Changes in T lymphocyte subsets following injury. Assessment by flow cytometry and relationship to sepsis

Pathophysiological dynamics in the contact, coagulation, and complement systems during sepsis: Potential targets for nafamostat mesilate

Sepsis is a life-threatening syndrome resulting from a dysregulated host response to infection. It is the primary cause of death in the intensive care unit, posing a substantial challenge to human health and medical resource allocation. The pathogenesis and pathophysiology of sepsis are complex. During its onset, pro-inflammatory and anti-inflammatory mechanisms engage in intricate interactions, possibly leading to hyperinflammation, immunosuppression, and long-term immune disease. Of all critical outcomes, hyperinflammation is the main cause of early death among patients with sepsis. Therefore, early suppression of hyperinflammation may improve the prognosis of these patients. Nafamostat mesilate is a serine protease inhibitor, which can inhibit the activation of the complement system, coagulation system, and contact system. In this review, we discuss the pathophysiological changes occurring in these systems during sepsis, and describe the possible targets of the serine protease inhibitor nafamostat mesilate in the treatment of this condition.

The Burn Wound Microenvironment

Significance: While the survival rate of the severely burned patient has improved significantly, relatively little progress has been made in treatment or prevention of burn-induced long-term sequelae, such as contraction and fibrosis. Recent Advances: Our knowledge of the molecular pathways involved in burn wounds has increased dramatically, and technological advances now allow large-scale genomic studies, providing a global view of wound healing processes. Critical Issues: Translating findings from a large number of in vitro and preclinical animal studies into clinical practice represents a gap in our understanding, and the failures of a number of clinical trials suggest that targeting single pathways or cytokines may not be the best approach. Significant opportunities for improvement exist. Future Directions: Study of the underlying molecular influences of burn wound healing progression will undoubtedly continue as an active research focus. Increasing our knowledge of these processes will identify additional therapeutic targets, supporting informed clinical studies that translate into clinical relevance and practice.

Low CD8 T cells in neonates and infants prior to surgery, and health-care-associated infections: prospective observational study

BACKGROUND

Major surgery suppresses the cell-mediated immune response in children and adults. Data on preoperative and postoperative T-cell counts in pediatric surgical patients and their relationship to health-care-associated infection (HAI) are not yet known.

METHODS

A prospective observational study was carried out in a level III multidisciplinary neonatal and pediatric intensive care unit. Before and after, and in the first 3 days after surgery, lymphocyte subsets in peripheral blood were measured in 28 neonates and infants on flow cytometry. HAI were classified according to CDC/NHSN criteria.

RESULTS

Six out of 28 neonates and infants (21.4%) developed HAI (group I-HAI), while 22 out of 28 (78.6%) remained infection free (group II-non-HAI). In group I with HAI, the preoperative median cytotoxic T-lymphocyte (CD8-T-cell) level was found to be below normal, and remained very low throughout the study period. In addition, the median and interquartile CD8 T-cell range (358 cells/μL; 304-424 cells/μL) were twice as low compared to group II without HAI (822 cells/μL; 522-933 cells/μL; P = 0.013). No differences were found between the two groups with regard to patient demographics and clinical data.

CONCLUSION

Neonates and infants who underwent a major surgical procedure and who had a very low preoperative CD8 T-cell level, developed HAI postoperatively.

Gram-negative bacterial infection in thigh abscess can migrate to distant burn depending on burn depth

Sepsis remains the major cause of death in patients with major burn injuries. In the present investigation we evaluated the interaction between burn injuries of varying severity and preexisting distant infection. We used Gram-negative bacteria (Pseudomonas aeruginosa and Proteus mirabilis) that were genetically engineered to be bioluminescent, which allowed for noninvasive, sequential optical imaging of the extent and severity of the infection. The bioluminescent bacteria migrated from subcutaneous abscesses in the leg to distant burn wounds on the back depending on the severity of the burn injury, and this migration led to increased mortality of the mice. Treatment with ciprofloxacin, injected either in the leg with the bacterial infection or into the burn eschar, prevented this colonization of the wound and decreased mortality. The present data suggest that burn wounds can readily become colonized by infections distant from the wound itself.

Use of the relationship between absolute lymphocyte count and CD4 count to improve earlier consideration of pneumocystis pneumonia in HIV-positive emergency department patients with pneumonia

BACKGROUND

The ability to accurately assess the level of immunosuppression in HIV+ patients in the emergency department (ED) is often limited and can affect management of these patients.

OBJECTIVE

To evaluate the relationship between the absolute lymphocyte count (ALC) and CD4 count in HIV patients admitted through the ED with pneumonia and how utilization of this relationship may affect early consideration and evaluation of Pneumocystis jiroveci pneumonia (PCP).

METHODS

Retrospective multicenter 5-year study of HIV+ patients with an ICD-9 diagnosis of pneumonia. Included patients had an ALC measured on ED presentation and a CD4 count measured in < 24 h. A receiver operator curve (ROC), decision plot analysis, and McNemar test of proportions were used to characterize the relationship between study variables.

RESULTS

Six hundred eighty six patients were enrolled, 23.2% (95% confidence interval [CI] 20.2-26.1) were diagnosed with PCP. The geometric mean CD4 count and ALC were 81 and 1089, respectively. The correlation between ALC and CD4 was r = 0.60 (95% CI 0.55-65, p < 0.01). The ROC was 0.78 (0.75-0.82). An ALC < 1700 cells/mm(3) had a sensitivity of 84% (95% CI 80-87) and specificity of 55% (95% CI 48-70) for a CD4 < 200 cells/mm(3). An ALC threshold of 1700 cells/mm(3) would have identified 86% of patients with PCP but falsely identified 2.5 patients without PCP for every one accurately identified.

CONCLUSION

The ALC threshold of 1700 cells/mm(3) retains significant discriminatory value and would moderately improve identification of patients with a CD4 < 200 cells/mm(3) but is not likely to be reliable as the sole method of early recognition and evaluation of PCP.

Perioperative period: immunological modifications

Surgical stress induces complex modifications in the hemodynamic, metabolic, neuro-hormonal and immune response of the individual. The magnitude of these alterations depends on preoperative events leading to surgery, the severity of surgical trauma, and also on post-operative/post-traumatic complications (multiple hit hypothesis). As in other conditions of tissue damage, surgery trauma is followed by an immune-inflammatory response, initiated at the site of injury by the innate immune system, followed by a compensatory anti-inflammatory (or immunosuppressive) response (CARS), involving mainly cells of the adaptive immune system, which predispose the host to septic complications. The up-regulated inflammatory response, together with a profound impairment of macrophage and cell-mediated immunity, appear to be the cause for patients&#x0027; increased susceptibility in developing subsequent sepsis after major surgery.

The compensatory anti-inflammatory response syndrome (CARS) in critically ill patients

Like the systemic inflammatory response syndrome (SIRS), the compensatory anti-inflammatory response syndrome (CARS) is a complex pattern of immunologic responses to severe infection or injury. The difference is that while SIRS is a proinflammatory response tasked with killing infectious organisms through activation of the immune system, CARS is a global deactivation of the immune system tasked with restoring homeostasis. Much research now suggests that the timing and relative magnitude of this response have a profound impact on patient outcomes.

Acute alcohol intoxication potentiates neutrophil-mediated intestinal tissue damage after burn injury

This study examined whether acute alcohol (EtOH) intoxication before burn injury potentiates postburn intestinal tissue damage and whether neutrophils have any role in the damage under those conditions. Male rats ( approximately 250 g) were gavaged with EtOH to achieve a blood EtOH level of approximately 100 mg/dL or with saline and received either approximately 12.5% or approximately 25% total body surface area (TBSA) burn or sham injury. Rats were killed at 4 or 24 h after injury, and various parameters were measured. As compared with sham animals, burn injury alone (regardless of size) resulted in a significant increase in intestinal tissue myeloperoxidase (MPO; an index of neutrophil infiltration) activity and IL-18 levels 4 h after injury. Furthermore, rats receiving 25% TBSA, but not 12.5%, burn exhibited intestine edema. The IL-18 and MPO activity were normalized at 24 h after injury in rats receiving 12.5% TBSA burn, whereas these parameters remained elevated at 24 h in rats with 25% burn. The presence of EtOH in rats at the time of burn injury exacerbated the levels of IL-18, MPO activity, and edema at 4 and 24 h after burn injury. Treatment of rats with anti-IL-18 antibodies or with antineutrophil antiserum prevented the increase in the above parameters after EtOH and burn injury, except that the depletion of neutrophils did not prevent the IL-18 increase. In summary, these findings suggest that acute EtOH intoxication exacerbates postburn intestinal tissue damage after burn injury, and that it is, in part, neutrophil mediated.

Cytomegalovirus and burns: current perceptions, awareness, diagnosis, and management strategies in the United States and Germany

Trauma and immunosuppressed patients are at risk for cytomegalovirus (CMV) disease. Attributing pathogenicity in burn patients remains difficult and controversial because data are sparse. In this work, we surveyed U.S. and German burn centers and evaluated them for awareness, perceptions, diagnosis, and treatment of CMV in patients with burn injury. A total of 58% German (G) and 21% U.S. centers responded. CMV infection incidence was 1:280 G and 1:870 U.S. A total of 41% G and 78% U.S. burn centers considered CMV to be of minor importance and 41% G and 13% U.S. centers considered CMV to be of significant importance. A total of 70% G and 97% U.S. centers performed no admission screening. When testing, 70% G and 19% U.S. centers used serology; 52% G and 25% U.S. centers used body fluid viral isolation; and 43% G and 6% U.S. centers used leukocyte CMV-DNA analysis. A total of 72% G and 48% U.S. centers distinguished infection from disease. Human CMV disease was diagnosed by CMV-DNA (82% G, 19% U.S.), direct virus isolation (43% G, 13% U.S.), or RNA detection (26% G, 0% U.S.). A total of 43% G and 19% U.S. would treat the established disease. Establishing consistent guidelines for screening, diagnosis, and treatment seems prudent in caring for the immunocompromised burn patient.

Burn wound infections

Burns are one of the most common and devastating forms of trauma. Patients with serious thermal injury require immediate specialized care in order to minimize morbidity and mortality. Significant thermal injuries induce a state of immunosuppression that predisposes burn patients to infectious complications. A current summary of the classifications of burn wound infections, including their diagnosis, treatment, and prevention, is given. Early excision of the eschar has substantially decreased the incidence of invasive burn wound infection and secondary sepsis, but most deaths in severely burn-injured patients are still due to burn wound sepsis or complications due to inhalation injury. Burn patients are also at risk for developing sepsis secondary to pneumonia, catheter-related infections, and suppurative thrombophlebitis. The introduction of silver-impregnated devices (e.g., central lines and Foley urinary catheters) may reduce the incidence of nosocomial infections due to prolonged placement of these devices. Improved outcomes for severely burned patients have been attributed to medical advances in fluid resuscitation, nutritional support, pulmonary and burn wound care, and infection control practices.

Cytomegalovirus infection in burns: a review

Sepsis is responsible for significant morbidity and mortality in patients suffering from severe burn injuries. Burn patients are known to be immunocompromised, and it is generally accepted that the immunosuppressed patient may experience human cytomegalovirus (HCMV) infection and disease. Review of the very limited available literature identifies a seroconversion rate of between 18 and 22% for burn patients who were seronegative for HCMV prior to suffering their burn injury. Furthermore, approximately 50% of HCMV antibody-positive patients may reactivate. Blood products and allografted skin have clinically been identified as possible sources of HCMV transmission in burn patients. Experience in the treatment of infection or disease in burn patients is very scarce and limited to immunoglobulin therapy. Animal experiments have demonstrated that murine cytomegalovirus (MCMV)-seropositive skin grafts are able to infect immunodeficient mice as well as burned mice. Murine studies have also demonstrated that infection with MCMV enhances susceptibility to secondary bacterial infection and increases mortality in these animals. Burned mice challenged with MCMV have a significantly higher level of bacterial translocation to mesenteric lymph nodes than either control thermally injured mice without MCMV inoculation or non-burned mice injected with MCMV alone. In summary, it remains controversial whether HCMV infection per se alters outcome for the majority of burn patients. Subgroups of severely burned, seronegative patients may benefit from blood products and skin from seronegative donors. Antiviral strategies are not yet evaluated for the burn patient. Further investigations utilizing modern diagnostic techniques seem necessary.

Burn wound infections

Burns are one of the most common and devastating forms of trauma. Patients with serious thermal injury require immediate specialized care in order to minimize morbidity and mortality. Significant thermal injuries induce a state of immunosuppression that predisposes burn patients to infectious complications. A current summary of the classifications of burn wound infections, including their diagnosis, treatment, and prevention, is given. Early excision of the eschar has substantially decreased the incidence of invasive burn wound infection and secondary sepsis, but most deaths in severely burn-injured patients are still due to burn wound sepsis or complications due to inhalation injury. Burn patients are also at risk for developing sepsis secondary to pneumonia, catheter-related infections, and suppurative thrombophlebitis. The introduction of silver-impregnated devices (e.g., central lines and Foley urinary catheters) may reduce the incidence of nosocomial infections due to prolonged placement of these devices. Improved outcomes for severely burned patients have been attributed to medical advances in fluid resuscitation, nutritional support, pulmonary and burn wound care, and infection control practices.

Interleukin-16 expression in the peripheral blood and CD8 T lymphocytes after traumatic injury

BACKGROUND

Expressed in several pathologic conditions, interleukin (IL-16) can induce chemotaxis and regulate the activation of CD4-positive leukocytes. This study investigated the expression of IL-16 in trauma patient plasma and peripheral blood leukocytes to determine its involvement in the physiologic response to injury.

METHODS

In this study, 25 consecutive patients requiring trauma team activation and 15 noninjured subjects were evaluated for plasma IL-16 by enzyme-linked immunosorbent assay and peripheral blood leukocyte expression of intracellular cytokine by flow cytometry.

RESULTS

Trauma patient plasma IL-16 was transiently increased after injury in comparison with levels in noninjured control subjects. In patients with worse outcome, both peripheral blood T lymphocyte intracellular IL-16 levels and CD4/CD8 lymphocyte ratios were lower than those for less severely injured patients and control subjects.

CONCLUSION

Posttraumatic changes in IL-16 expression were found to be associated with worse patient outcome, suggesting an innate immune mechanism with a role in regulation of the T lymphocyte response to injury.

Relationships between burn size, immunosuppression, and macrophage hyperactivity in a murine model of thermal injury

Burn injury induces immune dysfunction and alters numerous physiological parameters. While clinical studies indicate that burn injury size profoundly impacts patient immune status, only limited experimental studies have systematically addressed its impact on immune functional parameters. In the present study, mice were subjected to burn injuries of varying sizes and splenic immune cells (splenocytes and macrophages) were isolated 7 days thereafter. Burn injury suppressed splenic T-cell proliferation in an injury size-dependent manner that correlated with the release of the immunosuppressive mediators PGE(2) and nitric oxide. In addition, a shift towards an immunosuppressive Th-2 cytokine profile and a hyperactive macrophage phenotype (increased release of inflammatory mediators) was observed post-injury, however, this effect was in part independent of burn size. Thus, unlike patient survival data, burn injury-induced changes in immune function do not necessarily correlate with the size of the injury.

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.

Infection control: avoiding the inevitable

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

Cellular immunity after ethanol exposure and burn injury: dose and time dependence

Acute ethanol exposure prior to burn injury increases the immune dysfunction seen with burn alone, which has been partially attributed to increased circulating and splenic macrophage production of interleukin-6 (IL-6). The current studies examined the effect dose and timing of ethanol exposure prior to burn on cellular immunity. Mice with high (300 mg/dl) circulating levels of ethanol at the time of burn demonstrated further suppression of the delayed type hypersensitivity (DTH) and splenocyte proliferative responses in comparison to mice with moderate (100 mg/dl) ethanol levels. Interestingly, the increase in macrophage IL-6 secretion seen at the moderate dose was not augmented at the high dose; however, the circulating IL-6 levels did reveal a further increase at the high ethanol dose. There were no alterations in splenocyte subset populations and/or apoptosis at the moderate vs. the high ethanol dose. Moderate ethanol exposure 24 h, in comparison to 30 min, before injury resulted in similar decreases in the DTH. These results suggest that the dose-dependent effects of ethanol on immunity following burn injury are not the result of splenic macrophage IL-6 production as shown at the moderate dose and that the immune suppressive effects of ethanol in this model persist after it is cleared from the circulation.

Leucocyte activation markers in clinical practice

The response against tissue injury and infection begins with the early activation of molecular and cellular elements of the inflammatory and immune response. Severe tissue injury, necrosis, and infection induce imbalanced inflammation associated with leukocyte over-stimulation and excessive or dysregulated release of cellular mediators. Clinical and experimental studies have shown that these mediators are directly related to progressive post-injury complications. Persistent increased levels of pro-inflammatory mediators produce tissue injury. Excessive production and activity of anti-inflammatory mediators cause anergy and/or immune dysfunction with increased susceptibility to infection. Leukocyte activation is assessed by cell surface phenotype expression, cellular mediators determination, or by measuring functional responses using isolated cells. Potential routine clinical uses are: evaluation of severity and prognosis in critically ill patients, immunomonitoring of sepsis, and detection of tissue injury, necrosis, and infection. In practice, the determination of cellular activation markers is restricted by a limited number of automated methods and by the cost of reagents. The availability of flow cytometry and immunoassay automated systems can contribute to a wider use in practice. Here we review the immunopathophysiology of polymorphonuclear neutrophil, monocyte, macrophage, and lymphocyte activation in response to tissue injury and infection. In addition, laboratory methods for their determination, and clinical applications in practice, are discussed.

HLA-DR expression and soluble HLA-DR levels in septic patients after trauma

OBJECTIVE

To determine if cellular and soluble HLA-DR molecules may be relevant in severely injured patients for the development of gram-positive or gram-negative sepsis.

SUMMARY BACKGROUND DATA

HLA-DR molecules play a central role in the specific immune response to infection. The reduced HLA-DR expression on monocytes is considered to correlate with infectious complications and the development of sepsis. Data on the role of HLA-DR expression on T cells and soluble HLA-DR molecules are rare.

METHODS

HLA-DR expression on monocytes and T cells was measured by flow cytometry. Plasma levels of soluble HLA-DR were studied by enzyme-linked immunosorbent assay.

RESULTS

HLA-DR expression on circulating T cells, calculated as mean fluorescence intensity in channels, was reduced at day 1 after admission in 20 patients with subsequent severe sepsis compared with 46 patients without sepsis. The septic patients immediately after trauma had significantly lower soluble HLA-DR plasma levels than the nonseptic patients. At day 2 after admission, HLA-DR expression on monocytes was significantly lower in the severe sepsis group than in the patients without sepsis, and lasted until day 14 after injury.

CONCLUSIONS

In severely injured patients, decreased levels of cellular and soluble HLA-DR appear as early indicators of an immune deviation associated with the development of severe sepsis. Moreover, immune alterations of different cell types may promote distinct kinds of septicemia.

Laparoscopic-assisted vs. open surgery for colorectal cancer: comparative study of immune effects

PURPOSE

Our aim was to test the hypothesis that laparoscopic-assisted resection for colorectal cancer has an immunologic advantage over traditional open surgery.

METHODS

Sixteen patients with colorectal cancer were randomized to undergo laparoscopic-assisted resection or open surgery. Basic patient data were recorded, and serum interleukin-6 levels, relative proportions of lymphocytes, and human leukocyte antigen-DR expression on monocytes were determined at specific time intervals.

RESULTS

Operating time was longer for laparoscopic-assisted resection (P=0.02), but analgesic requirements were less (P=0.04). All patients exhibited the following: interleukin-6 levels increased to a maximum at 4 hours and returned to preoperative levels within 48 hours. This response appeared greater for open resection (mean peak level, 313 vs. 173 pg/ml; P=0.25). Relative granulocytosis (P < 0.001) was seen within 48 hours, which was offset by a decrease in percentage of lymphocytes (P < 0.001). Changes in lymphocyte subfractions were most significant seven days postsurgery: natural killer cells decreased (P=0.003); T cells increased (P=0.008), with elevation in the CD4/CD8 ratio (P=0.003). B cells were largely unchanged at all time periods. Human leukocyte antigen-DR expression on monocytes was significantly less at 48 hours postsurgery (P < 0.001). All changes were reversed within three weeks of surgery. There were no differences when comparing laparoscopic-assisted resection with open surgery.

CONCLUSIONS

Both laparoscopic-assisted resection and open surgery affect the immune response. It would appear that laparoscopic-assisted resection does not have an immunologic advantage over open surgery in patients with colorectal cancer.

Lymphocyte function in wound healing and following injury

BACKGROUND

Injury activates a cascade of local and systemic immune responses.

METHODS

A literature review was undertaken of lymphocyte function in wound healing and following injury.

RESULTS

Lymphocytes are not required for the initiation of wound healing, but an intact cellular immune response is essential for a normal outcome of tissue repair. Injury affects lymphocyte immune mechanisms leading to generalized immunosuppression which, in turn, increases host susceptibility to infection and sepsis. Although the exact origin of post-traumatic immunosuppression remains unknown, stress hormones and immunosuppressive factors, such as inflammatory cytokines, prostaglandin E2 and nitric oxide, affect lymphocyte function adversely. Post-traumatic impairment of T lymphocyte immune function is reflected in decreased lymphocyte numbers, as well as altered T cell phenotype and activity. Antibody-producing B lymphocytes are variably affected by injury, probably secondary to alterations of T lymphocyte function, as a result of their close interaction with helper T cells. Therapeutic modulation of the host immune response may include non-specific and specific interventions to improve overall defence mechanisms.

CONCLUSION

Early resuscitation to restore lymphocyte function after injury is important for tissue repair and the prevention of immunosuppression.

The influence of laparoscopy on lymphocyte subpopulations in the surgical patient

BACKGROUND

Surgical stress is known to disturb the immune system so that the overall picture is one of generalized immunosuppression proportional to the degree of stress. It has been suggested that minimally invasive procedures, i.e., laparoscopic cholecystectomy, should be accompanied by decreased surgical stress.

METHODS

The present study utilized a panel of monoclonal antibodies to identify peripheral blood lymphocyte subpopulations in 11 patients scheduled for elective laparoscopic cholecystectomy. These were obtained immediately preoperatively, one day postoperatively, and one week postoperatively.

RESULTS

The results demonstrated a significant (p < 0.05) decrease in T-helper to T-suppressor cell ratios the first day postoperatively compared to the preoperative ratios; the mean decrease was 13% below the preoperative ratios. There was no significant change in the ratios one week postoperatively.

CONCLUSIONS

Even though laparoscopic cholecystectomy has been documented to have less disability and postoperative pain than open cholecystectomy, alterations in immune function, although attenuated, do persist.

T-lymphocyte subsets in acute illness

OBJECTIVES

To determine the range of T-lymphocyte subsets (CD4, CD8, and CD4/CD8 ratios) in acutely ill, hospitalized patients and to determine whether these concentrations correlate with illness severity, survival rate, or immunodepression.

DESIGN

Cross-sectional study, comparing Acute Physiology and Chronic Health Evaluation II (APACHE II) scores and the calculated, disease-specific, predicted mortality rate with T-lymphocyte subsets.

SETTING

Urban county hospital intensive care unit (ICU), serving as the designated trauma center.

PATIENTS

One hundred two consecutively admitted ICU patients (72 medical and 30 surgical).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patient clinical data, APACHE II scores, and their associated predicted mortality rate were recorded. Blinded human immunodeficiency virus (HIV) and lymphocyte testing was performed on samples from all patients on ICU admission. Despite only three (2.9%) of 102 patients testing positive for HIV antibodies, 41% (42/102) of patients had CD4 concentrations of < 400 cells/microL, and 29% (29/102) had CD4 concentrations of < 300 cells/microL. Mean CD8 concentrations were even lower, compared with normal laboratory values, resulting in a slight increase in CD4/CD8 ratios, although 16% (16/102) of patients had a CD4/CD8 ratio of < 1. CD4 counts were linearly related to total lymphocyte concentrations (Pearson correlation coefficient = 0.948), but no relationship was found between total lymphocyte or lymphocyte subset counts and APACHE II score, predicted mortality rate, or survival rate.

CONCLUSIONS

Acute illness alone, in the absence of HIV infection, can be associated with profound decreases of T-lymphocyte populations. This problem is unpredictable and does not correlate with severity of illness, predicted mortality rate, or actual mortality rate. No conclusions regarding HIV serostatus or survival can be made based on single measurements of T-cell concentrations in acutely ill hospitalized patients.

Altered leukocyte immunophenotypes in septic shock. Studies of HLA-DR, CD11b, CD14, and IL-2R expression

To evaluate the role of cellular activation markers and functional surface molecules in sepsis, specific immunophenotypes on peripheral blood leukocytes were studied in 40 subjects consisting of the following: (1) patients with septic shock; (2) patients with sepsis; (3) critically ill nonseptic patients; and (4) normal control subjects. These assays included phagocyte adhesion molecule CD11b expression, monocyte receptors HLA-DR and CD14, and lymphocyte activation markers IL-2R and HLA-DR. Patients with septic shock and sepsis had significantly increased neutrophil CD11b expression compared with normal subjects. Neutrophil HLA-DR expression did not significantly differ between groups. Monocytes from septic shock patients had significantly less HLA-DR expression than normal subjects and there was a trend toward a lower proportion of gated monocytes that expressed CD14 in septic shock patients. Septic shock patients had no significant increases in IL-2R or HLA-DR expression on CD3 lymphocytes compared with control subjects, but they had significantly lower numbers of total, CD3, CD4, and CD8 lymphocytes and a higher prevalence of anergy. Septic shock patients manifested an increase in neutrophil CD11b expression that may play a role in organ injury. In contrast, a more specific decrease in monocyte expression of functional antigens is also observed in patients with septic shock that may have implications for immunologic defense mechanisms.

Temporal analysis of human leucocyte surface antigen expression and neutrophil respiratory burst activity after thermal injury

Sepsis, the major cause of morbidity and mortality after burn injury, is related to multiple immune derangements. Using monoclonal antibodies and two-colour flow cytometry to identify surface antigens, peripheral blood mononuclear cell (PBMC) populations were analysed and correlated with lymphocyte proliferation assays for 21 days postinjury. In addition, in vitro expression of activation antigens by mitogen-stimulated PBMCs was analysed during the time period. Twenty-nine burn patients were studied, with burn injuries ranging from 19 to 97 per cent TBSA; PBMCs from human volunteers were used for control cells. Patients received aggressive enteral nutritional support starting day 1 postburn and underwent early excision and grafting of wounds; no patients developed sepsis during the study period. The most consistent changes in PBMCs after thermal injury were decreased percentages of total T cells (CD3+), T helper/inducer cells (CD4+), and T suppressor/cytotoxic cells (CD8+); the percentages of natural killer (CD16+) cells were not altered. Expression of surface 'activation' antigens on CD4+ and CD8+ cells (HLA-DR, interleukin-2 receptor and transferrin receptor) after mitogen stimulation was significantly depressed as early as 1 day postburn. An early monocytosis was seen on day 1 postburn, but decreases were found on days 4 and 7. Monocyte expression of HLA-DR antigen was suppressed throughout the study. Lymphocyte proliferation after mitogen stimulation and the responses of lymphocytes in mixed lymphocyte culture were suppressed postburn. Neutrophil respiratory burst responses were supranormal on days 1 and 7 postburn, but the differences were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucocorticoid receptors in mononuclear cells of patients with sepsis

Glucocorticoid receptor (GR) hormone-binding activity was studied by a whole-cell method in mononuclear cells (MNC) from peripheral blood of 7 patients during the hemodynamic compensatory phase of sepsis. 4 patients were receiving dopamine, which did not affect the GR count. The patients' plasma cortisol concentrations were normal or slightly elevated. Despite a wide range, the mean GR count and affinity in MNC from septic patients did not differ from those in normal controls, suggesting that glucocorticoids could still be effective in the hemodynamic compensatory phase of sepsis.

Risk factors for infection in the trauma patient

The most common cause of late death following trauma is sepsis. The traumatized patient has a significant increased risk of infection. Transfusion, hypotension, and prolonged ventilatory support are predictive of septic complications. In addition, the trauma patient has a higher predisposition to pneumonia than nontrauma patients (18% versus 3% incidence of pneumonia, P < .001). Additional risk factors include the degree of nutrition status and the type of medications used during surgery. Immunologic depression may be an additional risk factor. There is mounting evidence that trauma can result in host defense abnormalities. To prevent the significant mortality caused by sepsis, close surveillance must be maintained, nutritional status must be optimal, and liberal use of antibiotics should be discouraged. Their use should be guided by appropriate cultures and sensitivities.

Reversibility of alcohol-induced immune depression

Alcohol abusers have suppressed cellular immune function. The aim of the study was to investigate the time of sobriety required to normalize immune function. Delayed hypersensitivity was investigated during disulfiram controlled abstinence in ten heavy alcoholics and in seven moderate drinkers without liver diseases. For comparison a control group of eight previous drinkers was tested. The skin test responses were modest initially with a median area of response of 12 mm2 (range 0-31) in the heavy alcoholics and 3 mm2 (0-15) in the moderate drinkers. It improved significantly in both groups after two weeks of sobriety. The responses stabilized after 8 weeks at 74 mm2 (54-102) in the heavy alcoholics and after 9 weeks at 63 mm2 (42-76) in the moderate drinking group. The control group had skin test responses of 70 mm2 (46-87), not different from the responses of the alcohol groups after two months of abstinence. The results suggest that while 2 weeks of abstinence from alcohol will improve the depressed cellular immunity, 2 months of sobriety is necessary to normalize it.

Impairment of helper T-cell function following severe head injury

Major infections, such as sepsis and pneumonia, occur in 50-75% of patients following isolated severe head injury. Previous studies have demonstrated that this high incidence of infection following severe head injury may be related to a decrease in helper T-cell activation and function. The present study was designed to investigate the effect of severe head injury on specific subgroups of helper T cells known to enhance or suppress cellular immune function. Specifically, peripheral blood lymphocytes (PBLs) from 10 head-injured patients and 10 matched controls were evaluated following in vitro stimulation with the T-cell mitogen, phytohemagglutinin (PHA). Subsets of helper T cells evaluated included activated helper (CD4+/CD25+) T cells; helper/inducer (CD4+/CDw29+) T cells, which enhance cellular immune activity; and suppressor/inducer (CD4+/CD45R+) T-cells, which induce suppressor (CD8+) T-cells. In addition, the effect of intraventricular fluid (IVF) on PHA-stimulated in vitro CD4 and CD25 expression was investigated to determine whether severe head injury results in the production of mediators within the central nervous system capable of affecting T-cell activation. The results of this study indicate that isolated severe head injury selectively reduces the ability of PHA-stimulated PBLs to express the helper/inducer (CD4+/CDw29+) T-cell (p = 0.023) and activated helper (CD4+/CD25+) T-cell (P = 0.041) phenotypes. There was no significant change in PHA-stimulated CD4 or CD25 expression following incubation of PBLs with intraventricular fluid (IVF) from head-injured patients. The relationship between these changes in specific helper T-cell subpopulations and the infectious complications of severe head injury are discussed.

Impairment of helper T-cell function and lymphokine-activated killer cytotoxicity following severe head injury

Infection is a major complication of severe head injury, occurring in 50% to 75% of patients who survive to hospitalization. Previous investigations of immune activity following head injury have demonstrated suppression of helper T-cell activation. In this study, the in vitro production of interferon-gamma (INF-gamma), interleukin-1 (IL-1), and interleukin-2 (IL-2) was determined in 25 head-injured patients following incubation of peripheral blood lymphocytes (PBL's) with the lymphocyte mitogen phytohemagglutin (PHA). In order to elucidate the functional status of cellular cytotoxicity, lymphokine-activated killer (LAK) cell cytotoxicity assays were performed both prior to and following incubation of PBL's with IL-2 in five patients with severe head injury. The production of INF-gamma and IL-2 by PHA-stimulated PBL's was maximally depressed within 24 hours of injury (p less than 0.001 for INF-gamma, p = 0.035 for IL-2) and partially normalized within 21 days of injury. There was no change in the production of IL-1. When comparing the in vitro LAK cell cytotoxicity of PBL's from head-injured patients and normal subjects, there was a significant depression in LAK cell cytotoxicity both prior to (p = 0.010) and following (p less than 0.001) incubation of PBL's with IL-2. The results of this study indicate that IL-2 and INF-gamma production, normally required for inducing cell-mediated immunity, is suppressed following severe head injury. The failure of IL-2 to enhance LAK cell cytotoxicity suggest that factors other than decreased IL-2 production, such as inhibitory soluble mediators or suppressor lymphocytes, may be responsible for the reduction in cellular immune activity following severe head injury. These findings may have significant implications in designing clinical studies aimed at reducing the incidence of infection following severe head injury.

Suppression of cellular immune activity following severe head injury

Infection is a major cause of morbidity following multiple traumatic and head injury. Although immunosuppression has been demonstrated after multiple traumatic injury, the effects of head injury on immune function have not been thoroughly investigated. In a prospective study of 10 severely head-injured patients, in vitro and in vivo parameters of cellular immune activity were assessed. In vitro measurements of lymphocyte surface antigen expression following mitogen stimulation were made serially over a 3-week period in 10 patients with severe head injury. The control group consisted of 20 healthy subjects. Phenotyping of peripheral blood lymphocytes (PBLs) was performed following incubation with and without mitogens. Phenotypes were determined by flow cytometry using monoclonal antibodies (MABs) to T lymphocyte subsets and the alpha subunit of interleukin 2 (IL-2) receptors. In vivo cellular immune function was determined by measuring patient responses to delayed-type hypersensitivity (DTH) skin testing within 24 h of injury. When head-injured patients were compared to controls, PBLs incubated in the presence of phytohemagglutinin (PHA) demonstrated a decrease in cells marking as T cells (p = 0.005), helper-inducer T cells (p = 0.001), and in the number of IL-2 receptor-bearing cells (p = 0.001). The functional ability of these lymphocyte subpopulations to proliferate in the presence of PHA was significantly suppressed within 24 h of injury and normalized within 3 weeks of injury. DTH skin testing to Candida, mumps, trichophyton, and PPD antigens was performed within 24 h of injury and resulted in anergic responses in all 10 patients when measured at 24, 48, and 72 h following administration. The overall infection rate was 60%, with the majority of infections occurring within the first 4 days following injury. The results of this study indicate that severe head injury results in suppression of cellular immune function with a corresponding high rate of infection. The possible significance of the decrease in the percentage of helper-inducer T cells and in the number of cells bearing IL-2 receptors following mitogen stimulation is discussed.

The effects of anesthesia and surgery on lymphocyte populations and function in infants and children

A study was designed to test the hypothesis that the lymphopenia caused by surgical stress in children may arise through selective depletion of one or more lymphocyte subsets. Blood samples from 22 children were taken pre- and postoperatively and 6, 12, 24, and 48 hours after surgery. Lymphocyte subsets were identified and counted using monoclonal antibodies and indirect immunofluorescence. By six hours postoperatively, the mean total lymphocyte count had fallen by 1.87 x 10(9)/L (P less than .01); this was largely due to the fall in helper T cells (1.53 x 10(9)/L, P less than .01) and both counts remained depressed for at least 48 hours. The helper:suppressor ratio also fell, from 3.42 to 1.92 (P less than .01), but had recovered by 48 hours. Lymphocyte function as measured by the response to pokeweed mitogen and concanavalin A was also reduced six hours postoperatively. These changes were independent of age. Major surgery in infants and children causes a selective reduction in helper T lymphocyte numbers, helper:suppressor ratio, and lymphocyte function. This suggests that immune competence in the immediate postoperative period in children is reduced, as it is in adults. The duration of this and its relationship to infection are not yet known.

Reduction in HLA-DR, HLA-DQ and HLA-DP expression by Leu-M3+ cells from the peripheral blood of patients with thermal injury

Monocytes that bear HLA Class II antigens, such as HLA-DR, HLA-DQ, or HLA-DP, are obligatory for many cell-mediated immunological processes. Patients with thermal injury suffer from hypoimmunity and are at risk for developing life-threatening septic episodes. To determine whether an alteration in expression of HLA Class II antigens is involved in the defect, monocytes from the peripheral blood of burn patients and controls were double-stained with anti-Leu-M3 and either anti-HLA-DR, HLA-DQ, or HLA-DP monoclonal antibodies. As analysed by flow cytometry the percentage of Leu-M3+ monocytes from the peripheral blood from patients and controls was the same. The percentage of Leu-M3+ monocytes bearing the HLA Class II antigens and the density of antigen on the monocytes, however, was significantly reduced post-burn compared with controls. In nearly all cases these changes were detected as early as 24 h post-burn before any drug therapy was implemented. In-vivo re-expression of normal levels of HLA Class II coincided with patient recovery. In-vitro exposure of post-burn Leu-M3+ cells to IFN-gamma for 72 h restored HLA Class II expression to control levels. It is possible that the reductions in HLA Class II expression may be involved in the general immunosuppression that follows thermal injury.

Evidence of a plasma-mediated "window" of immunodeficiency in rats following trauma

The etiology of immunodeficiency following trauma was investigated. Plasma collected from Fischer rats 1-8 hr following a 40% surface area thermal injury (TI) displays immunosuppressive activity (ISA). Peak ISA (4 hr) exceeded 90% inhibition of Con A3-induced proliferation of normal spleen cells. Splenic macrophage IL-1 secretion and NK activity are also inhibited by 4-hr TI plasma. Most importantly, these same cellular immune functions decline in rats by 4 hr following TI. After a further decline by 16 hr (IL-1 = 19.8% and NK activity = 40% of normal), these cellular immune functions rebound toward normal values by 2 days following TI. Thus, ISA in plasma is both temporally and functionally linked to the cellular immune defects observed. Sham-treatment rats display a similar, although less marked, pattern of plasma-linked transient cellular immune defects indicating a role for stress in these responses. ISA is abolished by mild heat (56 degrees C for 30 min) and wholly contained in the greater than 10-kD fraction of plasma. Together, these results provide evidence that previously unrecognized molecules in plasma induce a "window" of immunodeficiency early following trauma.

Ranitidine for prevention of postoperative suppression of delayed hypersensitivity

Cell-mediated immunity was assessed by skin testing with seven delayed-type common antigens in 20 patients undergoing major abdominal surgery and in 20 nonoperative control subjects. The 20 surgical patients were randomized to perioperative ranitidine (50 mg every 6 hours for 72 hours) or no ranitidine. The 20 control subjects received either no ranitidine or ranitidine in the same dosage as the surgical patients. Skin tests were performed 2 days before and 1 day after operation with the same time schedule in the control subjects. Postoperatively, the diameter of the positive skin test area decreased in each of 10 patients without ranitidine (p less than 0.006) but increased in 9 and was unchanged in 1 of the ranitidine-treated patients (p less than 0.01). The skin test changes were similar during the two tests in ranitidine-treated surgical patients and the nonoperative control subjects. Ranitidine did not amplify the response in the nonoperated group. The potential role of histamine blockade in reversal of other aspects of postoperative immunosuppression and reduction in the risk of infection should be explored.

Spontaneous Ig secretion and DNA synthesis in lymphoblastoid B cells appearing after surgery

A state of immunosuppression or immunodeficiency has been described after surgical trauma. Cellular immune functions are more heavily affected. At present the relationship between these abnormalities and the increased incidence of infections in surgical patients has not been clarified. The activation of the humoral compartment and the appearance of lymphoblastoid B cells spontaneously secreting IgG and IgA have been observed in surgical patients. These cells are a marker of a recent antigenic exposure. In this study the kinetics of appearance of this B cell subset and the relationship between spontaneous Ig secretion and DNA synthesis have been analysed in six cholecystectomized patients. A peak of spontaneous IgG and IgA secretion is evident 5 and 7 days after the intervention. In some patients (two out of six) the appearance of lymphoblastoid B cells is cyclical. A second wave of spontaneous Ig secretion becomes evident 14 days after surgery. Double immunofluorescent staining of peripheral blood lymphocytes for BrdU and cytoplasmic Ig (cIg) was employed to demonstrate that a fraction of lymphoblastoid B cells is actively proliferating and that other cells negative for cIg but active in DNA synthesis appear in the circulation. These data confirm the signs of activation observed after elective surgery in otherwise healthy subjects.

The decrease in peripheral blood CD4+ T cells following thermal injury in humans can be accounted for by a concomitant decrease in suppressor-inducer CD4+ T cells as assessed using anti-CD45R

Using single- and two-color fluorescence flow cytometry, 10 thermally injured human subjects were assessed over time for both percentages and absolute numbers of lymphocytes comprising peripheral blood lymphocyte subpopulations. The CD3+ lymphocyte percentage decreased significantly in the early postburn period, and this decrease could be accounted for entirely by a concomitant decrease in the CD4+ lymphocyte percentage. Further, the decline in CD4+ percentage was due to a specific decrease in the suppressor-inducer subset of CD4 as defined using anti-CD45R. No change in the helper-effector subset of CD4 was noted. The percentage of CD8+ lymphocytes did not change significantly at any time postburn nor did subsets of CD8 as defined using anti-CD11. Numerical changes in lymphocyte subsets were dominated by a general lymphopenia occurring on Day 4 following injury. However, suppressor-inducer (CD4+/CD45R+) T cells also decreased significantly on postburn Day 1. These results further elucidate phenotypic changes in immunoregulatory subsets following major injury and suggest a possible basis for depressed autologous mixed lymphocyte responsiveness of burn patient T cells, one of the functional immunologic defects associated with severe injury.

Evaluation of E and EAC rosette-forming cells in patients with thermal injuries

Thermal injuries lead to changes in both the cell-mediated and humoral responses of the patient. This study was undertaken to assess these responses in the post-burn period and also to see if bacterial infection altered these responses. It has been concluded that alterations in the cell-mediated and humoral immune responses following thermal injuries are altered by infection and consequently are also important in the healing process.

A systematic study of host defense processes in badly injured patients

A prospective study of factors predisposing to infection in badly injured patients has disclosed: the dominant roles of two specific parameters: monocyte antigen presenting capacity, and opsonic capacity of diluted serum; the potential value of further assessment of: the predictive value of plots of activated T-cells/total T-cells versus monocyte antigen presenting capacity, the apparent protective effect of the ability to sharply increase specific IgM in response to infection, and the apparent protective effect of cytomegalovirus (CMV) infection in the first 28 days after injury against major bacterial infection; the lack of value of analysis of other T- and B-cell subsets in such patients; and the need to clarify CMV and transfusion status with respect to interpretation of such data. The specific role of variable transfusion and of specific serum immunoglobulins will require further and more discriminating study.

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

Depression of cell-mediated immunity in patients following severe traumatic injury has been well documented in vitro and in vivo. However, the exact mechanism of this defect is still controversial. In this study, we have investigated the ability of injured patients' peripheral blood mononuclear cells (PBMC) to produce two important immunoregulatory molecules, interleukin 1 (IL 1) and interleukin 2 (IL 2). Eighteen traumatic injury patients were studied during the course of their hospital stay and their results compared with a group of 18 normal age- and sex-matched controls. The results showed the following. (1) Production of IL 2 by normal PBMC in response to optimal doses of mitogen may vary with sex as well as age. (2) Adherent mononuclear cells from trauma patients produced at least as much IL 1 as normals. (3) IL 2 production, however, was markedly suppressed (normals, 1.6 +/- 0.2 U; traumatic injury, 0.6 +/- 0.1 U; P = 0.001) and persisted for as long as 50 days postinjury. OKT4+ cells were not significantly decreased at any time, nor were OKT8+ suppressor/cytotoxic cells increased at any time. Decreased IL 2 production in patients treated with steroids or those who were septic was not different from that in those patients who were not treated with steroids or were not septic. These results suggest that the cause of the defect in IL 2 production in traumatic injury patients is not related to a lack of the IL 1 signal, producer T cells, or Ia+ monocytes or to increased suppressor T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Suppression of natural killer-cell function in humans following thermal and traumatic injury

Depressed cell-mediated and humoral immune functions have been reported to occur following severe thermal and traumatic injury. In this study we have questioned whether another immune function, natural killing (NK), is also disturbed in these injured patients. Twenty-two thermally injured patients with burns ranging from 5 to 75% of the total body surface area and 15 traumatically injured patients with injury severity scores ranging from 9 to 56 were followed postinjury and compared to 29 age-matched controls. NK activity was measured as the percentage cytotoxicity in chromium-51 release assays with K562 target cells. The more severely burned patients had significantly depressed NK activity for the 40-day period following injury that remained reduced for the duration of the study. Patients with lesser burns had reduced NK-cell function for the initial 10-day period postburn that returned slowly to the normal range. Traumatically injured patients had depressed NK-cell function during the 3- to 6-day period postinjury. The percentage of cells bearing phenotypic markers for the groups in which NK cells are found was either normal or elevated in these patients. A correlation was found between NK activity and interleukin 2 generation by mononuclear cells from these patients. In order to investigate the mechanism of NK suppression in these patients, NK-cell function was studied following the infusion of cortisol, epinephrine, and glucagon into volunteer subjects in amounts known to reproduce serum levels seen following injury of moderate severity. NK-cell function was reduced an average of 66% following infusion, suggesting that the inhibition of NK-cell function seen in patients may be mediated by the stress response to injury.