Alterations in immune function following head injury in children

Systems spatiotemporal dynamics of traumatic brain injury at single-cell resolution reveals humanin as a therapeutic target

BACKGROUND

The etiology of mild traumatic brain injury (mTBI) remains elusive due to the tissue and cellular heterogeneity of the affected brain regions that underlie cognitive impairments and subsequent neurological disorders. This complexity is further exacerbated by disrupted circuits within and between cell populations across brain regions and the periphery, which occur at different timescales and in spatial domains.

METHODS

We profiled three tissues (hippocampus, frontal cortex, and blood leukocytes) at the acute (24-h) and subacute (7-day) phases of mTBI at single-cell resolution.

RESULTS

We demonstrated that the coordinated gene expression patterns across cell types were disrupted and re-organized by TBI at different timescales with distinct regional and cellular patterns. Gene expression-based network modeling implied astrocytes as a key regulator of the cell-cell coordination following mTBI in both hippocampus and frontal cortex across timepoints, and mt-Rnr2, which encodes the mitochondrial peptide humanin, as a potential target for intervention based on its broad regional and dynamic dysregulation following mTBI. Treatment of a murine mTBI model with humanin reversed cognitive impairment caused by mTBI through the restoration of metabolic pathways within astrocytes.

CONCLUSIONS

Our results offer a systems-level understanding of the dynamic and spatial regulation of gene programs by mTBI and pinpoint key target genes, pathways, and cell circuits that are amenable to therapeutics.

Relationship between T-cell-dependent and T-cell-independent vaccines after neurotrauma; is the B-cell response preserved?

Background

After trauma and central nervous system (CNS) injury, trauma-induced immune deficiency syndrome (TIDS) and CNS injury-induced immune deficiency syndrome (CIDS) may negatively affect responses to T-cell-dependent vaccines, such as pneumococcal conjugate vaccine (PCV) recommended after basilar fracture. This study (NCT02806284) aimed to investigate whether there after neurotrauma is a correlation between T-cell-dependent and independent vaccine responses and, thus, if B-cell activity is similarly depressed and whether the T-cell-dependent response is possible to predict.

Methods

Adult patients with basilar fracture (n = 33) and those undergoing pituitary gland surgery (n = 23) were within 10 days vaccinated with a T-cell-dependent vaccine against Haemophilus influenzae type b (Hib) and a T-cell-independent pneumococcal polysaccharide vaccine (PPSV). Samples reflecting the systemic inflammatory response and pre- and post-vaccination antibody levels after 3–6 weeks against Hib and PPSV were collected and determined by enzyme immunoassays.

Results

High and significant correlations were detected in the responses to different pneumococcal serotypes, but none between the Hib and PPSV responses. No differences in trauma scores, C-reactive protein, IL-6, IL-10, pentraxin 3, fractalkine or calprotectin plasma concentrations or in ex vivo TNF-α, IL-6 or IL-10 responses to endotoxin were found between Hib vaccination responders and non-responders.

Conclusions

There was no correlation between the pneumococcal responses and that to Hib, indicating that B-cell function is not similarly depressed as T-cell function. Grading of the trauma or parameters reflecting the innate immune response could not predict the T-cell-dependent vaccine response. There is a need of further studies evaluating the vaccine response after neurotrauma.

Complications of external cerebrospinal fluid drainage in aneurysmal subarachnoid haemorrhage

Background

The need for external cerebrospinal fluid (CSF) drains in aneurysmal subarachnoid haemorrhage (aSAH) patients is common and might lead to additional complications.

Objective

A relation between the presence of an external CSF drain and complication risk is investigated.

Methods

A prospective complication registry was analysed retrospectively. We included all adult aSAH patients admitted to our academic hospital between January 2016 and January 2018, treated with an external CSF drain. Demographic data, type of external drain used, the severity of the aSAH and complications, up to 30 days after drain placement, were registered. Complications were divided into (1) complications with a direct relation to the external CSF drain and (2) complications that could not be directly related to the use of an external CSF drain referred to as medical complications

Results

One hundred and forty drains were implanted in 100 aSAH patients. In total, 112 complications occurred in 59 patients. Thirty-six complications were drain related and 76 were medical complications. The most common complication was infection (n = 34). Drain dislodgement occurred 16 times, followed by meningitis (n = 11) and occlusion (n = 9). A Poisson model showed that the mean number of complications raised by 2.9% for each additional day of drainage (95% CI: 0.6–5.3% p = 0.01).

Conclusion

Complications are common in patients with aneurysmal subarachnoid haemorrhage of which 32% are drain-related. A correlation is present between drainage period and the number of complications. Therefore, reducing drainage period could be a target for further improvement of care.

Cellular infiltration in traumatic brain injury

Traumatic brain injury leads to cellular damage which in turn results in the rapid release of damage-associated molecular patterns (DAMPs) that prompt resident cells to release cytokines and chemokines. These in turn rapidly recruit neutrophils, which assist in limiting the spread of injury and removing cellular debris. Microglia continuously survey the CNS (central nervous system) compartment and identify structural abnormalities in neurons contributing to the response. After some days, when neutrophil numbers start to decline, activated microglia and astrocytes assemble at the injury site—segregating injured tissue from healthy tissue and facilitating restorative processes. Monocytes infiltrate the injury site to produce chemokines that recruit astrocytes which successively extend their processes towards monocytes during the recovery phase. In this fashion, monocytes infiltration serves to help repair the injured brain. Neurons and astrocytes also moderate brain inflammation via downregulation of cytotoxic inflammation. Depending on the severity of the brain injury, T and B cells can also be recruited to the brain pathology sites at later time points.

Interaction Between 2 Nutraceutical Treatments and Host Immune Status in the Pediatric Critical Illness Stress-Induced Immune Suppression Comparative Effectiveness Trial

BACKGROUND AND AIMS

The pediatric Critical Illness Stress-induced Immune Suppression (CRISIS) trial compared the effectiveness of 2 nutraceutical supplementation strategies and found no difference in the development of nosocomial infection and sepsis in the overall population. We performed an exploratory post hoc analysis of interaction between nutraceutical treatments and host immune status related to the development of nosocomial infection/sepsis.

METHODS

Children from the CRISIS trial were analyzed according to 3 admission immune status categories marked by decreasing immune competence: immune competent without lymphopenia, immune competent with lymphopenia, and previously immunocompromised. The comparative effectiveness of the 2 treatments was analyzed for interaction with immune status category.

RESULTS

There were 134 immune-competent children without lymphopenia, 79 previously immune-competent children with lymphopenia, and 27 immunocompromised children who received 1 of the 2 treatments. A significant interaction was found between treatment arms and immune status on the time to development of nosocomial infection and sepsis ( P < .05) and on the rate of nosocomial infection and sepsis per 100 patient days ( P < .05). Whey protein treatment protected immune-competent patients without lymphopenia from infection and sepsis, both nutraceutical strategies were equivalent in immune-competent patients with lymphopenia, and zinc, selenium, glutamine, and metoclopramide treatment protected immunocompromised patients from infection and sepsis.

CONCLUSIONS

The science of immune nutrition is more complex than previously thought. Future trial design should consider immune status at the time of trial entry because differential effects of nutraceuticals may be related to this patient characteristic.

Inherent Risk Factors for Nosocomial Infection in the Long Stay Critically Ill Child Without Known Baseline Immunocompromise: A Post Hoc Analysis of the CRISIS Trial

BACKGROUND

Nosocomial infection remains an important health problem in long stay (>3 days) pediatric intensive care unit (PICU) patients. Admission risk factors related to the development of nosocomial infection in long stay immune competent patients in particular are not known.

METHODS

Post-hoc analysis of the previously published Critical Illness Stress induced Immune Suppression (CRISIS) prevention trial database, to identify baseline risk factors for nosocomial infection. Because there was no difference between treatment arms of that study in nosocomial infection in the population without known baseline immunocompromise, both arms were combined and the cohort that developed nosocomial infection was compared with the cohort that did not.

RESULTS

There were 254 long stay PICU patients without known baseline immunocompromise. Ninety (35%) developed nosocomial infection, and 164 (65%) did not. Admission characteristics associated with increased nosocomial infection risk were increased age, higher Pediatric Risk of Mortality version III score, the diagnoses of trauma or cardiac arrest and lymphopenia (P < 0.05). The presence of sepsis or infection at admission was associated with reduced risk of developing nosocomial infection (P < 0.05). In multivariable analysis, only increasing age, cardiac arrest and existing lymphopenia remained significant admission risk factors (P < 0.05); whereas trauma tended to be related to nosocomial infection development (P = 0.07).

CONCLUSIONS

These data suggest that increasing age, cardiac arrest and lymphopenia predispose long stay PICU patients without known baseline immunocompromise to nosocomial infection. These findings may inform pre-hoc stratification randomization strategies for prospective studies designed to prevent nosocomial infection in this population.

Bloodstream infections in NNICU: Blight on ICU stay

Background:

Bloodstream infections (BSIs) are among the serious hospital-acquired infections. Data regarding BSIs in intensive care units (ICUs) are available but there is limited information regarding these infections in neurology and neurosurgery intensive care units (NNICUs).

Objectives:

This study was conducted to find out the occurrence of BSI in NNICU patients of a tertiary care institute in India, along with the microbiological profile and risk factors associated with it.

Materials and Methods:

One hundred patients admitted in the NNICU of a tertiary care hospital for more than 24 h were included in the study. After detailed history, blood samples were collected from catheter hub and peripheral vein of all patients for culture, followed by identification and antibiotic sensitivity testing of the isolates.

Results:

Out of 100 patients, laboratory-confirmed bloodstream infection (LCBI) was detected in 16 patients. Five patients had secondary BSI, while 11 had central venous catheter (CVC)-related primary BSI. Gram-positive organisms constituted 64% of the isolates, especially coagulase-negative staphylococci and Staphylococcus aureus. Increased duration of CVC was a significant risk factor for catheter-related BSI (CR-BSI).

Conclusion:

BSIs pose a significant burden for NNICU patients, and increased duration of catheter insertion is a significant risk factor for CR-BSI.

Traumatic Brain Injury and Peripheral Immune Suppression: Primer and Prospectus

Nosocomial infections are a common occurrence in patients following traumatic brain injury (TBI) and are associated with an increased risk of mortality, longer length of hospital stay, and poor neurological outcome. Systemic immune suppression arising as a direct result of injury to the central nervous system (CNS) is considered to be primarily responsible for this increased incidence of infection, a view strengthened by recent studies that have reported novel changes in the composition and function of the innate and adaptive arms of the immune system post-TBI. However, our knowledge of the mechanisms that underlie TBI-induced immune suppression is equivocal at best. Here, after summarizing our current understanding of the impact of TBI on peripheral immunity and discussing CNS-mediated regulation of immune function, we propose roles for a series of novel mechanisms in driving the immune suppression that is observed post-TBI. These mechanisms, which have never been considered before in the context of TBI-induced immune paresis, include the CNS-driven emergence into the circulation of myeloid-derived suppressor cells and suppressive neutrophil subsets, and the release from injured tissue of nuclear and mitochondria-derived damage associated molecular patterns. Moreover, in an effort to further our understanding of the mechanisms that underlie TBI-induced changes in immunity, we pose throughout the review a series of questions, which if answered would address a number of key issues, such as establishing whether manipulating peripheral immune function has potential as a future therapeutic strategy by which to treat and/or prevent infections in the hospitalized TBI patient.

Phenotype and functions of B cells in patients with acute brain injuries

BACKGROUND

Brain injuries (BI) induce a state of systemic immunosuppression, leading to a high risk of pneumonia. In this pilot study, we investigated the status of B cell compartment in BI patients.

METHODS

A prospective observational study was performed in 2 intensive care units in a university hospital. Blood samples were collected in 14 patients at day 1 and day 7 after acute BI. The phenotype and the ability of B cells to secrete IL-10 were compared to 11 healthy volunteers (HV).

RESULTS

Among the circulating lymphocytes, the frequency of B cells was significantly higher in BI patients compared to HV (p<0.001). B cells from BI patients displayed an activated profil on day 7 after BI, reflected by a significantly higher proportion of CD27(+) memory (p=0.01) and CD27(+) IgD(-) switched memory B cells (p=0.02), as well as a significantly higher blood level of IgA (p=0.001) and IgM (p<0.001) as compared to day 1. The frequency of IL-10 secreting B cells (IL-10(+) B cells) on day 1 and day 7 was significantly lower in BI patients compared to HV (p<0.05). Interestingly, we observed that all BI patients with high frequency of IL-10(+) B cells on day 1 displayed an episode of pneumonia, and had a longer duration of mechanical ventilation and ICU stay compared to BI patients with low proportion of IL-10(+) B cells.

CONCLUSION

This study provides an extensive description of the phenotype and function of B cells in BI patients. Our results suggest that IL-10(+) B cells could play a major role in immunosuppression after BI.

Predictors of Nosocomial Bloodstream Infections Among Critically Ill Adult Trauma Patients

Objective:

To identify the independent predictors of nosocomial bloodstream infections (BSIs) among critically ill adult trauma patients.

Design:

A prospective, cohort design was used to study patients who met predetermined inclusion criteria. Basic descriptive and univariate statistical analyses were performed to identify unadjusted predictors. A forward stepwise multivariate logistic regression analysis was then conducted to identify independent predictors of nosocomial BSI.

Setting:

Level I university-affiliated shock trauma center.

Patients:

Three hundred sixty-one critically ill adult trauma patients, 55 of whom developed nosocomial BSIs (15.2%).

Results:

Data analysis of 45 variables indicated that only 9 were independent predictors of nosocomial BSI: presence of a chest tube, use of immunosuppressive agents, presence of microbial resistance, length of stay, presence of preexisting infection, percentage change of serum albumin levels, patient disposition, transfusion of 10 or more units of blood, and number of central venous catheters (CVCs) for patients who had 4 or more. The classification index of the final regression model at a cut-off point of 0.5 had a specificity of 97.4%, a sensitivity of 60%, a positive predictive value of 76.7%, a negative predictive value of 93%, and an overall precision of 91%.

Conclusion:

In this study, only 9 variables were independent predictors of nosocomial BSI. Our findings are specific to critically ill adult trauma patients and should be interpreted within the context of this particular population.

Predictors of Nosocomial Bloodstream Infections Among Critically Ill Adult Trauma Patients

Objective:

To identify the independent predictors of nosocomial bloodstream infections (BSIs) among critically ill adult trauma patients.

Design:

A prospective, cohort design was used to study patients who met predetermined inclusion criteria. Basic descriptive and univariate statistical analyses were performed to identify unadjusted predictors. A forward stepwise multivariate logistic regression analysis was then conducted to identify independent predictors of nosocomial BSI.

Setting:

Level I university-affiliated shock trauma center.

Patients:

Three hundred sixty-one critically ill adult trauma patients, 55 of whom developed nosocomial BSIs (15.2%).

Results:

Data analysis of 45 variables indicated that only 9 were independent predictors of nosocomial BSI: presence of a chest tube, use of immunosuppressive agents, presence of microbial resistance, length of stay, presence of preexisting infection, percentage change of serum albumin levels, patient disposition, transfusion of 10 or more units of blood, and number of central venous catheters (CVCs) for patients who had 4 or more. The classification index of the final regression model at a cut-off point of 0.5 had a specificity of 97.4%, a sensitivity of 60%, a positive predictive value of 76.7%, a negative predictive value of 93%, and an overall precision of 91%.

Conclusion:

In this study, only 9 variables were independent predictors of nosocomial BSI. Our findings are specific to critically ill adult trauma patients and should be interpreted within the context of this particular population.

Comparative analysis of assays for detection of cell-mediated immunity toward cytomegalovirus and M. tuberculosis in samples from deceased organ donors

Cell-mediated immunity assays could be valuable for risk assessment of organ donors, but no data exist on their feasibility in deceased donors. In this study, 105 deceased donors (52.3 ± 16.9 years) were screened at the time of organ procurement. Pathogen-specific stimulation was performed using a cytomegalovirus (CMV) lysate, tuberculin (purified protein derivative [PPD]) and soluble Mycobacterium tuberculosis-specific ESAT-6/CFP-10 proteins in combination with an in-house fluorescence-activated cell sorting (FACS) assay or commercial assay formats (QuantiFERON-CMV/TB for ELISA, T-SPOT.TB for ELISPOT). CMV-IgG antibody titers were determined as gold standard for CMV infection; 51.4% of samples were CMV seropositive. Indeterminate results were observed in 47.6% of ELISA, 12.5% of FACS and 0% of ELISPOT assays. Agreement with serology was highest for FACS (95.6%, κ = 0.91), followed by ELISPOT (84.0%, κ = 0.68) and ELISA (80.0%, κ = 0.60). Agreement between ELISA and serology increased if the CMV lysate was used as stimulus (96.7%, κ = 0.92). Among the T cell assays, agreement between ELISPOT and FACS was highest (κ = 0.70). PPD-positive results among valid samples differed between assays (26.5% for ELISA, 23.1% for FACS and 50.5% for ELISPOT); 2.0% were QuantiFERON-TB positive, 3.3% were ESAT-6/CFP-10-positive in FACS and 13.4% were positive in the T-SPOT.TB assay. In conclusion, cellular immunity may be analyzed from samples of deceased donors, although the assays differ in the rate of positivity and indeterminate results.

Traumatic brain injury-induced alterations in peripheral immunity

BACKGROUND

The complex alterations that occur in peripheral immunity after traumatic brain injury (TBI) have been poorly characterized to date. The purpose of this study was to determine the temporal changes in the peripheral immune response after TBI in a murine model of closed head injury.

METHODS

C57Bl/6 mice underwent closed head injury via a weight drop technique (n = 5) versus sham injury (n = 3) per time point. Blood, spleen, and thymus were collected, and immune phenotype, cytokine expression, and antibody production were determined via flow cytometry and multiplex immunoassays at 1, 3, 7, 14, 30, and 60 days after injury.

RESULTS

TBI results in acute and chronic changes in both the innate and adaptive immune response. TBI resulted in a striking loss of thymocytes as early as 3 days after injury (2.1 × 10 TBI vs. 5.6 × 10 sham, p = 0.001). Similarly, blood monocyte counts were markedly diminished as early as 24 hours after TBI (372 per deciliter TBI vs. 1359 per deciliter sham, p = 0.002) and remained suppressed throughout the first month after injury. At 60 days after injury, monocytes were polarized toward an anti-inflammatory (M2) phenotype. TBI also resulted in diminished interleukin 12 expression from Day 14 after injury throughout the remainder of the observation period.

CONCLUSION

TBI results in temporal changes in both the peripheral and the central immune systems culminating in an overall immune suppressed phenotype and anti-inflammatory milieu.

Impaired blood dendritic cell numbers and functions after aneurysmal subarachnoid hemorrhage

Previous Presentation

Portions of this study were presented at the Annual Congress of Société Française d’Anesthésie et de Réanimation in Paris, September 2012.

Background

Toll-like receptor (TLR) agonists are promising therapy for the prevention of nosocomial infections in critical ill patients. We aimed to analyze the TLR-reactivity of circulating dendritic cells (DC) as assessed by cytokine production after an ex vivo challenge with TLR agonists in aneurysmal subarachnoid hemorrhage (SAH) patients.

Methods and Findings

A single-center prospective observational study took place in one intensive care unit of a teaching hospital. Blood samples were harvested on days 2, 5 and 10 in 21 severe SAH patients requiring mechanical ventilation and 17 healthy controls. DC production of cytokines (Tumour Necrosis Factor, TNF-α; Interleukin, IL-12; and Interferon, IFN-α) was assessed by intracellular immunostaining on TLR-3, 4, 7/8 and 9 stimulations. SAH patients had decreased numbers of blood myeloid (mDCs) and plasmacytoid DCs (pDCs) on days 2, 5 and 10. Compared with the healthy controls, the frequency of mDCs producing TNF-α after TLR-3 stimulation was decreased in the SAH patients. The frequency of myeloid DCs producing IL-12 after TLR-3 and 4 stimulations was also decreased in the SAH patients. In contrast, the mDCs response to TLR-7/8 was not impaired in the SAH patients. The frequency of pDCs producing TNF-α⁺ and IFN-α⁺ on TLR-7/8 stimulation were reduced at all of the tested times in the SAH patients, whereas reactivity to TLR-9 was preserved. On day 2, the pDCs from non-survivor patients (n = 8) had a decreased ability to produce IFN-α on TLR-9 stimulation compared with the survivors.

Conclusions

These data suggest functional abnormalities of circulating pDCs and mDCs that could be important for immunomodulation after SAH.

Diagnosis and management of tuberculosis in transplant donors: a donor-derived infections consensus conference report

Mycobacterium tuberculosis is a ubiquitous organism that infects one-third of the world's population. In previous decades, access to organ transplantation was restricted to academic medical centers in more developed, low tuberculosis (TB) incidence countries. Globalization, changing immigration patterns, and the expansion of sophisticated medical procedures to medium and high TB incidence countries have made tuberculosis an increasingly important posttransplant infectious disease. Tuberculosis is now one of the most common bacterial causes of solid-organ transplant donor-derived infection reported in transplant recipients in the United States. Recognition of latent or undiagnosed active TB in the potential organ donor is critical to prevent emergence of disease in the recipient posttransplant. Donor-derived tuberculosis after transplantation is associated with significant morbidity and mortality, which can best be prevented through careful screening and targeted treatment. To address this growing challenge and provide recommendations, an expert international working group was assembled including specialists in transplant infectious diseases, transplant surgery, organ procurement and TB epidemiology, diagnostics and management. This working group reviewed the currently available data to formulate consensus recommendations for screening and management of TB in organ donors.

[Brain injury, immunity and infections]

Infections are a major cause of death and morbidity after acute injury of the central nervous system (CNS). Acute lesions of the CNS alter immune homeostasis contributing to the development of immunosuppression (IS), and making the bed of the infection. IS results in a decreased phagocytic functions of neutrophils and macrophages as well as monocyte deactivation (decreased capacity of antigen presentation to lymphocytes). The immune abnormalities occur very quickly and may last for weeks. The neurovegetative system is closely connected to the secondary lymphoid organs where cells of innate immunity receive information from injured organs inducing the long lasting adaptive immune response (immune synapse). The sympathetic system is critically involved in the IS through production of anti-inflammatory mediators like interleukin-10. This may prove important as all types of acute injury of the CNS can lead to direct damage to sympathetic centers. Specialized units of care for ischemic stroke, taking into account the risk of infection related to the IS, have improved the prognosis until 18th month after the initial damage of the SNC. It is now well recognized that the improved long-term prognosis is related with the secondary prevention of recurrent ischaemia as well as aggressive management of pulmonary infections. A better understanding of the pathophysiology of IS can be considered in the near future, opening the door to immunomodulatory therapeutic trials.

Impact of nosocomial infectious complications after subarachnoid hemorrhage

OBJECTIVE

Critically ill neurological patients are susceptible to infections that may be distinct from other intensive care patients. The aim of this study is to quantify the prevalence, risk factors, and effect on the outcome of nosocomial infectious complications in patients with subarachnoid hemorrhage (SAH).

METHODS

We studied 573 consecutive patients with SAH, identified the most prevalent infectious complications, and performed univariate analyses to determine risk factors for each complication. Multiple logistic regression models were constructed to calculate adjusted odds ratios for associated risk factors and to assess the impact of infectious complications on 3-month outcome as evaluated with the modified Rankin Scale.

RESULTS

The most prevalent nosocomial infections were pneumonia (n = 114, 20%), urinary tract infection (n = 77, 13%), bloodstream infection (BSI) (n = 48, 8%), and meningitis/ventriculitis (n = 28, 5%). Significant independent associations with pneumonia included older age, poor Hunt and Hess grade, intubation/mechanical ventilation, and loss of consciousness at ictus. Urinary tract infection was associated with female sex and central line use. BSI was also associated with central line use, and meningitis/ventriculitis was associated with the presence of intraventricular hemorrhage and external ventricular drainage (all P < 0.05). After adjustment for Hunt and Hess grade, aneurysm size, and age, pneumonia (adjusted odds ratio, 2.04; 95% confidence interval, 1.12-3.71; P = 0.020) and BSI (adjusted odds ratio, 2.51; 95% confidence interval, 1.14-5.56; P = 0.023) independently predicted death or severe disability at 3 months. Prolonged length of stay was significantly associated with all infection types (P < 0.001).

CONCLUSION

Pneumonia and BSI are common infectious complications of SAH and independently predict poor outcome. The implementation of infection-control measures may be needed to improve outcome after SAH.

Impact of oral hygiene on prevention of ventilator-associated pneumonia in neuroscience patients

Ventilator-associated pneumonia is one of the most frequent complications among critically ill patients. Growth of pathogenic bacteria in dental plaque may serve as the source of these infections. This performance improvement initiative evaluated an aggressive oral care approach to prevent the accumulation of plaque containing bacteria. Our data support the use of these oral care measures and deep oral-pharyngeal suctioning for the prevention of aspiration of oral contents.

Isolated head injury in children affects the neutrophil function and lymphocyte count

BACKGROUND

Outcomes of treatment of postinjury complications remain unsatisfactory and research continues into the impact of trauma on innate and acquired immunity. The aim of our study was to describe how head injury affects a child's immunity by measuring the neutrophil function and lymphocytes subsets.

METHODS

The peripheral blood of 16 children with head trauma (Glasgow Coma Score < or =9) was examined. The blood samples were collected on the first and on the seventh day after trauma. The production of reactive oxygen species (ROS), spontaneous and stimulated, the expression of CD11b, and the lymphocyte subpopulations were measured. The blood of healthy children was studied as control. The impact of endotracheal intubation on the examined parameters was analyzed as well.

RESULTS

Head trauma leads to the increase of leukocytosis; the total production of ROS by peripheral blood neutrophils does not change after head injury. Correction of the results according to the number of neutrophils revealed a significant decrease in ROS production by a single neutrophil. The expression of adhesion molecule CD11b did not change. Head injury in children causes the decrease of the total lymphocyte count, CD3, CD4, CD8, and natural killer cells count on both the first and the seventh postinjury day. On the seventh day the significant decrease of natural killer cells subset was observed. The CD4/CD8 ratio increased from 1.5 (the first day) to 2.5 (the seventh day). The intubation did not affect the examined parameters.

CONCLUSIONS

After head injury, total ROS production and adhesion molecule CD11b expression remained unchanged when compared with control. The study did not demonstrate evidence for neutrophil activation in patients with head injuries. The total lymphocyte count was found to be decreased and the composition of lymphocytes' subsets was deeply impaired.

Increased Intra-Abdominal, Intrathoracic, and Intracranial Pressure After Severe Brain Injury: Multiple Compartment Syndrome

OBJECTIVES

Fluid therapy and/or acute lung injury may increase intra-abdominal pressure (IAP) and intrathoracic pressure, thereby increasing intracranial pressure (ICP) after traumatic brain injury (TBI). Further fluid administration to support cerebral perfusion or increasing ventilatory support to treat acute lung injury further increases ICP. This can create a cycle that ultimately produces multiple compartment syndrome (MCS). Both decompressive craniectomy (DC) and decompressive laparotomy (DL) decrease ICP. DL can also decrease IAP and ICP. We evaluated the serial application of DC and DL to treat MCS.

METHODS

Data were analyzed for 102 consecutive patients with severe TBI who underwent DC alone to decrease ICP or in combination with DL to treat MCS.

RESULTS

All 102 patients sustained blunt injury. Seventy percent were men with a mean age of 29.5 years, an Injury Severity Score of 34.4, and admission Glasgow Coma Scale score of 7.1. Fifty-one patients had diffuse brain injury and 51 had mass lesions. Seventy-eight patients (76%) underwent DC alone. Twenty-four (22%) had both therapies for MCS. Fifteen patients had DC before DL and nine had DL before DC. Mean time between DC and DL was 3.4 +/- 6 days. The mean IAP before DL was 28 +/- 5 mm Hg. Twenty-four-hour cumulative mean intrathoracic pressure decreased significantly after DL in the MCS group (p = 0.01). Mean ICP decreased significantly after both DC and DL (p < 0.05).

CONCLUSION

Increased ICP may be from primary TBI or MCS. Patients with MCS have a higher Injury Severity Score, ICP, and fluid requirements, but no increase in mortality. Both DC and DL reduce ICP and can be used in sequence. MCS should be considered in multiply injured patients with increased ICP that does not respond to therapy.

Severe Human Traumatic Brain Injury, but Not Cyclosporin A Treatment, Depresses Activated T Lymphocytes Early after Injury

Severe traumatic brain injury (TBI) leads to an immunocompromised state responsible for an increased morbidity and mortality. Our understanding of the mechanisms responsible for this brain damage is incomplete. Damage maybe mediated by a complex cascade of neuroinflammation, and cytokine activation. In addition, translocation and accumulation of T cells in the brain parenchyma could take place and be related to detrimental effects. Our aims in this prospective randomized pilot study, were to detect the early effect of severe TBI upon cell-mediated immunity, to verify if early immunologic impairment correlates with neurologic outcome, and finally, to test the effect of early administration of iv infusion of cyclosporin A upon cell-mediated immunologic function. Forty-nine patients with severe TBI were studied. Thirty-six of these patients received a 24-h intravenous infusion of Cyclosporin A, or two 24-h infusions of the drug. 10 patients were in the placebo group. Three patients, not enrolled in the cyclosporin trial, were studied only for the relationship between cellular immunity, neurological outcome, and infection rate. T cell counts and microbiological cultures were performed in all patients. Sixty-five percent of patients demonstrated reduced T lymphocyte counts on admission. Furthermore, reduction of T cell numbers was related with significantly worse neurologic outcome and an increase in pulmonary infection. There was no significant difference between the placebo and CsA treated patients for the studied immunological parameters, or for incidence of infection. We also observed sequestration/diapedesis of T cells into the brain parenchyma, around contusions, after human TBI and we speculate that this could be responsible for further brain damage.

Guillain–Barré syndrome following facial bone fracture

Guillain-Barré syndrome (GBS) is an inflammatory disorder of the peripheral nerves and nerve roots characterised by lymphocytes and macrophage infiltration and myelin destruction. Two-thirds of cases of GBS emerge from viral or bacterial infection. GBS following facial bone fracture is rare. This article discusses a case of classical GBS following facial bone fracture and its correlative mechanism. The association of GBS with head injury per se is not well recognised. This case highlights the possibility of GBS following facial bone fracture and indicates that medical staff should be alerted to the association.

Simultaneous aberrations in MØ and T cell function adversely affect trauma patients' clinical outcome: A possible faulty IL-13 feedback loop

Possible defective trauma patients' Mphi-T-cell feedback interactions between T cell IL-13 production and IL-1beta and IL-18 Mphi secretion were assessed. Mphi produced IL-1 and IL-18 augment T cell IL-13, which in turn limits excessive macrophage activation. Immunodepressed patients' T cells (depressed proliferation to alphaCD3 + alphaCD4) had decreased IL-13 production concomitant to aberrant Mphi activities ( upward arrow mTNFalpha, downward arrow IL-10) and consequent multiple organ failure (MOF). Decreased IL-13 levels in patients' T cell and diminished Mphi supernatant augmentation of healthy controls' T cell IL-13 production appeared concomitantly, suggesting patients' aberrant monokine levels might intensify in vivo T cell dysfunction severity. Patients' Mphi supernatants, which failed to augment controls' T cell IL-13 production, had depressed IL-1beta and lower induction of IL-18 than immunocompetent patients' Mphi, but combined addition of IL-1beta and IL-18 restored these Mphis' IL-13 enhancing activity. These data suggest that immunodepressed patients' aberrant monokine and depressed T cell IL-13 production are independent but synergistic contributors to emergence of MOF.

Central nervous system injury-induced immune deficiency syndrome

Infections are a leading cause of morbidity and mortality in patients with acute CNS injury. It has recently become clear that CNS injury significantly increases susceptibility to infection by brain-specific mechanisms: CNS injury induces a disturbance of the normally well balanced interplay between the immune system and the CNS. As a result, CNS injury leads to secondary immunodeficiency - CNS injury-induced immunodepression (CIDS) - and infection. CIDS might serve as a model for the study of the mechanisms and mediators of brain control over immunity. More importantly, understanding CIDS will allow us to work on developing effective therapeutic strategies, with which the outcome after CNS damage by a host of diseases could be improved by eliminating a major determinant of poor recovery.

Surveillance of nosocomial infections in a neurologic intensive care unit

OBJECTIVE

To assess data on the epidemiology of nosocomial infection (NI) among neurologic intensive care patients.

DESIGN

Prospective periodic surveillance study.

SETTING

An 8-bed neurologic intensive care unit (ICU).

PATIENTS

All those admitted for more than 24 hours during five 3-month periods between January 1999 and March 2003.

METHODS

Standardized surveillance within the German infection surveillance system.

RESULTS

Three hundred thirty-eight patients with a total of 2,867 patient-days and a mean length of stay of 8.5 days were enrolled during the 15-month study period. A total of 71 NIs were identified among 52 patients. Urinary tract infections (UTIs) were the most frequent NI (36.6%), followed by pneumonia (29.6%) and bloodstream infections (BSIs) (15.5%). The overall incidence and incidence density of NIs were 21.0 per 100 patients and 24.8 per 1,000 patient-days, respectively. Incidence densities were 9.8 UTIs per 1,000 urinary catheter-days (CI95, 6.4-14.4), 5.6 BSIs per 1,000 central venous catheter-days (CI9s, 2.8-10.0), and 12.8 cases of pneumonia per 1,000 ventilation-days (Cl95, 8.0-19.7). Device-associated UTI and pneumonia rates were in the upper range of national and international reference data for medical ICUs, despite the intensive infection control and prevention program in operation in the hospital.

CONCLUSION

Neurologic intensive care patients have relatively high rates of device-associated nosocomial pneumonia and UTI. For a valid comparison of surveillance data and implementation of targeted prevention strategies, we would strongly recommend provision of national benchmarks for the neurologic ICU setting.

Influence of gender and age on T-cell responses in a murine model of trauma-hemorrhage: differences between circulating and tissue-fixed cells

Clinical studies indicate that peripheral blood lymphocyte functions are depressed following trauma; however, it is unclear whether tissue-fixed lymphocyte functions are also altered under those conditions. Moreover, the impact of gender and age on peripheral T-cell responses following trauma-hemorrhage (TH) are unknown. To study this, immature (approximately 3 wk of age), mature (approximately 7 wk of age), and aged (approximately 23 mo of age) male and proestrus female C3H/HeN mice were sham operated or subjected to trauma (i.e., midline laparotomy) and hemorrhagic shock (30+/-5 mmHg for 90 min). Twenty-four hours after resuscitation, blood and splenocytes were harvested and T-cell functions assessed. In immature animals, TH induced an enhanced immune response in the splenic compartment and a suppressed response in the peripheral blood mononuclear cells (PBMC) that was independent of gender. Differential responses were observed in cells from mature mice. Splenic responses were enhanced following TH, independent of gender, whereas PBMC displayed gender dimorphism with suppressed proliferation and T-cell helper 1 responses in males but not in females. A similar pattern was observed in cells from aged mice. Splenic T cells from male mice displayed a suppressed CD4-to-CD8 ratio after TH, whereas no such change was observed in cells from proestrus females. In contrast, only PBMC from mature males displayed a suppressed CD4-to-CD8 ratio after TH. Thus gender differences exist in PBMC responses after TH that do not necessarily correlate with changes in the tissue-fixed compartment. Age is also an important factor in the immune responses after TH. In view of this, both gender and age should be taken into consideration in evaluating the immune status and in treatment of TH shock.

Nosocomial infections and immunity: lesson from brain-injured patients

Of brain-injured patients admitted to intensive care units, a significant number acquires nosocomial infections. Increased susceptibility to infectious agents could, at least partly, be due to transient immunodepression triggered by brain damage. Immune deficiency in patients with severe brain injury primarily involves T cell dysfunction. However, humoral and phagocytic deficiencies are also detectable. Activation of the hypothalamo-pituitary-adrenal axis and the sympathetic nervous system plays a crucial role in brain-mediated immunodepression. In this review we discuss the role of immunodepression in the development of nosocomial infections and clinical trials on immunomodulation in brain-injured patients with hospital-acquired infections.

Clinical challenges of nosocomial infections caused by antibiotic-resistant pathogens in pediatrics

Antibiotic resistance in nosocomial infections is an ever-increasing problem as health care institutions provide care for children with more complicated medical and surgical problems. Several mechanisms of antibiotic resistance are reviewed for both gram-negative and gram-positive nosocomial pathogens. These adaptive resistance mechanisms allow organisms to survive in an environment of extensive antibiotic use and result in clinically significant infections. Mobile genetic elements have facilitated the rapid spread of antibiotic resistance within and among species. The clinical challenge faced by many practitioners is to understand these mechanisms of antibiotic resistance and to develop strategies for successfully treating infection caused by resistant pathogens. Nosocomial outbreaks caused by resistant organisms are described, and an approach to empiric therapy based on presumed pathogens, site of infection, and local resistance patterns is discussed.

Prevention of nosocomial lower respiratory tract infections in patients after intracranial artery aneurysm surgery with a short course of antimicrobials

Nosocomial infections at a department of neurosurgery were followed prospectively. In 1999, a high incidence of nosocomial lower respiratory tract infections (NLRTI) was observed in patients after intracranial artery aneurysm surgery (ICAAS). From February to December 2000, a short course of ciprofloxacin and co-trimoxazole was given prophylactically to all patients with ICAAS. The incidence of nosocomial infections in patients after ICAAS fell from 78.4 to 30.9% (P<0.0001). The incidence of NLRTI fell from 43.3 to 13.6% (P<0.0001) and the incidence of urinary tract infections from 12.4 to 2.5% (P=0.015). No significant change in antibiotic sensitivity at the department was observed. Antibiotic use decreased from 100.4 defined daily doses (DDD) to 85.4 DDD per 100 bed-days.

Early immunological defects in comatose patients after acute brain injury

Object. The aim of this prospective study was to evaluate the phagocytic, humoral, and cellular arms of the immune system in comatose patients shortly after severe brain injury and to compare the findings with those reported earlier in patients in a persistent vegetative state. The study was conducted in intensive care units and immunology laboratories of university-affiliated hospitals in central Israel.

Methods. The study group consisted of 14 men aged 16 to 65 years who were comatose as a result of acute brain injury due to mechanical trauma. All were studied within 72 hours of injury. Brain damage was severe in all cases (Glasgow Coma Scale score < 8). Healthy age- and sex-matched volunteers served as simultaneous controls.

Infections arose in nine (75%) of the 12 patients in whom data were available; the cumulative mortality rate was 38% (five of 13 patients in whom outcome data were available). Every patient exhibited one or more defects in at least one arm of the immune system. Significant deficiencies were noted in neutrophil superoxide release, immunoglobulin (Ig)G, IgG1, IgM, C1q, C2, properdin, alternate C pathway, T cells, T helper cells, T suppressor cells, and natural killer cells. In an earlier series of patients examined by the authors months after the primary insult, these impairments were absent in most of the patients in the vegetative state.

Conclusions. Significant deficiencies of the immune system, particularly the cellular arm, are precipitated by severe brain injury within 72 hours of the event. These impairments probably play a role in the high rate of complicating infections and multiple organ failure. Together with earlier findings, the results of this study indicate that if brain-injured patients survive these hazards, their immune system will eventually recover.

Nucleosomes are major T and B cell autoantigens in systemic lupus erythematosus

OBJECTIVE

Double-stranded DNA (dsDNA) is a well-known target of autoantibodies in systemic lupus erythematosus (SLE). The majority of these autoantibodies are of the IgG isotype and show affinity maturation, both of which are known hallmarks of T cell help. T cell responses to autoantigens, including DNA, have been reported only incidentally in SLE patients. Nevertheless, in murine SLE, naked DNA and complexed DNA (nucleosomes) are known to be recognized by T cells. This study aimed to characterize the antinucleosome response and its clinical impact on human SLE.

METHODS

Nucleosomes were prepared from chicken erythrocytes. Sera from SLE and control patients were investigated by enzyme-linked immunosorbent assay (ELISA) for nucleosome-specific antibody responses. Peripheral blood mononuclear cells (PBMC) from SLE and control patients were analyzed by a kinetic T cell proliferation assay. PBMC were subsequently analyzed for nucleosome-specific T cell proliferation.

RESULTS

Of 136 SLE patients, 56% were seropositive for antinucleosome antibodies. In contrast, only 3% of 309 control patients (with rheumatoid arthritis, mixed connective tissue disease, undifferentiated connective tissue disease, Lyme borreliosis, scleroderma, Sjögren's syndrome, ulcerative colitis, hepatitis B virus infection, or human immunodeficiency virus infection) were seropositive. Thus, the antinucleosome ELISA had a sensitivity of 56%, a specificity of 97%, and a diagnostic confidence of 90% when applied to SLE. It was therefore superior to an anti-DNA ELISA that demonstrated a 69% diagnostic confidence in the same population. Antinucleosome reactivity in SLE patients correlated significantly with disease activity (P < 0.0001), nephritis (P < 0.002), and psychosis (P < 0.02). When proliferation assays were applied, 14 of 26 SLE patients (54%) were positive for nucleosome-specific T cells that proliferated in response to their cognate antigen. A suppressed response was elicited in 3 SLE patients (12%); in these patients, the PBMC response to nucleosomes was lower than the proliferation of PBMC in the presence of culture medium only. PBMC from the remaining 9 SLE patients (35%) were nonresponsive to nucleosomes in either way. Responding, nonresponding, and suppressed populations differed from each other significantly (P < 0.0001). None of the PBMC from 7 healthy donors and 10 control patients could be stimulated with nucleosomal antigens.

CONCLUSION

We present evidence that nucleosomes are major autoantigens in human SLE and that antinucleosomal antibodies are highly specific for the disease. The antinucleosome ELISA has been shown to be superior to the anti-dsDNA ELISA and may thus be a significantly better tool for diagnosing SLE. Nucleosome-specific T cells in SLE patients may help B cells class switch to IgG and undergo affinity maturation.

Release of proinflammatory cytokines by mitogen-stimulated peripheral blood mononuclear cells from critically ill multiple-trauma victims

This study investigated the alterations in circulating proinflammatory cytokines and cytokine production by peripheral blood mononuclear cells (PBMCs) in response to lipopolysaccharide (LPS) or phytohemagglutinin (PHA) after severe trauma. Plasma and PBMCs were collected from 17 severely injured trauma patients and 10 healthy subjects. Plasma was stored at -80 degrees C and analyzed for cytokines. Isolated PBMCs from each subject were stimulated with LPS or PHA and incubated at 5% CO2 for 24 hours. Supernatants were collected and analyzed for cytokines. There was no significant change in the plasma concentration of free TNF-alpha and IL-1beta between healthy subjects and trauma patients. Plasma IL-6, total TNF-alpha, and total IL-1beta were significantly increased in severely traumatized patients compared with healthy control subjects. PBMCs from trauma patients produced higher levels of TNF-alpha in response to LPS but it showed no significant change in IL-1beta and IL-6 production in response to PHA or LPS in comparison to PBMCs from control subjects. We conclude that severe trauma results in a significant increase in plasma proinflammatory cytokine IL-6. Free TNF-alpha and IL-1beta in plasma remain at levels comparable to those in uninjured controls, while plasma free IL-6 levels in trauma patients remain high. Serious injury is associated with an enhanced production of TNF-alpha by PBMCs stimulated with LPS.

Effect of prophylactic administration of recombinant human granulocyte colony-stimulating factor (filgrastim) on the frequency of nosocomial infections in patients with acute traumatic brain injury or cerebral hemorrhage. The Filgrastim Study Group

OBJECTIVE

To determine whether the use of prophylactic recombinant human granulocyte colony-stimulating factor (filgrastim) reduces the frequency of nosocomial infections in patients with either acute traumatic brain injury or cerebral hemorrhage.

DESIGN

Randomized, placebo-controlled, double-blind, multicenter phase II study.

SETTING

Intensive care units of seven medical centers.

PATIENTS

Patients with either acute traumatic brain injury or cerebral hemorrhage who were intubated within 6 hrs of admission and who were expected to be ventilated for >72 hrs.

INTERVENTIONS

Patients were randomized to receive daily subcutaneous injections of placebo (n = 21) or one of two doses of filgrastim (75 microg [n = 20] or 300 microg [n = 20]) for 10 days or until the absolute neutrophil count was >75,000 cells/mm3 or until extubation.

MEASUREMENTS AND MAIN RESULTS

End points included increase in absolute neutrophil count, safety of filgrastim, and frequency of nosocomial infections (pneumonia, bacteremia, and urinary tract infection). Filgrastim caused a dose-dependent increase in absolute neutrophil count. There were no differences in the frequency of pneumonia or urinary tract infection; however, there was a dose-dependent decrease in the frequency of bacteremias (p < .05). Adverse events were similar among the three groups. There was one case of acute respiratory distress syndrome in the placebo group.

CONCLUSION

In this patient population, use of filgrastim was safe and the agent appeared to reduce the risk of primary bacteremias but had no beneficial effects on mortality, length of stay, or other nosocomial infections.

Immunological and endocrinological disturbances in patients after prolonged coma following head injury

It has been previously reported that following severe brain damage, a deficit of cellular immunity could be detected in the early phase after the occurence of the lesion. We report here the results of a cross-sectional study on long term effects of severe brain damage on immunological and neuro-endocrine changes in patients who recovered from prolonged coma caused by head injury. Results obtained from post-comatose (PC) patients were compared with those obtained from two control groups made up of spinal-cord injury (SCI) patients and healthy subjects, respectively. The following parameters were studied: lymphomonocyte subsets; interleukin 2 (IL-2) production; natural killer (NK) activity and serum levels of adrenocorticotrophic hormone (ACTH), cortisol, follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin, tri-iodothyronine (T3) and thyroxine (T4). With respect to healthy controls the PC1 subgroup, i.e. patients examined 3-6 months after injury, showed a statistically significant decrease in IL-2 production, NK activity and CD25+ lymphocytes. Similar immunological disturbances were observed in SCI but not in the PC2 subgroup, i.e. patients examined later than 6 months after injury. The same sub-group of PC1 patients showed high serum levels of cortisol and PRL. These results could be related to the immunological status and may be interpreted as a transient but prolonged condition of chronic stress or "chronic alarm reaction". Copyright Rapid Science Ltd

Guillain-Barré syndrome and head trauma. Case report

The authors report the case of a 29 years old male patient presenting classical Guillain-Barré syndrome following head trauma. Only one other similar case is described in the literature. Head trauma as a precipitating event of the disease is discussed.

Anterior pituitary function during critical illness and dopamine treatment

OBJECTIVE

To summarize the available data on anterior pituitary function in critical illness and to focus on the endocrine effects of dopamine infusion. The analogy with anterior pituitary function in the elderly is highlighted, and the potential importance of these observations for recovery from critical illness is discussed.

DATA SOURCES

Computerized search of published research and reference list review.

STUDY SELECTION

Review of 178 citations. Included are seven original studies on the effect of dopamine on pituitary function in adult and pediatric critical illness performed by the authors.

DATA EXTRACTION

Studies on the endocrinology of illness, chronic stress, aging, and dopamine, or on the clinical importance of endocrine changes.

DATA SYNTHESIS

The different pituitary axes are important determinants of normal anabolism and immune function. Continuously increased serum cortisol concentrations, insulin resistance, blunted prolactin release, and attenuated pulsatility of growth hormone and luteinizing hormone secretory patterns, as well as multiple anomalies in the thyroid axis, characterize the endocrine profile of prolonged critical illness. Dopamine, a natural catecholamine with hypophysiotropic properties, which has been used for more than two decades as an inotropic and vasoactive drug in intensive care, suppresses the circulating concentrations of all anterior pituitary-dependent hormones, except for cortisol. Available evidence suggests that the major effect of dopamine administration on the endocrine system is unlikely to be beneficial for the threatened metabolic and immunologic homeostasis of the severely ill patient. This pattern of hypopituitarism induced by chronic, severe illness and exogenous dopamine administration is reminiscent of the hormonal profiles obtained in experimental models of chronic stress, suggesting that endogenous dopamine may play a role in the endocrine and metabolic response to critical illness.

CONCLUSIONS

The dopamine-induced or aggravated pituitary dysfunction in critical illness warrants caution with prolonged infusion of this catecholamine as a so-called supportive agent, particularly in early life. The potential of combined hormonal therapy to improve the metabolic and immune status of the critically ill patient deserves thorough investigation.

Elevated transforming growth factor-beta concentration correlates with posttrauma immunosuppression

OBJECTIVE

To determine whether trauma induces an increase in the concentration of circulating transforming growth factor-beta (TGF-beta), and whether there is a temporal correlation between plasma TGF-beta concentration and the development of posttrauma cellular immunosuppression.

MATERIALS AND METHODS

Male Sprague-Dawley rats were anesthetized, subjected to bilateral femur fractures or sham injury, and killed 1, 3, or 5 days later. Plasma TGF-beta levels, splenocyte phenotypes, mitogen-induced proliferation, interleukin-2 (IL-2) production, and IL-2 receptor (IL-2R) expression were determined at each time point.

MEASUREMENTS AND MAIN RESULTS

Splenocyte proliferation increased on day 1 postinjury without corresponding change in IL-2 or plasma TGF-beta levels. Splenocyte proliferation and IL-2 production were suppressed on day 3 postinjury, while plasma TGF-beta levels peaked. No differences were observed between trauma and control groups on day 5. Splenocyte phenotypes and IL-2R expression were similar in injured and control rats at all times.

CONCLUSIONS

Suppression of lymphocyte proliferation and IL-2 production after trauma occurs concomitantly with a rise in plasma TGF-beta. The immune response is restored with normalization of TGF-beta concentration. These observations suggest that TGF-beta may contribute to posttrauma immunosuppression.