Changes in mitogen responsiveness lymphocyte subsets after traumatic injury: relation to development of sepsis

Multi-institutional analysis of neutrophil-to-lymphocyte ratio (NLR) in patients with severe hemorrhage: A new mortality predictor value

BACKGROUND

The neutrophil/lymphocyte ratio (NLR) has been associated as a predictor for increased mortality in critically ill patients. We sought to determine the relationship between NLR and outcomes in adult trauma patients with severe hemorrhage requiring the initiation of massive transfusion protocol (MTP). We hypothesized that the NLR would be a prognostic indicator of mortality in this population.

METHODS

This was a multi-institutional retrospective cohort study of adult trauma patients (≥18 years) with severe hemorrhage who received MTP between November 2014 and November 2015. Differentiated blood cell counts obtained at days 3 and 10 were used to obtain NLR. Receiver operating characteristic (ROC) curve analysis assessed the predictive capacity of NLR on mortality. To identify the effect of NLR on survival, Kaplan-Meier (KM) survival analysis and Cox regression models were used.

RESULTS

A total of 285 patients with severe hemorrhage managed with MTP were analyzed from six participating institutions. Most (80%) were men, 57.2% suffered blunt trauma. Median (IQR) age, Injury Severity Score, and Glasgow Coma Scale were 35 (25-47), 25 (16-36), and 9 (3-15), respectively. Using ROC curve analysis, optimal NLR cutoff values of 8.81 at day 3 and 13.68 at day 10 were calculated by maximizing the Youden index. KM curves at day 3 (p = 0.05) and day 10 (p = 0.02) revealed an NLR greater than or equal to these cutoff values as a marker for increased in-hospital mortality. Cox regression models failed to demonstrate an NLR over 8.81 as predictive of in-hospital mortality at day 3 (p = 0.056) but was predictive for mortality if NLR was greater than 13.68 at day 10 (p = 0.036).

CONCLUSIONS

NLR is strongly associated with early mortality in patients with severe hemorrhage managed with MTP. Further research is needed to focus on factors that can ameliorate NLR in this patient population.

LEVEL OF EVIDENCE

Prognostic study, level III.

Hyporesponsiveness in leukocytes in sepsis: in vitro models reveal paradoxical effects of IL-10

Sepsis syndrome is linked with a systemic inflammatory response syndrome (SIRS). This severe inflammation is associated with an immune suppression as illustrated by the reduced capacity of circulating leukocytes to produce cytokines in response to in vitro activation. Non-infectious SIRS such as trauma, burn, hemorrhage or major surgery is also associated with a suppression of the immune system. This phenomenon has been recently termed CARS for compensatory anti-inflammatory response syndrome. We report in vitro experiments which suggest that a well-known anti-inflammatory cytokine, namely IL-10, may, in certain experimental conditions, prime the leukocytes finally leading to an increased cytokine production. We discuss the relevance of this in vitro model to the in vivo situations where immune suppression is limited to the blood compartment (or the hematopoietic organs) whereas, in inflammatory foci within the tissues, cytokine production is increased. Our data suggest that IL-10 may be a causative agent of concomitantly occurring SIRS and CARS.

Early assessment of leukocyte alterations at diagnosis of septic shock

A dramatic decrease in circulating lymphocyte number is regularly described after septic shock. However, it is unknown how early this alteration develops after diagnosis of shock and if it remains stable over time. Twenty-one septic shock patients with no comorbidities were included within 2 h after the beginning of vasopressive treatment. Flow cytometry phenotyping of circulating leukocyte subpopulations and quantitative real-time polymerase chain reaction of T-bet, GATA-3, FOXP3, and RORγ mRNA were performed in patients from the diagnosis of shock and every 6 h during the subsequent 48 h. From their admission in the intensive care unit, patients present with major alterations of circulating leukocyte count (leukocytosis, neutrophilia, and major lymphopenia). The numbers of every lymphocyte subpopulations (T, B, and natural killer cells) were diminished. Gene expression analysis of transcription factors specific for TH1, TH2, CD4CD25 regulatory, and TH17 lymphocytes showed a severe decrease in comparison with healthy individuals' values. These alterations remain stable during the first 48 h after inclusion in the protocol despite early and aggressive resuscitation and antibiotherapy administered in patients. At the time of diagnosis of shock and admission in the intensive care unit, septic patients already present with severe lymphopenia involving every lymphocyte subsets including CD4 T-cell subpopulations. No significant variation could be detected within the first 48 h. This should be taken into account in the forthcoming clinical trials testing immunomodulating therapies in septic shock patients.

Immunosuppression associated with interleukin-1R-associated-kinase-M upregulation predicts mortality in Gram-negative sepsis (melioidosis)

OBJECTIVES

Sepsis is associated with immunosuppression (characterized by a reduced capacity of circulating monocytes to release proinflammatory cytokines), which has been implicated in late mortality. Melioidosis, caused by the Gram-negative bacterium Burkholderia pseudomallei, is an important cause of community-acquired sepsis in Southeast Asia with a mortality of up to 40%. Previous in vitro and murine studies have suggested a key role for the so-called negative regulators of the toll-like receptor (TLR) signaling pathway in immunosuppression. In this study, we investigated the expression of these negative TLR regulators in patients with septic melioidosis in association with the responsiveness of peripheral blood leukocytes of these patients to lipopolysaccharide and B. pseudomallei.

DESIGN

Ex vivo study.

SETTING

Academic research laboratory.

PATIENTS

Thirty-two healthy controls and 34 patients with sepsis caused by B. pseudomallei.

INTERVENTIONS

None.

MEASUREMENTS

1) Plasma cytokine levels; 2) ex vivo cytokine production capacity of whole blood; and 3) purified mononuclear cell-derived messenger RNA (mRNA) levels of key inhibitory molecules of the TLR-signaling cascade were investigated.

MAIN RESULTS

In accordance with an immunosuppressed state, whole blood of patients demonstrated a strongly decreased capacity to release the proinflammatory cytokines tumor necrosis factor-[alpha], interleukin-1[beta], and the chemokine interleukin-8 after ex vivo stimulation with lipopolysaccharide or B. pseudomallei. Analysis of myeloid-differentiation-88-short, interleukin-1R-associated-kinase (IRAK)-M, IRAK-1, suppressor-of-cytokine signaling-3, Src-homology-2-domain-containing inositol-5-phosphatase-1, single-immunoglobulin-interleukin-1R-related-molecule, and A20 mRNA expression in purified mononuclear cells showed decreased IRAK-1 and elevated IRAK-M expression in patients with septic melioidosis. Immunosuppression was correlated with mortality; furthermore, patients who eventually died had higher IRAK-M mRNA levels on admission than the patients who survived.

CONCLUSIONS

Immunosuppression in sepsis caused by B. pseudomallei is associated with an upregulation of IRAK-M and an indicator of poor outcome.

Influence of vaccination and surgery on HLA-DR expression in patients with upper aerodigestive tract cancer

Major surgery is associated with an increased risk of post-operative immunosuppression and infections. We investigated the influence of influenza vaccination on cell-mediated immune responses in cancer patients undergoing either surgical or conservative therapy. Forty patients with an upper aerodigestive tract tumour were allocated to either a surgical or non-surgical treatment course. Patients within each group were randomized to the vaccination or non-vaccination group. Vaccination was performed twice before surgery or conservative treatment. Human leucocyte antigen receptor (HLA-DR) expression on monocytes was analysed by flow cytometry. In the surgical patients, HLA-DR expression on day 1 after surgery decreased in both the vaccinated and non-vaccinated groups. Vaccinated non-surgical patients showed significantly increased HLA-DR expression levels compared with the non-vaccinated patients. This pilot study demonstrated that vaccination increased monocyte HLA-DR expression in conservatively-treated cancer patients whereas surgery abrogated this response. Vaccination before surgery, therefore, might not help to maintain immune reactivity after surgery.

Postoperative serum attenuates LPS-induced release of TNF-alpha in orthopaedic surgery

Studies with ex vivo stimulation of whole blood samples from injured patients have revealed a diminished production capacity for a broad range of secretory products, including inflammatory cytokines. Recent interest has focused on the release of mediators in serum that depress the cell-mediated immune response following trauma. The involvement of the lipid mediator prostaglandin E2 (PGE2) has been assumed because it is a potent endogenous immunosuppressor. In the present study, we tested the hypothesis that inhibitory substances circulating in the patient's serum after a major musculoskeletal trauma might impair leukocyte function by evaluating the effect of such serum on cytokine release in a whole blood model. Six females and three males undergoing elective total hip replacement were included in the study. Ex vivo LPS-induced TNF-alpha and IL-10 were measured in whole blood sampled preoperatively and added serum taken before, at the end of operation, and at postoperative days 1 and 6 with saline as negative control. LPS induced significant releases of TNF-alpha and IL-10 in whole blood. Addition of preoperative, postoperative, and day-1 postoperative serum did not alter the LPS-induced release of TNF-alpha as compared to saline. In the presence of serum from postoperative day 6, however, the expression of TNF-alpha was significantly reduced as compared to saline and preoperative serum (p = 0.021 and 0.008, respectively). Neither of the serum samples altered the release of IL-10. PGE2 was significantly (p = 0.008) increased in serum at postoperative day 6 as compared to preoperative levels. In conclusion, these data show that at day 6 after major orthopaedic surgery, the patient serum contained activity that inhibited ex vivo LPS-induced TNF-alpha release. The potent TNF-alpha inhibitory activity found at day 6 after injury correlated with increased levels of PGE2 and indicates cell-mediated hyporesponsiveness to a second stimulus.

Up-regulation of MyD88s and SIGIRR, molecules inhibiting Toll-like receptor signaling, in monocytes from septic patients*

OBJECTIVE

Immune status is altered during systemic inflammatory response syndrome and sepsis. Reduced ex vivo tumor necrosis factor production has been regularly reported with lipopolysaccharide-activated monocytes. In this study, we addressed the specificity of this hyporeactivity and investigated some of the possible associated mechanistic events.

DESIGN

Ex vivo study.

SETTING

Academic research laboratory.

PATIENTS

Healthy controls, septic patients, and resuscitated patients after cardiac arrest (RCA). This latter group presents a systemic inflammatory response syndrome of noninfectious origin.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

We investigated the reactivity of patients' monocytes in terms of cytokine production, after stimulation with a Toll-like receptor (TLR) 2 (Pam3CysSK4), a TLR4 (lipopolysaccharide), a Nod2 agonist (muramyl dipeptide), or heat-killed bacteria. We also investigated the contribution of phagocytosis in cytokine production, studied the expression of intracellular bacterial peptidoglycan sensors (Nod1 and Nod2), and analyzed the messenger RNA expression of inhibitors of TLR signaling: Toll interacting protein (Tollip), suppressor of cytokine signaling-1 (SOCS1), myeloid differentiation 88 short (MyD88s), and single immunoglobulin interleukin-1 receptor-related molecule (SIGIRR). In sepsis, tumor necrosis factor production in response to lipopolysaccharide and Pam3CysSK4 was reduced, whereas interleukin-10 production was enhanced. The responsiveness to Staphylococcus aureus, Escherichia coli, and muramyl dipeptide and the expression of Nod1 and Nod2 were similar to those obtained for healthy donors. The messenger RNA expression of Tollip and SOCS1 was unchanged, whereas that of MyD88s and SIGIRR was significantly enhanced compared with healthy controls. Monocytes from RCA patients showed a reduced production of tumor necrosis factor in response to lipopolysaccharide but neither to Pam3CysSK4 nor to heat-killed bacteria. They displayed an increased expression of SIGIRR but not of MyD88s. We showed that TLR2-dependent nuclear factor-kappaB activation was inhibited by MyD88s but not by SIGIRR. This result may explain the normal tumor necrosis factor production through TLR2 observed for monocytes of RCA patients.

CONCLUSION

There is a "reprogramming" of monocyte reactivity, and not a global hyporeactivity, during systemic inflammation, which differs in septic and RCA patients.

Reprogramming of circulatory cells in sepsis and SIRS

Immune status is altered in patients with sepsis or non-infectious systemic inflammatory response syndrome (SIRS). Reduced ex-vivo TNF production by endotoxin-activated monocytes has been regularly reported. This observation is reminiscent of the phenomenon of endotoxin tolerance, and the term 'leukocyte reprogramming' well defines this phenomenon. This review will outline that the hyporesponsiveness of circulating leukocytes is not a generalized phenomenon in sepsis and SIRS. Indeed, the nature of the insult (i.e. infectious versus non-infectious SIRS; under anesthesia [surgery] or not [trauma, burn]), the nature of the activator used to trigger leukocytes (i.e. different Toll-like receptor ligands or whole bacteria), the nature of the cell culture (i.e. isolated monocytes versus peripheral blood mononuclear cells versus whole blood assays), and the nature of the analyzed cytokines (e.g. IL-1beta versus IL-1ra; TNF versus IL-10) have a profound influence on the outcome of the response.

Surgical trauma and immunosuppression: pathophysiology and potential immunomodulatory approaches

BACKGROUND

Several studies indicate that organ failure is the leading cause of death in the postoperative phase after major surgery. An excessive inflammatory response followed by a dramatic depression of cell-mediated immunity after major surgery appears to be responsible for the increased susceptibility to subsequent sepsis. In view of this, most of the scientific and medical research has been directed towards measuring the progression and interrelationship of mediators after major surgery. Furthermore, the effect of those mediators on cell-mediated immune responses has been studied.

OBJECTIVE

This article focuses on the effect of surgical injury and blood loss on cell-mediated immune responses in experimental studies utilizing models of trauma and hemorrhagic shock. The findings from those experimental studies will also be correlated with data from surgical patients.

RESULTS

Recently, a gender-dimorphic immune and organ responsiveness in the susceptibility to and morbidity from shock, trauma, and sepsis has been found. Androgens have been shown to be responsible for the immunosuppression after trauma-hemorrhage in males. In contrast, female sex steroids exhibit immunoprotective properties after trauma and severe blood loss.

CONCLUSION

In view of these findings, clinically relevant therapeutic strategies have been developed using the testosterone receptor blocker flutamide and/or estrogen or agents with estrogenic effects, i.e., dehydroepiandrosterone, which might yield safe and useful therapeutic approaches for the treatment of immune depression in surgical patients.

Bacterial clearance and cytokine profiles in a murine model of postsurgical nosocomial pneumonia

The development of a nosocomial pneumonia is facilitated by alterations in host innate pulmonary antibacterial defenses following surgical trauma, which can result in decreased pulmonary bacterial clearance and increased morbidity and mortality. In a murine model of postoperative nosocomial infection, surgical stress (laparotomy) decreased Escherichia coli clearance from the lungs of animals that underwent surgery. Consistent with previous studies, (i) pulmonary levels of tumor necrosis factor alpha at 6 h and of interleukin-1beta (IL-1beta), IL-6, and gamma interferon (IFN-gamma) at 24 h post-bacterial infection (PBI) were decreased in animals that underwent laparotomy 24 h prior to E. coli infection (LAP/E. coli) compared to animals that received E. coli only; (ii) KC and macrophage inhibitory protein 2 were elevated at 6 h PBI in LAP/E. coli animals compared to E. coli-only animals; however, at 24 h PBI, levels were higher in the E. coli-only group; (iii) at 24 h PBI, monocyte chemoattractant protein 1 was lower in the LAP/E. coli group compared to the E. coli-only group; (iv) IL-10 levels were unaffected at all time points evaluated; and (v) the total number of neutrophils present in the lungs of LAP/E. coli animals at 6 h PBI was decreased in comparison to that in E. coli-only animals, resulting in decreased bacterial clearance and increased mortality in LAP/E. coli animals by 24 h PBI. Similar changes in cytokine profiles, pulmonary bacterial clearance, and mortality were consistent with reported findings in patients following surgical trauma. This model, therefore, provides a clinically relevant system in which the molecular and cellular mechanisms that lead to the development of nosocomial pneumonia can be further explored.

Are alterations of lymphocyte subpopulations in polymicrobial sepsis and DHEA treatment mediated by the tumour necrosis factor (TNF)-alpha receptor (TNF-RI)? A study in TNF-RI (TNF-RI(-/-)) knock-out rodents

Sepsis is associated with depression of T cell-dependent immune reactivity with proinflammatory cytokines, such as tumour necrosis factor (TNF)-alpha, playing an important role. Recent investigations describe an association between these immunological alterations and disturbances of the endocrine system, related most frequently to sex steroid hormones. Dehydroepiandrosterone (DHEA), one of the most abundant adrenal sex steroid precursors, seems to have a protective immunological effect towards septic insults. In this study, both the role of TNF-receptor I (RI) and possible interactions in the protective role of DHEA were investigated in a murine model of polymicrobial sepsis. Polymicrobial sepsis was induced by caecal ligation and puncture (CLP) in a murine model. The effects of DHEA on survival, clinical parameters and cellular immunity (T lymphocytes and natural killer (NK) cells) were investigated. CLP was performed in genetically modified TNF-RI knock-out (TNF-RI(-/-)) and genetically unmodified (wild-type, WT) mice. DHEA application was associated with a decrease in the mortality rate in WT animals. A mortality rate of 91.7% was observed in TNF-RI(-/-) mice after CLP. This mortality rate was reduced to 37.5% by the application of DHEA. In sham-operated TNF-RI(-/-) animals, a significantly higher proportion of NK cells within the lymphocyte population was measured compared with the corresponding WT group. After CLP, a significant increase in the percentage cell count of NK cells was recorded in WT mice. Overall, following DHEA application in WT mice, an alteration in the cellular immune response was characterized by a reduction in the percentage counts of CD4(+), CD8(+) and NK cells. In the group of TNF-RI(-/-) mice treated with DHEA, no increase in the percentage cell count of NK cells was observed after CLP. No data for cell analysis were available from the CLP-TNF-RI(-/-) mice treated with saline, due to the high mortality rate in these animals. DHEA reduces the complications of sepsis in a TNF-RI-independent manner. Our study suggests that NK cells are involved in the protective mechanism of DHEA in WT mice. It would therefore seem that DHEA represents a feasible alternative therapy for the dysregulated immune system in sepsis.

Clinical review: immunodepression in the surgical patient and increased susceptibility to infection

Several studies indicate that organ failure is the leading cause of death in surgical patients. An excessive inflammatory response followed by a dramatic paralysis of cell-mediated immunity following major surgery appears to be responsible for the increased susceptibility to subsequent sepsis. In view of this, most of the scientific and medical research has been directed towards measuring the progression and inter-relationship of mediators following major surgery. Furthermore, the effect of those mediators on cell-mediated immune responses has been studied. This article will focus on the effect of blood loss and surgical injury on cell-mediated immune responses in experimental studies utilizing models of trauma and hemorrhagic shock, which have defined effects on the immunoinflammatory response. Subsequently these findings will be correlated with data generated from surgical patients. The results of these studies may generate new approaches for the treatment of immunodepression following major surgery, thus reducing the susceptibility to infection and increasing the survival rate of the critical ill surgical patient.

Glutamine: essential for immune nutrition in the critically ill

Critically ill patients on intensive care units are at an increased risk of sepsis, which is a major cause of mortality in these patients. Recent evidence suggests that impairment of the functioning of the immune system contributes to the development of sepsis in such patients. In particular, monocytes show reduced expression of HLA-DR antigen, associated with impaired antigen presenting capability and decreased phagocytic activity; lymphocytes show decreased proliferation in response to mitogens and T-helper cells show a shift in the Th1/Th2 ratio consistent with impaired immunity. The amino acid glutamine becomes conditionally essential in the critically ill, yet such patients frequently have a marked deficiency of glutamine; the reasons for this are still unclear. Glutamine is required by the cells of the immune system both as a primary fuel and as a carbon and nitrogen donor for nucleotide precursor synthesis. In vivo studies have demonstrated that glutamine is essential for optimal immune cell functioning for monocytes, lymphocytes and neutrophils. A number of trials of patients fed by the enteral or parenteral route have shown improved infectious morbidity when supplemented with glutamine. However, the exact mechanism of glutamine action in these patients remains to be determined.

Changes in blood lymphocyte populations after multiple trauma: association with posttraumatic complications

OBJECTIVE

To study the frequency of several lymphocyte subsets, circulating cytokines, and prostaglandin plasma values at their time course over a period of 14 days in severely injured trauma patients in relation to the development of sepsis and multiple organ failure (MOF).

DESIGN

Prospective study.

SETTING

An operative intensive care unit (ICU) of a university hospital.

PATIENTS

Sixty-eight consecutive severely injured trauma patients.

INTERVENTIONS

Patients were separated into patients without sepsis and MOF (group 1, n = 51), and patients who developed sepsis and MOF (group 2, n = 17) during their stay in the ICU. Therapy was adjusted to the standards of modern intensive care management by physicians who were not involved in the study.

MEASUREMENTS AND MAIN RESULTS

In arterial blood samples, the profile of lymphocyte subset frequencies was performed by flow cytometry and, together with interleukin (IL)-1, IL-10, tumor necrosis factor (TNF)-alpha soluble TNF-alpha receptor 1 (sTNF-alpha r1 [p55]), and prostaglandin E2 (PGE2alpha)-alpha, serially measured after arrival in the ICU (baseline value) and during the next 14 days. Mean plasma IL-1 (29.3 +/- 5.8 [SD] pg/mL), TNF-alpha (138.5 +/- 22.4 pg/mL), and soluble TNF-alpha r1 (6.1 +/- 0.3 ng/mL) values were significantly higher in group 2 patients before clinical evidence of sepsis and MOF. With the onset of severe infections in group 2 patients, IL-1, TNF-alpha, and sTNF-alpha r1 values decreased, while immunosuppressive IL-10 (191.7 +/- 29.1 pg/mL) and PGE2alpha (87.7 +/- 20.4 pg/mL) values further increased and remained elevated during the time course. Analysis of lymphocyte subsets revealed a fall in total lymphocyte levels, in CD4+ T lymphocytes, and natural killer (NK) cells, but no change in CD8+ T lymphocyte subset. Despite a marked change in the T helper (CD4+) to T suppressor (CD8+) ratio (from 1:1.72 to 1:1.10), patients without MOF (group 1) had no significant difference in any of the markers tested compared with baseline values. In addition to the inverse CD4+/CD8+ T cell ratio (from 1:1.75 to 1:0.91) and increased activated T cells, each of these markers was significantly elevated and peaked before the onset of MOF in group 2 patients.

CONCLUSIONS

A severely depressed cellular immune response associated with increased suppressive mediators might be closely related to the development of severe sepsis and MOF in trauma patients. Therefore, an in-depth understanding of the deficits in host defense following multiple trauma will provide the basis for therapeutic interventions.

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.

Dehydroepiandrosterone sulphate in critical illness: effect of dopamine

OBJECTIVE

As part of a study on the effect of dopamine therapy on pituitary dependent hormone secretion in critical illness, we documented the impact of this inotropic and vasoactive catecholamine on the serum concentrations of dehydroepiandrosterone sulphate (DHEAS). Concomitantly, serum levels of PRL and cortisol were determined.

PATIENTS AND DESIGN

In a prospective, randomized, controlled, open-labelled clinical study, 20 critically ill, adult polytrauma patients receiving dopamine treatment (5 micrograms/kg/mi i.v. for a median 109 hours (range (21-296 hours)), were studied to evaluate the effect of dopamine withdrawal on serum concentrations of DHEAS, PRL and cortisol. The median age of the studied patients was 37 years (range 18-83 years).

MEASUREMENTS

Serum DHEAS and cortisol concentrations were measured by RIA and PRL by IRMA. The assessed serum samples were obtained at 0300 h on each of two consecutive study nights.

RESULTS

Withdrawal of dopamine infusion was found to elicit a median 25% increase of serum DHEAS concentrations within 24 hours whereas no significant change in DHEAS levels was observed when dopamine infusion was continued throughout both study nights (P = 0.01 continued vs interrupted dopamine). Prolactin levels were undetectable as long as dopamine was infused, and increased to a median of 317 IU/l after 24 hours of dopamine withdrawal (P = 0.0007). Elevated serum cortisol levels remained comparable with continued and interrupted dopamine infusion.

CONCLUSIONS

Dopamine infusion appears to suppress serum DHEAS concentrations in critically ill patients without affecting their elevated serum cortisol levels, suggesting a differential regulation of DHEAS and cortisol metabolism in critical illness. The lowering effect of dopamine on DHEAS levels could be linked to the concomitant suppression of circulating PRL. The simultaneous suppression of circulating PRL and DHEAS by dopamine infusion may be an iatrogenic factor maintaining or aggravating the anergic state of prolonged severe illness.

Association of transfusion with postoperative bacterial infection

Homologous blood transfusion has been implicated as a modulator of the host immune system in a number of clinical settings. Improved renal allograft survival is observed in patients receiving pretransplant transfusions. Decreased recurrence of active inflammatory bowel disease has been recently reported in transfused patients with Crohn's disease. Conversely, deleterious immunomodulatory effects of transfusion may explain the association between transfusion and increased susceptibility to cancer recurrence and bacterial and viral infection. Clinical studies regarding cancer recurrence and transfusion are retrospective and conflicting. There is epidemiologic evidence for more rapid progression of HIV-1 infection in heavily transfused patients. Studies on transfused surgical patients have shown transfusion to be associated with an increased frequency of postoperative bacterial infections. Some studies have come to different conclusions. These investigators have suggested that transfusion may represent a surrogate marker for other risk factors for infection. Animal models designed to control for confounding factors have supported an association between transfusion and bacterial infection severity in most, but not all, reports. Attempts to define the immunologic alterations associated with transfusion have revealed a generalized impairment of cellular immunity in both humans and animals. Although the preponderance of data supports an association between perioperative transfusion and increased susceptibility to postoperative bacterial infection, it is not certain to what extent this relationship constitutes cause and effect.

Spontaneous lymphocyte proliferation during trauma and infection

Spontaneous lymphocyte proliferation (SpP), measured in vitro as the rate of [14C]thymidine incorporation in blood lymphocytes, was investigated in non-infected postoperative patients, infected postoperative patients, and healthy volunteers, with 72, 24, and 3 h of lymphocyte culture. With 24-h cultures, infected postoperative patients showed 17-fold higher SpP than non-infected postoperative patients (2527 +/- 1552 versus 151 +/- 77 cpm, mean +/- SD, P less than 0.001) and 37-fold higher SpP than healthy volunteers (P less than 0.001). Postoperative patients without infection had twice as high SpP as healthy volunteers (P less than 0.001). Lymphocytes harvested after 24 h of cell culture showed significantly higher SpP than corresponding values at 72 and 3 h, in patients as well as in healthy volunteers (P less than 0.01). Infected postoperative patients showed a higher SpP than non-infected patients after only 3 h of cell culture (270 +/- 192 versus 48 +/- 10 cpm, P less than 0.001). An inverse correlation was observed between the level of SpP and body temperature in patients with postoperative infection (r = -0.62, P less than 0.05). The results indicate that lymphocytes are activated by uncomplicated surgery and particularly by postoperative infection, and that characteristics of SpP are reproducible in short cell-culture periods, which suggests that in vitro measurements of SpP may be of value in the detection of severe postoperative infection.

Complications from i.v. therapy: results from field-started and emergency department-started i.v.'s compared

Because the complications resulting from IV therapy started outside the hospital seem inordinately higher than those resulting from IV therapy started in the emergency department, we undertook a comparative two-month study of the complications resulting from both sources. We found the number and severity of complications from IV therapy started in the field significantly greater than complications from that started in the ED. The phlebitis rate in the prehospital group was 4.65 times that in the ED group (P less than .001). The percentage of patients with unexplained fever in the prehospital group was 5.58 times that in the ED group (P less than .01). Means for reducing the complications and areas for further research are suggested.

Influence of surgical stress on cellular immunity and the induction of plastic adherent suppressor cells of spleen in mice

Surgical stress animal models were established by performing laparotomies on mice. It was found that this type of stress could suppress the natural killer (NK) cytotoxicity and the proliferation of spleen cells induced by conA or lipopolysaccharide (LPS). Dynamic changes showed that the stress-mediated immunosuppression was reversible, as the responses to conA and LPS would be restored with time. The sensitivity to the stress-mediated suppression was different according to variations in immunological parameters. Furthermore, the macrophages in spleen were tested by isolation by the plastic-adherent procedure. The results showed clearly that these adherent cells (Plastic Adherent Cells, PAC) possessed an immunosuppressive effect on mitogen-induced lymphocyte proliferation in post-operative mice, but not in normal mice. Treatment of mice with indomethacin blocked the PAC-mediated immunosuppression. Surgical stress appeared to increase the level of prostaglandins, which in turn induced the production of suppressor PAC.

Defective T-cell differentiation in acquired immune deficiency syndrome (AIDS)

A decline in T-cell lymphocyte number is the central characteristic of acquired immune deficiency syndrome (AIDS). The reason for the loss of these cells is not well understood. We investigated the hypothesis that defects in T-cell differentiation contributed to T-cell loss using an in vitro colony assay that measures T-cell precursor (CFU-T) frequency. The results indicate a substantial generalized decrease in CFU-T in people with AIDS (P less than 0.01), most of whom have Kaposi's sarcoma, and an occasionally severe decrease in CFU-T in people with ARC. Some of the cells from low colony formers suppressed colony formation by control cells. In addition, plasma from people with AIDS was less supportive of colony growth than control plasma. Decreased Ia expression on adherent mononuclear cells did not correlate with colony formation. A defect in T-cell repopulation can help explain the loss of T cells associated with AIDS.