuppressed state develops following traumatic injury, which makes patients more prone to develop infection. A variety of disturbances accompany injury that affect both specific and nonspecific components of host defense. Many clinical studies have attempted to evaluate the many deficits that follow injury and place the patient at a higher risk for infection. Several components of host defense are affected simultaneously and include (1) cellular changes (decreased activation of T-lymphocyte subsets with decreased helper cells, increased suppressor T-cell function, increased but abnormal activity of macrophages, activation of polymorphonuclear leukocytes with depressed chemotaxis and killing); (2) depressed nonspecific and specific serum immunity (e.g., depressed fibronectin and immunoglobulin levels); (3) the presence of altered cytokine levels (interleukin-1 [IL-1], IL-2, IL-6, tumor necrosis factor) levels; (4) ongoing serum proteolytic activity; and (5) the generation of serum suppressive peptides. An in-depth understanding of the deficits that occur following injury in host defense will provide the basis for therapeutic intervention.

In vitro inhibition of IL-2 biosynthesis in activated human peripheral blood mononuclear cells by a trauma-induced glycopeptide

Traumatic injury often results in profound immunopathology that can lead to immunosuppression, thereby increasing the morbidity and mortality due to sepsis. The isolation and partial characterization of an immunosuppressive glycopeptide (SAP) from serum of severely burned patients has previously been reported by our laboratory. Recently, this trauma peptide has also been identified in the serum of patients with multiple blunt trauma. This glycopeptide is capable of suppressing neutrophil chemotaxis, T-cell blastogenesis and the lysis of human erythrocytes. We demonstrate in this report that SAP inhibits interleukin 2 (IL-2) biosynthesis by mitogen-stimulated peripheral blood mononuclear cells. Peptide concentrations of 50 nmol and above significantly inhibited IL-2 production. Inhibition was not reduced by the addition of indomethacin or anti-PGE2 to cultures containing greater than 100 nmol of peptide, suggesting that inhibition is not entirely prostaglandin-mediated. Preliminary studies have shown that IL-2 suppression by SAP can be partially reversed by the addition of calcium ionophore. These results suggest a potential immunosuppressive mechanism of the trauma peptide in which T cell blastogenesis is inhibited by interference in IL-2 biosynthesis.

In vitro studies of the role of monocytes in the immunosuppression associated with natural measles virus infections

Measles is associated with suppression of mitogen-induced proliferative responses. The role of monocytes in depressed responses to phytohemagglutinin during measles was assessed. Depleting peripheral blood mononuclear cells of adherent cells decreased, increased, and did not change proliferative responses in essentially equal numbers of individuals. Inhibition of prostaglandin synthesis by indomethacin significantly increased proliferation (P = 0.009) but often not to normal values. Addition of supplemental interleukin 1 had little effect. Addition of supplemental natural interleukin 2 significantly increased proliferation (P = 0.002) even in patients with very low responses. These data suggest that monocyte function is abnormal in some individuals with measles, that the abnormality is variable, and that lymphocyte response to monocyte signals is probably suboptimal as well.

Immature T lymphocytes after injury characterized by morphology and phenotypic markers

Changes in the peripheral blood mononuclear cell (PBMC) population in patients following both thermal and nonthermal injury were defined by both morphological characteristics and surface phenotype with the monoclonal antibodies T6, OKT9, OKT10, and OKIa1, using a fluorescence activated flow cytometer with gating to separate small cells of the lymphocyte series from larger forms. Lymphocytes with surface antigens that bind T6, OKT9, and OKT10 are rarely found in the peripheral blood of adult patients, except in those with malignancies of the lymphoid system. In both burn and trauma patients the percentage of lymphocytes in the PBMC population after Ficoll-Hypaque separation was significantly reduced as compared with normal controls due to increases in the number of granulocytes, large granular lymphocytes (LGL), and monocytes, often present in immature forms. T6 cells were found in significantly greater numbers in both burn and nonthermal injury patients than in a control group using both small and wide gate settings on the fluorescence-activated flow cytometer. Significant increases in the number of T9+ cells also were observed in both groups for a prolonged period following injury. Significantly increased numbers of the T10+ and Ia1+ cells were detected in burn patients. The response to injury, therefore, involves the appearance in the peripheral blood of immature cells that may express T6, T9, T10, and Ia1 surface antigens. These cells may be present in quantities otherwise seen only in malignant disease.