Effect of burn injury, mechanical trauma, and operation on immune defenses

Effect of a BIOcocktail on the Immune Response at the Early Postoperative Period in Mice

Since human subjects and laboratory animals may develop impaired immune response during surgery and the postoperative period, efforts have been made to preserve normal immune functions following surgery by the administration of nutritional supplements and probiotics. The present study was designed to examine the effect of a new nutritional supplement, BIOcocktail, on immune parameters in mice exposed to surgery. Forty mice were assigned to 4 groups containing 10 animals each. Two control groups (with and without subsequent sham laparotomy) were given tap water for 45 min every day for 2 weeks. The remaining 2 groups, with and without laparotomy, received BIOcocktail given orally for the same period of time. The proliferative response of splenic cells (splenocytes) stimulated with phytohemagglutinin (PHA), concanavalin A (Con A) and lipopolysaccharide (LPS) was determined by [3H]thymidine uptake. Cytokine levels were measured in splenocyte supernatants and sera using enzyme-linked immunosorbent assay (ELISA) kits. Natural killer cell activity of splenocytes was evaluated by 51Cr-release assay. Laparotomy, without BIOcocktail administration, was followed by a decreased proliferative response of splenocytes to PHA, Con A, and LPS and an increase in interleukin (IL)-6 serum level. In addition, a decreased secretion of IL-1beta, IL-12 and tumor necrosis factor (TNF)-alpha by the splenocytes was observed. Mice treated with BIOcocktail before laparotomy maintained a preoperative level of splenocyte proliferative response and serum concentrations of IL-12. It is concluded that BIOcocktail administered to mice for 2 weeks before operation resulted in the preservation of T- and B-cell proliferative response to mitogens and in the prevention of postoperative decrease in IL-12 serum level.

Thermo-wrap technology preserves normothermia better than routine thermal care in patients undergoing off-pump coronary artery bypass and is associated with lower immune response and lesser myocardial damage

OBJECTIVE

Perioperative hypothermia might be detrimental to the patient undergoing off-pump coronary artery bypass surgery. We assessed the efficacy of the Allon thermoregulation system (MTRE Advanced Technologies Ltd, Or-Akiva, Israel) compared with that of routine thermal care in maintaining normothermia during and after off-pump coronary artery bypass surgery.

METHODS

Patients undergoing off-pump coronary artery bypass surgery were perioperatively and randomly warmed with the 2 techniques (n = 45 per group). Core temperature, hemodynamics, and troponin I, interleukin 6, interleukin 8, and interleukin 10 blood levels were assessed.

RESULTS

The mean temperature of the patients in the Allon thermoregulation system group (AT group) was significantly ( P < .005) higher than that of the patients receiving routine thermal care (the RTC group); less than 40% of the latter reached 36 degrees C compared with 100% of the former. The cardiac index was higher and the systemic vascular resistance was lower ( P < .05) by 16% and 25%, respectively, in the individuals in the AT group compared with in the individuals in the RTC group during the 4 postoperative hours. End-of-surgery interleukin 6 levels and 24-hour postoperative troponin I levels were significantly ( P < .01) lower in the patients in the AT group than in the RTC group. The RTC group's troponin levels closely correlated with their interleukin 6 levels at the end of the operation ( R = 0.51, P = .002).

CONCLUSIONS

Unlike routine thermal care, the Allon thermoregulation system maintains core normothermia in more than 80% of patients undergoing off-pump coronary artery bypass surgery. Normothermia is associated with better cardiac and vascular conditions, a lower cardiac injury rate, and a lower inflammatory response. The close correlation between the increased interleukin 6 and troponin I levels in the routine thermal care group indicates a potential deleterious effect of lowered temperature on the patient's outcome.

Management of patients undergoing splenectomy in an Irish teaching hospital: impact of guidelines

INTRODUCTION

Overwhelming post-splenectomy infection (OPSI) has a 50-70% mortality rate and carries a lifetime risk for the asplenic patient. Specific British guidelines have been developed to reduce its incidence.

AIMS

To determine whether British guidelines were being followed in our own institution and what impact they had on overwhelming post-splenectomy infection.

METHODS

Retrospective chart review of 100 splenectomies performed by Department of Surgery, Beaumont Hospital from January 1990 to January 2000.

RESULTS

Twenty per cent of patients were discharged without any recommended vaccinations. Prophylactic antibiotics were not prescribed in 53% of patients. Just 12% of charts document a verbal explanation of the complications and management of asplenia to the patient. Overall septic mortality was 12%, of whom 8% died in hospital and 4% after discharge.

CONCLUSION

Management of the asplenic patient has improved but is far from complete. A central register of asplenic patients and national asplenic guidelines should be established in Ireland to ensure optimum patient care.

Timing of vaccination does not affect antibody response or survival after pneumococcal challenge in splenectomized rats

BACKGROUND

Pneumococcal vaccination after splenectomy for trauma decreases the incidence of overwhelming postsplenectomy infection. The optimal timing of vaccination has not been established. This study was conducted to determine whether timing of vaccination after splenectomy affects antibody response or survival after pneumococcal challenge.

METHODS

Sprague-Dawley rats were used for all experiments. Control rats (n=30) were divided into three equal groups and underwent splenectomy followed by sham vaccination 1, 7, or 42 days after splenectomy. Treated rats (n=66) were divided into three equal groups and underwent splenectomy followed by vaccination with polyvalent pneumococcal vaccine 1, 7, or 42 days after splenectomy. All rats then underwent intraperitoneal Streptococcus pneumoniae inoculation with the predetermined lethal dose for 50% of the population 10 days after vaccination. Rats were observed for a 72-hour period after inoculation, and mortality was recorded. Immunoglobulin G and immunoglobulin M antibody titers were determined before vaccination and before inoculation to determine antibody response.

RESULTS

Mortality was greater in the control group than in the treatment group (21 of 30 [70%] vs. 2 of 64 [3%]; p < 0.01). There were no differences in mortality within either the control group (1 day, 6 of 10; 7 days, 7 of 10; 42 days, 8 of 10; p=0.62) or the treatment group (1 day, 0 of 21; 7 days, 0 of 21; 42 days, 2 of 22; p=0.14). Immunoglobulin G and immunoglobulin M antibody responses were greater in vaccinated than in nonvaccinated rats. There was no effect of timing of vaccination on antibody response.

CONCLUSION

Pneumococcal vaccine reduces mortality from postsplenectomy infection. Timing of vaccination after splenectomy does not affect survival from a pneumococcal challenge or antibody response in rats. This study supports the practice of administering vaccine within 24 hours of splenectomy when vaccine cannot be administered before surgery.

A longitudinal study of C3, C3d and factor Ba in burn patients in Hong Kong Chinese

A longitudinal study of serum C3, C3d and fragment Ba was carried out in 53 burn patients of Chinese origin whose total burn surface area ranged from I to 45%. Complement C3 was found to be activated on or before day 7 post-burn. The sharp increase in C3d suggested an acute inflammatory response. In addition factor Ba was increased in these patients, suggesting that the alternative pathway was also activated following thermal injuries. The fluctuations of C3, C3d and Factor Ba observed about 1 year after injury suggested chronic inflammation associated with long term of outcome of healing in the burn sites.

Chemiluminescence response of whole blood in patients undergoing urological operations

Polymorphonuclear leukocytes (PMNs) are one of the most important components of the defence mechanisms against bacterial infection. The functions of PMNs are believed to be impaired in patients during the perioperative period. Bactericidal function of PMNs was investigated together with the luminol-dependent chemiluminescence (CL) reaction of whole blood in 23 patients, 12 undergoing open surgery and 11 undergoing endoscopic surgery. Blood samples were collected one day before surgery (day -1) and 2 hours (day 0), 24 hours (day 1) and 7 days (day 7) after surgery. Counts of whole white blood cells (WBCs), PMNs and lymphocytes were not different between the two surgery groups. CL responses in the open surgery group were increased on days 0, 1 and 7. In the endoscopic surgery group, CL response was increased on day 1, but not on day 0 or day 7. These results suggest that the PMN function during the perioperative period was not impaired, but increased just after surgery, mainly due to an increasing number of WBC caused by the surgical intervention.

Lymphocytic subpopulation changes after open and laparoscopic cholecystectomy: a prospective and comparative study on 38 patients

Up to now it has been unclear whether laparoscopic surgery has fewer immunosuppressive effects than traditional laparotomic procedures. In a series of 38 patients affected by symptomatic gallstone disease and operated on either by laparoscopy (group 1) or by traditional open surgery (group 2), we determined the postoperative changes in lymphocyte subpopulations up to postoperative day (POD) 30. We collected 15 ml of venous blood from all patients in both groups on the day before surgery and on POD 1, 7, 15, and 30. A control group (group 3) comprised 56 healthy volunteers; the control group was used only to ensure that baseline values were totally comparable with a normal population; only one blood sample was obtained from the subjects in group 3. Patients undergoing open cholecystectomy had a significant decrease in total lymphocyte count on POD 1. Basal levels of lymphocyte subpopulations did not differ significantly in the study and control groups. No differences were found in the preoperative lymphocyte cell counts in the two groups who underwent cholecystectomy. Pan-T cells (CD3) showed a statistically significant marked reduction throughout the observation period. The counts of helper (CD4), suppressor (CD8), and natural killer NK (CD16) T cells were reduced on POD 1; the NK cell (CD16) count remained low until POD 30, B lymphocytes showed no postoperative reduction. In patients who underwent laparoscopic cholecystectomy, a significant postoperative decrease in total lymphocyte count, and in CD3, CD4, and CD8 subpopulations was observed on day 1 only. There was no reduction in CD16 and CD19 subpopulations. A comparative statistical analysis of lymphocyte subpopulations in the two groups was carried out: In the open cholecystectomy group, compared with the laparoscopy group, CD3, CD4, CD8, and CD16 lymphocyte subpopulations showed marked reductions at different time points. In particular, statistically significant differences were found in CD3 levels from POD 1 through POD 30, in CD4 from day 1 through day 7, and in CD8 and CD16 only on day 1.

Reprioritization of liver protein synthesis resulting from recombinant human growth hormone supplementation in parenterally fed trauma patients: the effect of growth hormone on the acute-phase response

BACKGROUND

One of the major components of the metabolic response to severe trauma is the alteration in concentrations of a large number of plasma proteins referred to as acute-phase proteins (APP). The principle mediators of these liver-synthesized APP are mainly the cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha).

METHODS

We have measured the plasma levels of IL-6, TNF alpha, and 20 APP in 24 adult, severely injured, hypermetabolic and highly catabolic patients with multiple injuries within 48-60 hours after injury, when they were receiving maintenance fluids without calories or nitrogen, and subsequently during 7 days of total parenteral nutrition with (n = 12) or without (n = 12) recombinant human growth hormone supplementation (rhGH, 0.15 mg/kg/d).

RESULTS

Baseline positive APP due to severe trauma include C-reactive protein (CRP), alpha-1 antichymotrypsin, alpha-1 acid glycoprotein, alpha-1 antitrypsin, fibronectin, and factor B. Negative APP include IgG, IgM, complement-3, prealbumin, transferrin, ceruloplasmin, and albumin. Except for CRP, alpha-1 antichymotrypsin, and albumin, all the APP levels increase during 7 days of nutritional support. Plasma levels of cytokines IL-6 and TNF-alpha, although initially markedly increased after injury, decrease with parenteral refeeding. There is a linear correlation between CRP and IL-6 levels and also between the transport proteins prealbumin and transferrin. Trauma-induced increases in CRP and IL-6 levels decreased with nutrition alone, but did not change with rhGH supplementation. An immunosuppressed state of injury is evident from the decreased immunoglobulin levels (IgG, IgM, IgA) in the trauma patients. Total parenteral nutrition alone increases the immunoglobulin levels to normal. However, with adjuvant rhGH, only IgA levels are normalized.

CONCLUSIONS

Adjuvant rhGH therapy does not attenuate the reprioritization of acute liver protein synthesis and results in only limited restoration of host defenses. The clinical implications of these findings await further study.

Effect of surgical trauma on splenocyte and peritoneal macrophage immune function

Although previous studies have shown that simple laparotomy produces a depression in peritoneal macrophage (Mphi) antigen presentation capacity, it remains unknown whether the adverse effects of laparotomy are limited to peritoneal Mphi or whether such an insult also affects splenocyte immune function. To study this, mice were anesthetized and a 1-inch midline abdominal incision was made, followed by abdominal closure. At 2 and 24 hours after the surgical procedure, the animals were killed, splenocyte cultures established and stimulated for 48 hours with concanavalin A (2.5 micrograms/mL), while peritoneal macrophage cultures were stimulated with LPS (10 micrograms/mL). The proliferative capacity of the splenocytes, as well as their ability to release interleukin-2 and interleukin-3, was markedly decreased at 2 as well as 24 hours after laparotomy. Furthermore, the release of interleukin-6 by splenic and peritoneal macrophages from animals that underwent laparotomy were also significantly depressed at both 2 and 24 hours. These results support the concept that surgical stress in the form of midline laparotomy per se is sufficient to produce a significant impairment in cell-mediated immunity, thus setting the stage for increased incidence of postoperative complications.

Postoperative immunological function and jaundice

The effects of operative trauma and obstructive jaundice on systemic immunity were studied in a rat model, using the delayed-type hypersensitivity response to 2,4-dinitro-1-fluorobenzene as a measure of systemic immune responsiveness. Midline laparotomy caused a significant decrease in the mean(s.e.m.) delayed-type hypersensitivity response 1 week after operation (4.6(1.3) versus 19.0(2.2) per cent for controls). The response returned to control levels by 2 weeks (14.6(3.1) per cent). Common bile duct ligation and division resulted in a significantly depressed hypersensitivity response at 2 and 3 weeks (6.8(2.0) and 8.4(1.6) per cent respectively). The expected decrease in the response at 1 week in these animals was not observed (mean(s.e.m.) 12.7(2.7) per cent), suggesting a possible role for the normal liver in the induction of postoperative immune depression. Impaired function of the reticuloendothelial system was induced in non-jaundiced animals by Kupffer cell ablation following intraportal infusion of lambda-carrageenan. A similar prevention of postoperative immune hyporesponsiveness was observed (mean(s.e.m.) 10.4(1.0) versus 10.4(1.6) per cent for controls). Hepatic Kupffer cells play an important role in the induction of postoperative immune depression.

Human neutrophil and macrophage chemokinesis induced by cardiopulmonary bypass: loss of DAME and IL-1 chemotaxis

Cardiopulmonary bypass (CPB) induces both cellular immunosuppression and an inflammatory response. In an effort to better characterize CPB-induced immune dysfunction, we examined the chemotaxic ability of human granulocytes and macrophages to D-Ala2-Met-enkephalin (DAME) and interleukin (IL)-1 alpha with computer-assisted microscopic image analysis before, during and after CPB. Spontaneous granulocyte and macrophage activation increased from 6% and 8% (before) to 52% and 44% (during) and then 39% and 31% after (38 h) CPB, respectively. These activated cells, characterized by conformational changes and locomotion, exhibited chemokinesis. Furthermore, no direct response to either DAME or IL-1 alpha was observed in the bypass and postoperative specimens. Cellular velocity was 0.14 and 0.07 microns s-1 for control spontaneously activated granulocytes and macrophages, respectively, and equal to the velocity observed for DAME and IL-1 alpha exposed cells, during and after CPB. CPB-unexposed cells, influenced only by the chemotaxic agents, exhibited a 3-4-fold increase in their velocity. Additionally, the migratory path of the activated cells obtained during and after CPB exhibited chemokinesis, rather than chemotaxis, when placed in a concentration gradient of either signal molecule. Cells exposed to fentanyl, the anesthetic agent, exhibited the same behavior as controls, as did those treated with morphine sulphate. However, at higher concentrations (> or = 10 ng ml-1) fentanyl and morphine reduced granulocyte and macrophage activity, demonstrating that CPB caused the opposite effect of fentanyl and also that CPB exposure overcame the pharmacological inhibitory effect of the mu opiate ligands.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of surgery on in-vitro cytokine production by human monocytes

Surgery leads to significant modulation of the immune system, in which cytokines play a major role. Circulating interleukin 6 (IL-6) and IL-1 have been reported following surgery whereas tumor necrosis factor alpha (TNF-alpha) is only found in gut ischemia-associated surgery. We have investigated the consequences of surgery on in-vitro cytokine production by human monocytes stimulated by lipopolysaccharide (LPS) and staphylococcal toxic shock syndrome toxin-1 (TSST-1). Comparisons were made between the responsiveness of cells obtained the day before (D-1), during (D0) and after (D1, D2, D3) surgery. Patients undergoing abdominal aortic surgery (N = 9), carotid surgery (N = 4) and spinal surgery (N = 4) have been studied. A significant decrease of TNF-alpha, IL-1 beta and IL-1 alpha production by monocytes prepared from blood samples taken during the surgery was noticed, whereas IL-6 production was not significantly modified. On D2 a significant increase of monocyte responsiveness was observed and levels of cytokine productions rose back to initial values by the end of the follow up. The diminished in-vitro cytokine production observed during surgery might be the consequence of the effects of anaesthetic drugs, whereas the enhancement observed on D2 might reflect the surgical stress, leading to in-vivo priming of circulating monocytes.

The immunologic response to thermal injury

Thermal injury is associated with altered immune defense. Extensive and deep thermal injuries lead to depressed immune defense function with both cellular and humoral defense affected. There is an intricate interaction between various components of the immune system. The altered specific immune response is seen as a depressed ability to produce active rosette-forming cells. Depressed stimulation of lymphocyte proliferation as well as the mixed lymphocyte response have also been recorded following burns. These effects are modulated by the release of kinins, prostaglandins, anaphylatoxins, superoxides, and leukotrienes, all of which can influence the inflammatory response following thermal injury. The humoral immunity is altered as seen by decreased levels of immunoglobulins, activation of complement with release of anaphylatoxins, and formation of membrane attacking complexes leading to inflammation and cytolysis. The immune response to burns is also affected by factors other than this injury, such as nutrition or diseases such as diabetes mellitus or disorders of the lymphoproliferative type. The immune response is also influenced by some drugs used for other reasons such as steroids, chemotherapeutic agents, and topical agents used for burn wound care. The immune reaction to a burn is also influenced by the additive effect of superimposed infections. Removal of injured tissue without the need for extensive transfusion will improve the ability of the burned patients to use their immune defense system in a fruitful way.

The risk factors of median sternotomy infection: a current review

Sternal sepsis following median sternotomy is an infrequent yet devastating complication of cardiac surgery, leading to prolonged hospitalization, increased hospital expense, and a high associated morbidity and mortality. The development of sternotomy infection is multifactorial. Numerous prospective and retrospective studies have pointed to a multitude of clinical and perioperative variables as being causative, with as many other studies presenting evidence of the contrary. This has led to confusion about which clinical variables should be modified so as to minimize the individual patient's risk for developing this severe complication. Other less obvious factors also come into play. Malnutrition, whether overt or subclinical, is not uncommon in cardiac patients. Immune competency is affected by operative trauma, as well as a variety of perioperative factors including underlying nutritional status, transfusion, cardiopulmonary bypass, and anesthesia. This creates a complex milieu for the development of postoperative infection. In this review, the multiple risk factors of median sternotomy infection are studied and treatment options briefly discussed.

Alteration of macrophage activity in experimental septic shock in the rabbit

We studied alteration in macrophage activity during experimental septic shock and the effect of the protease inhibitor Trasylol on these alterations. Studies were carried out on three groups of 6 rabbits of each. One group (A) served as a control and in the other two groups (B,C) septic shock was induced using the cecal ligation technique. Group B received i.v. Trasylol prior to and following cecal ligation. The clearance and reticuloendothelial system (R.E.S.) distribution of 125I labelled polyvinyl pyrrolidone (PVP) was used to study macrophage function. PVP was injected into all animals 18 h prior to cecal ligation. For 48 h following the operation, PVP blood levels were repeatedly measured and clearance calculated. The animals were then sacrificed, and total radioactivity of the various organs was measured. In the early stages after cecal ligation a significantly higher PVP clearance rate was noted in groups B and C (P less than 0.01); In the later stages of the experiment, however, group C demonstrated the slowest clearance rate with intermediate values in group B. The highest PVP concentrations were found in the liver and spleen. A significantly higher PVP concentration was noted in the spleen of the animals in group A and B as compared to group C (P less than 0.01) while the difference between group A and B was not significant. Our results indicate that septic shock reduces macrophage function as measured by the changes in PVP clearance and distribution. Injections of Trasylol seem to ameliorate these changes. The model of 125I PVP clearance seems to offer a convenient, valid and informative model for measurement of macrophage activity in pathological conditions.

Sternotomy infection: poor prediction by acute phase response and delayed hypersensitivity

Two hundred twenty-one consecutive adult cardiac surgical patients were examined prospectively for nutritional protein state, acute phase protein response, and delayed hypersensitivity reaction in an attempt to identify patients at high risk for the development of sternal wound infection, which occurred in 6 patients (2.7%). There was no significant correlation between preoperative nutritional protein concentrations (retinol-binding protein, prealbumin, and transferrin) and acute phase protein levels (C-reactive protein, alpha 1-acid glycoprotein, and complements B and C3), nor a statistically significant relationship between nutritional state or acute phase protein response and the development of sternal infection. Preoperative complement C3 levels were elevated, however, in 80.0% of those in whom sternal infections developed compared with 30.6% of those with well-healed wounds. Similarly, postoperative concentrations of alpha 1-acid glycoprotein were elevated in 80.0% of those in whom sternal infections developed compared with 28.6% of those with well-healed wounds. There was no correlation between delayed hypersensitivity and the risk of sternal infection, nor between preoperative nutritional protein and acute phase protein values. Seventy-three percent of patients were anergic on postoperative day 2. Stepwise logistic regression showed that age, body weight, preoperative intensive care unit stay, repeat median sternotomy, internal mammary artery grafting, postoperative hemorrhage, and postoperative cardiac arrest correlated with the development of sternal infection, whereas transfusion requirement, reexploration for bleeding, and the operation performed did not. We conclude that routine delayed hypersensitivity testing is of no value in predicting high-risk cardiac surgical patients when the anergy battery is placed on the preoperative day. Although statistically insignificant, possibly due to the small number of patients in whom sternal infection developed in this study (type II error), a larger study might find preoperative complement C3 and post-operative alpha 1-acid glycoprotein levels to be predictive of patients at risk for the development of sternal wound infection. The final logistic model for the predicted risk 2%) of sternal wound infection is: PREDSWC = exp(EQ)/1 + exp(EQ) where EQ = (0.38 x age) + (0.24 x weight) + (5.42 x preop ICU) + (4.39 x redo) + (7.14 x IMA) + (4.49 x hemorrhage) + (8.81 x arrest) - 62.72, and where preop ICU, redo, hemorrhage, and arrest are defined as yes (1) or no (0), IMA-is defined as 0, 1, or 2, age is in years, and weight is in kilograms.

Distribution of lymphocytes in intermingled skin grafts

Chinese intermingled skin grafts of allogenic material interspersed with small autogenic islets heal permanently with no signs of a rejection reaction. A study of the T-helper and T-suppressor cells in the region of the autogenic islets and the remaining allodermis revealed a distinctly greater frequency of these cells in the islets, with marked massing of the cells between the autoepithelium and the autodermis. Histologically it could be shown, that the Langerhans' cells grow over the allodermis together with the epithelium, although compared with the autogenic islets their number in the newly formed epidermis remained reduced.

Trauma peptide induction of lymphocyte changes predictive of sepsis

Post-trauma immunosuppression is characterized by T-cell subpopulation changes and the presence of a low molecular weight suppressive active peptide (SAP), which suppresses T-cell blastogenesis and neutrophil chemotaxis. This study evaluated post-trauma T-cell antigens and suppressive active peptide/T-cell interactions to determine if the suppressive active peptide concentrations predictive of sepsis can cause changes in antigen expression predictive of sepsis. Human lymphocyte markers and differentiation antigens were analyzed post-trauma using flow cytometry for markers predictive of sepsis. Changes induced by purified suppressive active peptide incubated with normal human lymphocytes were similarly analyzed by flow cytometry. SAP concentrations for incubation were chosen which correlated with concentrations in patients developing clinical sepsis. Significant T-cell changes in patients who developed sepsis include: decreased total T-cells, decreased helper cells, decreased natural killer cells, increased Ia expressing mononuclear cells, increased activated T-cells, (L22) and increased IL-2 expressing cells (TAC). Suppressive active peptide can activate T-cells and cause significant increased expression of IL-2 receptors and natural killer cells. Other T-cell changes following trauma predictive of sepsis seem to occur independent of in vitro incubation with suppressive active peptides. IL-2 expressing cells are known to be more readily suppressed by the suppressive peptide. Suppressive peptide activation and subsequent inhibition of T-cells suggests a potential way to explain suppressive peptide-induced immunosuppression following trauma.

Photoimmunology: the mechanisms involved in immune modulation by UV radiation

Ultraviolet radiation (UVR) may be the most prevalent agent that man encounters in his environment. As a result, certain biological adaptations take advantage of the beneficial effects of UVR exposure, e.g. the photoactivation steps involved in vitamin D metabolism. In this regard, UVR plays an important role in maintaining our good health; however, it must be noted that UVR is potentially the most harmful naturally occurring agent in our environment. Thus, it appears that several mechanisms have evolved to protect us against the detrimental effects of UVR overexposure. Although epidermal melaninization or "tanning" may be the most obvious example of these processes, we would argue that adoptive mechanisms within the immune system also provide protection against UVR-induced skin damage. It is now known that UVR affects the distribution and functional activities of various immunocompetent cells within the skin, as well as modifying the production of inflammatory and hematopoietically active cytokines. This review will focus on the known mechanisms involved in the immune modulatory effects of UVR and how adoptive immune responses to UVR-induced skin damage contribute to specific pathological processes.

Consequences of blood loss on growth of artificial metastases

Previous studies have shown that lung metastases from a nonimmunogenic sarcoma (LS175) in BN (homozygous for RTln) rats were stimulated by blood transfusions. Enhanced growth was also observed after abdominal surgery combined with allogeneic blood transfusions while syngeneic blood transfusions had no effect. These experimental findings have been confirmed in retrospective clinical studies. The allogeneic blood transfusion effect may be avoided in cancer patients by autologous blood transfusions although this implies blood donation before surgery. The aim of the present study was to investigate the effect of blood loss before surgery on formation ('take') of lung colonies, and on the outgrowth of established metastases in the BN rat model. These aspects of tumour behaviour were also investigated in rats undergoing surgery, or receiving blood transfusion, or both, after blood loss. The results indicate that blood loss has a profound stimulating effect on the growth of established metastases, but not on the 'take' of tumour cells. This stimulating effect was also present when blood loss was combined with surgery, while previously surgery alone was found to have no effect. Allogeneic and syngeneic transfusions in combination with blood loss both had a strong stimulating effect on growth of established lung metastases. The results indicate that blood loss may be an important factor in determining the outcome of metastatic growth.

Influence of surgery on the responsiveness of blood lymphocytes in patients with advanced cancer

The effect of surgery on peripheral blood mononuclear cell responsiveness to mitogens and suppressor cell (SC) activity assessed in a concanavalin A (ConA) assay were studied in patients with stage 0 and stage III-IV cancer. Patients were exposed to a similar surgical trauma the same type of anaesthesia, and to no pre- and early postoperative radio- or chemotherapy. A more pronounced postoperative decrease in the lymphocyte count, responsiveness to phytohemagglutinin (PHA) and ConA, and in the SC activity was found in the nonadvanced than advanced cancer group. These findings point to an impaired mobilization and distribution capacity of circulating lymphocytes in patients with advanced neoplastic disease.

The influence of surgical operations on components of the human immune system

Surgical operations have been shown to cause a variety of immunological disturbances in man both in vivo and in vitro. With few exceptions the overall picture is one of a generalized state of immunodepression in the postoperative period. The implications of these observations are that host defences may be compromised by surgical procedures, thus providing a 'fertile soil' for bacterial invasion and tumour cell metastasis at the very time when risks from invading pathogens and viable tumour cells are maximal. We have studied the effects of surgical operations on the immune system in 35 patients with benign disease. Surgical procedures were classified as either minor (n = 15) or major (n = 20). A panel of monoclonal antibodies was used to identify peripheral blood lymphocyte subpopulations and analysis was performed using flow cytometry. Simultaneous estimations of plasma alpha-1 proteinase inhibitor (alpha-1-PI), alpha-2-macroglobulin (alpha-2-M), alpha-2-pregnancy-associated glycoprotein (alpha-2-PAG) and plasma suppressive activity (PSA) on stimulated allogeneic lymphocytes were performed before operation and on postoperative days 1, 3, 7, 17 and 21. Circulating numbers of all lymphocyte subpopulations fell significantly following surgery, except for B lymphocytes which did not change. The magnitude, and duration of the reduction in cell numbers and the subpopulation affected was significantly related to the degree of surgical trauma, and returned to pre-operative values by postoperative day 7. Changes in alpha-1-PI, alpha-2-M, alpha-2-PAG and PSA were also significantly related to the degree of surgical trauma, and these plasma changes persisted longer than the cellular disturbances. Surgical operations induce a reversible depression of cellular immunity which precedes plasma suppressive activity in its return to pre-operative levels. Immunostimulating agents such as interferon and the interleukins deserve evaluation as prophylactic agents pre-operatively.

Immunologic mechanisms underlying sepsis in the critically ill surgical patient

This article describes the range of immunologic abnormalities that follows accidental and operative trauma. The high rate of infection in critically ill postoperative patients may result from these abnormalities in host defense function. Means to recognize and correct the post-trauma immune deficiencies are discussed.

A burn induced Ly-2 suppressor T cell lowers resistance to bacterial infection

Suppressor T cell activity after major burn injury in a murine model has been well characterized. Suppressor cells have also been demonstrated in patients after major burn, and suppressor cell activity has been temporally correlated with septic episodes. A splenic Ly-2 T suppressor effector (Tse) cell appearing 7 days after a 30% full thickness burn has been identified in a murine model. A rat monoclonal antibody (14-8c3-12) directed against a factor produced by the Tse cell (Tsef) can enhance depressed in vitro mixed lymphocyte reaction (MLR) responses of Day 7 burn spleen cells without enhancing control spleen cell activity. Additionally, 14-8c3-12 can block the suppressive effect of these burn T cells on normal T cells. A cecal ligation and puncture (CLP) model using a 25-gauge needle (LD15) was used to assess the contribution of burn T cells to post-CLP mortality. Normal spleen cells injected into syngeneic recipients followed by CLP did not affect mortality (13%). Burn spleen cells injected into normal recipients enhanced mortality sixfold (90%) after CLP. The effect could be reversed by removing Ly-2 T cells (30% mortality) but not Ly-1 T cells (100% mortality) prior to cell transfer. Simultaneous injection of 14-8c3-12 antibody with burn T cells reduced mortality after CLP significantly (20%). Injection of 14-8c3-12 did not improve survival after CLP in control animals not injected with burn T cells (20%). Ly-2 T suppressor effector cells found in the spleens of mice 7 days postburn enhance the lethality of a purely bacterial septic challenge. A monoclonal antibody to the Tsef can reverse this effect in vivo.

Candida infection in severe burns

Candida infection has become an important cause of morbidity and death in burned or immunosuppressed patients. Two patients with extensive burn complicated with Candida infection are presented, along with the risk factors, diagnostic procedures, and current methods of treatment.

Lymphocyte function in the critically ill surgical patient

Lymphocyte function is commonly altered in critical ill surgical patients. There is controversy whether or not formation of antibodies is impaired; however, cellular immune responses are routinely depressed. Patients who have suffered major surgical or accidental trauma or burns frequently become anergic. Their lymphocytes respond poorly to mitogenic or antigenic stimulation, and serum factors suppressive of lymphocyte activation appear. Mechanisms underlying these abnormalities remain to be defined.

Immunologic status in infants and children following surgery

The investigation of cellular and humoral immunologic parameters (T and B lymphocytes and immunoglobulins) with respect to postoperative infection in children revealed changes in the T lymphocytes in particular. Preoperative complications (ileus, shock, infection), anesthesia and surgery lead to transient immunosuppression. The duration of this T cell suppression is age-dependent; suppression is longest in newborns (up to three weeks on the average) and shortest in older children (one week on the average). IgA and IgG concentrations show only slight abnormal changes; IgM concentrations, however, increase significantly during the postoperative period in all age groups. Prophylactic and therapeutic measures for the prevention of postoperative infections can be considered on the basis of immunologic changes related to surgery.

The effect of surgery and chemotherapy on blood NK cell activity in patients with ovarian cancer

The cytotoxic activity of NK cells in peripheral blood was studied in 15 patients with ovarian cancer Stage III and IV before and after surgery and ten-week intramuscular therapy with thiotepa. An evident decrease in NK activity was found 24 hours after surgery, with a slow return toward normal values within 7-9 days. No differences between patients with explorative laparotomy and with extirpation of the tumor were observed. The mechanism of the decreased NK cytotoxicity remains unknown but there was a concomitant reduction in the number of blood mononuclears. A second drop in NK activity occurred after chemotherapy. It was most likely due to the drug bone marrow depression. No evident correlation between the reduced NK activity and advancement of the disease could be found.

The Hartmann procedure

During a 10-year period, 59 patients had a Hartmann operation for diverticular disease (n = 19), carcinoma (n = 21), anastomotic disruption (n = 5), injury (n = 3) and various other conditions (n = 11). Twenty-two patients (37.3 per cent) died postoperatively. Wound infection or wound dehiscence occurred in 26 patients. Other complications inherent in this operation were colostomy necrosis or retraction (n = 12) and leakage of the rectal stump (n = 3). The mean hospital stay of the surviving patients was 28.4 days. Colorectal continuity was subsequently restored in 12 patients (32.4 per cent) and no difficulties were encountered with this procedure.

Depressed immune response in burn patients: use of monoclonal antibodies and functional assays to define the role of suppressor cells

Recent experimental evidence has suggested that circulating suppressor leukocytes play an important role in mediating the suppression of immunity seen in burn patients. In order to shed further light on the relationship between suppressor cells and depressed cellular immunity 22 patients were studied (mean age 37) who had suffered severe burns of greater than 30% body surface area. Simultaneous studies were performed on 14 control laboratory personnel (mean age 32). Monoclonal antibodies were used to identify T-lymphocyte subsets known to have suppressor/cytotoxic (OKT8) and helper/inducer (OKT4) function, respectively. In addition, serial measurements were made of the response of circulating lymphocytes to the T-cell mitogen phytohemagglutinin (PHA). An inversion of the normal ratio between suppressor/cytotoxic and helper/inducer subsets (normal 0.55:1, postburn 1.4:1; p less than 0.001) occurred soon after burn injury, reached a peak in five to seven days and then returned gradually to normal levels by 14 days. A diminished response of patients' lymphocytes to PHA (57 +/- 10% SD suppression as compared with normal controls at five to seven days) corresponded with high suppressor to helper cell ratios and returned to normal at the same time. Functional assays, which recognize only high levels of activity, demonstrated circulating suppressor cells in nine patients during this same period but became negative by 14 days. These early immunologic modulations were not predictive of morbidity or mortality. Later in the postburn course, systemic sepsis in eight patients was associated with a return of increased suppressor to helper cell ratios and decreased mitogen (PHA) responsiveness. At this time functional assays demonstrated circulating suppressor cells in six patients. Five of these six patients died of sepsis. It was concluded that severe burn injury regularly induces an early transient increase in circulating suppressor cells accompanied by a depression of lymphocyte activation. A later (greater than 14 days postburn) increase in suppressor cells to levels detectable by functional assays is closely correlated with mortality from sepsis.