Association of a circulating immunosuppressive polypeptide with operative and accidental trauma

The release of immunosuppressive factor(s) in young males following exercise

It has been shown that a suppressive protein, acting as an immune suppressor, is generated in animals and humans under particular stresses. However, studies related to immunosuppressive factors in response to the stress resulting from acute exercise are limited. This study compares the effects of pre- and post-exercise human serum on concanavalin A stimulated lymphocyte proliferation of mice. In the present study, blood samples in eight male undergraduates (age 21 ± 0.7 years) were taken before and immediately after ten sets of exercise consisting of 15 free and 30 10-kg loaded squat jumps in each set. The suppression of lymphocyte proliferation was analysed with high pressure liquid chromatography. It was noted from the result of gel chromatography columns that the post-exercise values of the suppression of lymphocyte proliferation, in comparison to corresponding pre-exercise values, were generally greater with significant differences observed in 7.5th-9th min post-exercise eluates (P < 0.05). Such findings suggest that intense eccentric type exercise may lead to generation of immunosuppressive factor(s) in young males.

Is impaired immunity a consequence of surgery in patients infected by the human immunodeficiency virus?

BACKGROUND

Surgery affects immune function adversely in a variety of clinical settings. To date, there are no data assessing immune function in patients infected with the human immunodeficiency virus (HIV) who have had surgery.

METHODS

A retrospective review was performed of 67 patients, of whom 46% were female, who underwent surgery while being treated for HIV infection. These patients were identified from a database collected over a ten-year period. The CD4(+) cell counts were analyzed according to the degree of immunosuppression (> or =500, 200-499, and <200 cells/mm(3), respectively). Viral titers also were assessed.

RESULTS

Of the 17 patients with CD4(+) cell counts >500/mm(3) prior to surgery, 64.7% had unchanged counts after surgery (95% confidence interval [CI] 32.9%, 81.6%), whereas 35.2% of patients had lower CD4(+) counts after surgery (95% CI 14.2%, 61.7%). In patients with preoperative CD4(+) counts between 200 and 500/mm(3), 9.7% (95% CI 2.0%, 25.8%) had their counts decrease to <200 cells/mm(3), whereas in 29% (95% CI 14.2%, 48.0%) of patients, the counts increased to within the normal range. In the most immunosuppressed group (CD4(+) counts <200/mm(3)), 15.8% of patients (95% CI 3.4%, 39.6%) had their CD4(+) counts increase to the intermediate range. In the majority of patients, the viral titers remained unchanged, whereas 18.8% (n = 6) (95% CI 7.2%, 36.4%) had a decline in their titers.

CONCLUSIONS

Surgery does not affect immune function adversely in HIV-infected patients, as judged by CD4(+) cell counts or viral titers.

Biological, histological, and clinical impact of preoperative IL-2 administration in radically operable gastric cancer patients

BACKGROUND AND OBJECTIVES

Surgery induces lymphocytopenia and this decrease of host defenses, related to interleukin-2 (IL-2) endogenous imbalance during postoperative period could promote the proliferation of possible micrometastases and the implantation of surgically disseminated tumor cells. Moreover, tumor infiltrating lymphocytes (TILs), activated by endogenous IL-2 release, are linked to prognosis in cancer patients. The aim of this randomized study is to assess the biological (peripheral blood cells count, related to the grade of immunosuppression), histological (TILs), and clinical (overall and disease-free survival) impact of preoperative low doses administration of IL-2 in patients with radically operable gastric cancer.

METHODS

This prospective study enrolled 69 consecutive patients with histologically proven gastric adenocarcinoma who underwent radical surgery from October 1999 to December 2002 (M/F 39/30; mean age 66; range 42-82) who underwent radical surgery from October 1999 to December 2000. Patients were randomized to be treated with surgery alone as controls (35 patients) or surgery plus preoperative treatment with recombinant human IL-2 (34 patients). We considered the total lymphocyte count and lymphocyte subset (CD4, CD4/CD8) during the preoperative period, before IL-2 administration, and on the 14th and 50th day, peritumoral stromal (fibrosis) reaction, neutrophils, lymphocytes, and eosinophils infiltration in tumor histology, and morbidity disease free and overall survival were evaluated.

RESULTS

Two groups were well matched for type of surgery and extent of disease. All the patients underwent radical surgery plus D2 lymphadenectomy. At baseline, there were no significant differences in total lymphocyte and lymphocyte subsets between groups. The control group showed a significant decrease of total lymphocytes, CD4 cells, and CD4/CD8 ratio at the 14th postoperative day relative to the baseline value. In the control group 65% of patients had a decrease of CD4 under 500 cells/mmc. Instead it has been observed in IL-2 group a significant increase over the control group values of total lymphocytes and CD4 cells (14th total lymphocytes and CD4: IL-2 vs. control P < 0.05). Moreover in this group only 15% patients had CD4 under 500 cells/mmc. This difference, in CD4 count, is significant even at the 50th postoperative day (P = 0.006). IL-2 group showed lower postoperative complications (2/34 vs. 11/35; P < 0.05), and higher lymphocyte/eosinophil infiltration into the tumor (P < 0.0002). Median follow-up was 26 months (range 10-48) and median overall and disease-free survivals were longer, even if not significantly, in the IL-2 group than in the control arm (P = 0.07 and P = 0.06 respectively).

CONCLUSIONS

This randomized study would suggest that a preoperative immunotherapy with IL-2 is a well-tolerated treatment able to prevent surgery-induced lymphocytopenia. IL-2 seems to neutralize the immunosuppression induced by operation and so to stimulate the host reaction against tumor tissue (lymphocytes/eosinophils infiltration). Furthermore IL-2 seems to have an impact on clinical course reducing morbidity of surgery and ameliorating overall and disease-free survival.

Phase IB study on prevention of surgery-induced immunodeficiency with preoperative administration of low-dose subcutaneous interleukin-2 in gastric cancer patients

BACKGROUND AND OBJECTIVES

Low count of total and T helper lymphocytes predicts a poor prognosis in cancer patients and surgical trauma can worsen cancer-related immunodeficiency. Aim of this phase IB study is to verify toxicity and biological effects of interleukin-2 (IL-2) at 9 million IU/day subcutaneously (sc.) administered one, two or three preoperative days in patients with gastric cancer undergoing radical surgery.

METHODS

Absolute value of total and T-helper (CD4) lymphocytes were measured at baseline and at 7th, 14th, and 50th postoperative days in 12 gastric cancer patients, who preoperatively received IL-2 at 9 million IU/day sc. as follows: group A (4 pts) 1-day; group B (4 pts) 2-days; group C (4 pts) 3-days administration. T and total lymphocytes count were recorded and retrospectively analyzed in a historical control-group of 22 consecutive patients, age and stage-matched.

RESULTS

Toxicity consisted of fever grade I. In group A (1 day) T helper lymphocytes count decreased at 7th and at 14th postoperative day; in group B (2 days) and group C (3 days) no decrease of neither total nor T helper lymphocyte count occurred postoperatively, whereas in the historical group these parameters decreased significantly postoperatively and recovered only at 50th day.

CONCLUSIONS

Two- and three-day schedules of sc. IL-2 preoperative administration at 9 million IU/daily prevented postoperative lymphocytopenia, whereas one-day administration did not. Since the IL-2 dose was so tolerable, that it could be given safely as outpatient, based on the previous results on survival observed in colorectal cancer patients with 3-days schedule we suggest that a 3-day schedule of Interleukin-2 as outpatient preoperative treatment seems advisable for further studies in gastric cancer patients.

Severity, time, and beta-adrenergic receptor involvement in surgery-induced immune alterations

Although investigations of surgical stress in animals have reported immune alterations, surprisingly little is known about the variables or mechanisms contributing to the effect. Thus, we completed a series of experiments investigating the immune-altering effects of surgery severity, time of maximal immune alterations, and recovery, as well as the involvement of beta-adrenergic receptors in surgery-induced immune alterations in Lewis rats. Immune alterations included natural killer (NK) cell cytotoxicity as well as B- and T-cell proliferation. Results showed increased immune suppression with larger incisions (6 cm > 3 cm > anesthesia > saline). In addition, maximal immune alterations induced by surgery occurred after 24 h; anesthesia effects predominated at the earlier time points. Recovery of immune status varied depending on the immunological measure of interest. Although NK cell cytotoxicity returned to control values within 2 days, B-cell proliferation remained suppressed for at least 8 days, and T-cell proliferation did not begin to recover until 4-8 days following the surgical procedure. To assess the mechanisms involved in surgery-induced immune alterations, follow-up assessments evaluated the effect of nadolol, a beta-adrenergic receptor antagonist, on surgery-induced immune alterations. Results show that nadolol blocks the surgery-induced reduction in B- and T-cell proliferation but has no effect on the suppression of NK cell cytotoxicity. These results indicate the need to consider surgical severity and postoperative time of immune assessment when investigating the immune-altering effects of surgery. Importantly, activation of beta-adrenergic receptors appears to play a modulatory role in surgery-induced immune alterations.

Interleukin-6 in the injured patient. Marker of injury or mediator of inflammation?

OBJECTIVE

The effects of interleukin (IL)-6 in the injured patient are examined in an attempt to clarify the potential pathophysiologic role of IL-6 in the response to injury.

SUMMARY BACKGROUND DATA

Interleukin-6 is an integral cytokine mediator of the acute phase response to injury and infection. However, prolonged and excessive elevations of circulating IL-6 levels in patients after trauma, burns, and elective surgery have been associated with complications and mortality. The mechanistic role of IL-6 in mediating these effects is unclear.

METHODS

A review of current literature is performed to summarize the origins, mechanisms of action, and biologic effects of IL-6 and to characterize the IL-6 response to injury.

RESULTS

Interleukin-6 is a multifunctional cytokine expressed by a variety of cells after a multitude of stimuli, under complex regulatory control mechanisms. The IL-6 response to injury is uniquely consistent and related to the magnitude of the insult. Moreover, the early postinjury IL-6 response correlates with complications as well as mortality.

CONCLUSIONS

Interleukin-6 appears to play an active role in the postinjury immune response, making it an attractive therapeutic target in attempts to control hyperinflammatory provoked organ injury.

Blood cytokine levels rise even after minor surgical trauma

The exact changes in cytokine production and clinical implications of the increased cytokine levels following operative trauma remain unclear. In this study, systemic production of a spectrum of cytokines, including IL1 alpha, IL1 beta, IL6, IL8, IL10, and IFN gamma, was examined in patients undergoing minor elective operative trauma. The levels of IL1 receptor antagonist (ra) and IL6 soluble receptor (sR) were also determined. Although there were no changes in IL1 alpha and IL1 beta plasma levels during the entire observation period, there was a significant rise in IL1 ra level in all patients between postoperative day 1 and postoperative day 14. A significant increase in the IL6 plasma level was seen on days 1, 3, and 7 after surgery and an increase in the IL6 sR level was observed on postoperative days 10 and 14. Interestingly, the IL8 plasma values had risen significantly on days 1 and 3 following the operation. In some patients, an elevation in IL10 plasma level was noted on days 1 and 3 postsurgery. Results demonstrated that even a minor surgical procedure such as cholecystectomy with uneventful wound healing was followed by an appearance in the blood circulation of significant levels of cytokines between day 1 and day 14 after surgery. These observations point to the necessity of searching for methods of down-regulating the systemic cytokine effects after surgical trauma for the routine postoperative management.

A suppressive protein generated in peripheral lymph tissue induced by restraint stress

The results discussed here indicate that under the conditions of restraint stress and under the control of CNS, a suppressive protein (NIP) was generated in peripheral lymph tissue and released into the blood stream, which acts as a immune suppressor. It is potentially a very important molecule that could be very important to our understanding of the interaction between CNS and immune function.

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.

Operative stress potentiates the inductivity of membrane associated lymphotoxin (mLT) on lymphokine activated killer (LAK) cells in vitro

Membrane-associated lymphotoxin (mLT) is induced in human peripheral blood mononuclear cells when cultured with interleukin 2, in the form of lymphokine-activated killer (LAK) cells. The inductivity of mLT is thought to be dependent upon the differentiation potential of LAK cell precursors, being T cells and natural killer cells. In this study, we investigated the inductivity of mLT on LAK cells from surgical patients. The preoperative values of mLT inductivity were found to be generally higher in malignant than benign cases, and the postoperative time course of mLT inductivity showed a transient decrease immediately after the operation followed by gradual increase over 2 weeks. Moreover, patients with an intraoperative bleeding volume of more than 1,000 ml showed a delay in the postoperative increase of mLT inductivity. These data suggest that operative stress potentiates the inductivity of mLT on LAK cells; however, excess stress may cause a delay in the restoration of mLT inductivity.

Cell-mediated immunity in severely head-injured patients: the role of suppressor lymphocytes and serum factors

Severe head injury results in suppression of cellular immunity associated with defective in vitro functioning of effector lymphocytes, such as helper T cells and cytotoxic T cells. It is not known whether this suppression in effector lymphocyte function is due to intrinsic lymphocyte dysfunction, to suppressor peripheral blood mononuclear cells (PBMC's) such as suppressor lymphocytes or suppressor monocytes, or to serum factors capable of inhibiting effector lymphocyte function. The purpose of this study was to determine whether a subpopulation of PBMC's and/or serum factor(s) are responsible for this observed suppression in cell-mediated immunity. Cell-mediated immune activity was determined measuring in vitro lymphokine-activated killer (LAK) cytotoxicity following incubation of PBMC's from 15 head-injured patients with those from 15 heterologous normal subjects. The PBMC's were separated into lymphocyte-enriched and monocyte-enriched subpopulations by plastic adherence techniques, and the effect of each population on LAK cytotoxicity was determined. Additionally, the effect on cytotoxicity of serum from the head-injured patients was determined in a dose-response fashion. There was significant depression in LAK cytotoxicity when: 1) PBMC's from normal subjects were incubated with PBMC's from head-injured patients (p < 0.001); 2) lymphocytes (PBMC's depleted of monocytes) from head-injured patients were incubated with PBMC's from normal subjects (p < 0.001); and 3) PBMC's from normal subjects were incubated with serum from head-injured patients (p < 0.001). No suppression in cellular immunity was noted when lymphocytes from normal subjects were incubated with monocytes from head-injured patients. The results indicate that lymphocytes rather than monocytes actively inhibit cellular immunity following severe head injury. The detection of immunosuppressive serum factors suggests a mechanism by which lymphocytes might be modulated by severe head injury.

Serum factor(s) induced by restraint stress in mice and rats suppresses lymphocyte proliferation

LACA mice were individually restrained in a specially made cylindrical cage for 10-20 h at room temperature (20 degrees C). Serum obtained from stressed mice was found to suppress normal mouse lymphocyte proliferation induced by concanavalin A, suggesting the presence of a suppressive factor(s) in the stressed serum. Adrenalectomy or injections of naltrexone (1, 10, or 20 mg/kg, ip), just prior to and in the middle of the stress period, did not affect the suppressive activity of serum from mice. However, the suppressive activity was totally abolished by general anesthesia with urethane (1.5 g/kg, ip). These results suggest that adrenal hormones and opiate receptors are not involved in the generation of the suppressive factor(s) and that the central nervous system plays a very important role in this process. SD rats were restrained in a supine position for 20 h at room temperature (20 degrees C) and serum from stressed rats was also found to be able to suppress normal mouse lymphocyte proliferation. A further analysis of "stressed serum" indicated that the suppressive factor(s) was heat stable (56 degrees C, 30 min) and acid stable (pH 3.8), but sensitive to 100 degrees C (3 min), an organic solvent (greater than 60% methanol), and proteinases (trypsin and chymotrypsin). From the measurement of gel filtration (HPLC), the molecular weights of the suppressive factor(s) were 155 and 370 kDa. Taken together, these results indicate that the suppressive factor(s) is a protein with a large molecular weight.

Evaluation of prostaglandin E1 for prevention of respiratory failure in high risk trauma patients: a prospective clinical trial and correlation with plasma suppressive factors for neutrophil activation

A group of 48 critically injured patients were entered into a prospective, double-blind, placebo-controlled trial to evaluate the efficacy of early infusion of PGE1 for reducing the incidence of severe respiratory failure and mortality. Secondary assessments examined the effects of the PGE1 infusion on plasma mediated suppression of PMN superoxide production and loss of PMN granule enzyme content. The incidence of severe respiratory failure was lower in the PGE1 group--13% versus 32%, but this did not reach significance. The overall morality was equivalent between the two groups--26% (PGE1) versus 28% (placebo). The suppressive activity of the patient plasma was assayed by measurement of normal PMN superoxide production relative to normal control plasma (ratio P:C). The baseline ratio P:C was 62 +/- 5% in the PGE1 group versus 60 +/- 5% in the placebo group. The day 1 plasma samples showed significant reversal of plasma suppressive activity in the PGE1 group--ratio P:C 88 +/- 5% versus 67 +/- 5% in the placebo group (P less than 0.02). In patients who received the full 7 days of infusion, the plasma suppressive activity remained significantly diminished in the PGE1 group--ratio P:C 77 +/- 4% versus 61 +/- 5% (P less than 0.04). The baseline lysozyme content of patient PMN's relative to that of normal control PMNs (ratio P:C) was 119 +/- 14% in the PGE1 group. A significant loss of lysozyme content was observed in the PGE1 group on day 1 of the infusion--ratio P:C 79 +/- 8% (P less than 0.03), and was associated with a reduction in the plasma suppressive activity.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Influence of burn-induced lipid-protein complex on IL1 secretion by PBMC in vitro

The lipid-protein complex (LPC) formed by thermal injury to skin, which has been shown to have a toxic effect on mice, and which suppresses the immune response, was tested for its specific influence on monocytes. Growth of bacterial endotoxin-stimulated peripheral blood mononuclear cells (PBMC) was inhibited in the presence of LPC, however, the inhibition was less at the time of the optimal rate of cell proliferation. Inhibition was proportional to LPC concentration. ConA-stimulated PBMC were also inhibited by LPC in a dose-related manner. PBMC, in the presence of LPC, secreted interleukin 1 (IL1) at an increasing rate as LPC concentration rose from 5 to 40 micrograms/ml, and the levels of IL1 which could be induced by endotoxin were increasingly amplified in the presence of LPC. In comparison to LPC, the native tissue proteins which were isolated from unburned skin by the same techniques which produced LPC from burned skin, were tested for their effect on PBMC. Native proteins had no effect on IL1 secretion, whether on background or endotoxin-stimulated levels. Thus, the thermally induced change in skin proteins has a specific effect on monocyte IL1 secretion which is not matched by the native proteins, indicating that burn injury to skin specifically affects the lymphokine cascade and consequent immune function.

Immunosuppression in Trauma Patients

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

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.

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.

Humoral immunodeficiency syndrome in patients with severe head injury?

Twenty patients with severe head injury were analysed as to whether they developed a humoral immunodeficiency syndrome. In spite of the fact that 75% developed pyogenic complications all patients showed a polyclonal humoral activation of their immune system with an increase in IgG, IgA, IgM and the complement factors. Four patients died from cerebral complications partly associated with infections. Because our patients did not develop a humoral immune defect and because there is no proof so far of a cellular defect, we think that the cause of respiratory infections is a pulmonary disturbance primarily caused by hypothalamic factors, whose release is stimulated by traumatically induced cerebral lesions.

Spontaneous lymphocyte proliferation during trauma and infection

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

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 pattern of leucocyte response to surgical trauma in the African Negro

The leucocyte response to surgical trauma in the Nigerian Negro is investigated. The surgical operations were graded, according to the degree of anticipated tissue trauma, into minor, intermediate and major, in 66 patients (27 males and 39 females) who had elective surgical operations with no sign of infection. The peripheral blood total and differential leucocyte counts were determined pre-operatively and at 2 h, 24 h, and 7 days postoperatively. A highly significant increase (P less than 0.001) in the total leucocyte, polymorphonuclear leucocyte (PMN) and stab cell counts occurred 2 h and 24 h after major surgery. These changes persisted for 7 days after major surgery except for the stab cell count which was by then no longer significantly raised. Similarly, highly significant increases occurred in the total and PMN counts 2 h and 24 h after intermediate surgery. The increases were not significant by the 7th postoperative day. There was a decrease in the lymphocyte counts after major surgery which was not significant at 2 h but was just significant (P less than 0.05) 24 h postoperatively. There was a return to the pre-operative level by the 7th postoperative day. There were no significant changes in the leucocyte counts after minor surgery or in the monocyte, eosinophil and basophil counts after intermediate or major surgery. Despite lower pre-operative total leucocyte (WBC) and PMN counts found in this study, the total leucocyte and PMN response to surgical trauma in the Nigerian Negro is similar to previous observations made in the Caucasian. The response of lymphocytes in the Nigerian Negro, however, differs from that reported in the Caucasian and demands further study.

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.

Endorphinergic modulation of immune function: potent action of the dipeptide glycyl-L-glutamine

Glycyl-L-glutamine (GLG), the carboxy terminal dipeptide of B-endorphin, inhibits brainstem neuronal activity. It also occurs along with B-endorphin in pituitary secretory vesicles suggesting a neurosecretory role for this dipeptide. We have evaluated potential immunoregulatory actions of this compound using the Phytohemaglutinin (PHA) blastogenesis and the concanavalin A (ConA) suppressor cell induction assays. GLG in low doses (10(-12) M) enhanced the response of human lymphocytes to PHA induced blastogenesis, however; with higher doses of the dipeptide (10(-7) M) immunosuppression was consistently observed. In the suppressor cell induction assay, when GLG was used together with ConA, we observed a dose-dependent inhibition of suppressor activity. These results clearly indicate that GLG produces a dose dependent bidirectional modulation of at least two indicies of immune function, and confirm the presence of a second pituitary peptide with the potential for potent immunomodulatory action.

Abrogation of the tumor promoting effect of allogeneic blood transfusion by polyadenylic-polyuridylic acid (poly A-poly U)

Studies from several centers have shown an immunosuppressive effect of surgical procedures, whilst others have shown blood transfusion in association with cancer surgery to have an adverse effect on ultimate prognosis. We have previously demonstrated enhanced growth of tumor metastases, in rats following allogeneic blood transfusion and surgery. Polyadenylic-polyuridylic acid (poly A-poly U) has been reported to stimulate immune responses. In this report, we have investigated the effectiveness of poly A-poly U as an adjuvant to blood transfusion and surgical procedures in BN rats bearing artificial lung metastases. Significantly reduced tumor growth was observed, following poly A-poly U adjuvant treatment. These results lead to serious contemplation of the use of this drug as adjuvant therapy in blood transfused and surgically treated patients.

Immunity of the burned patient. An overview

The study of mortality in severe burns shows very clearly that most patients die because of septic problems. Surgery and intensive care in burn patients are actually well established, but the fight against infection and septicemia is still difficult. The risk arises due to poor host defence, leading to an unfair struggle and very often ending in death. Today it has become necessary for every burn surgeon and plastic surgeon to understand why this immune depression occurs and how it can be prevented or treated.

Appearance of spontaneously Ig secreting B cells in human peripheral blood after surgery

Lymphoblastoid B cells, spontaneously secreting specific antibodies of IgG and IgA classes, are constantly detected after in-vivo immunization and represent a sensitive marker of a recent antigenic exposure. In this study we demonstrate that surgical trauma is followed, at a well-defined time after surgery, by the appearance of circulating lymphoblastoid B cells spontaneously secreting IgG and IgA. The kinetics and the functional behaviour of this B cell subset are identical to those of lymphoblastoid B cells observed after in-vivo immunization. Our data indicate that surgical trauma activates a humoral immune response. Antigens released by traumatized tissues or encountered through breaches in skin or mucous membranes might initiate the reaction.

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.

Effect of beta-endorphin and cortisol on the PHA stimulated lymphoblastogenesis

The mechanism of immune suppression in a severely stressful condition is not known. Since the demonstration of β-endorphin receptor on the surface of the circulating lymphocyte, it was reported that β-endorphin could suppress PHA stimulated lymphoblastogenesis. Because the concentration of β-endorphin was supraphysiologically high, it is doubtful that β-endorphin can suppress the lymphoblastogenesis directly in vivo. We investigated the suppression of PHA stimulated lymphoblastogenesis by β-endorphin in vitro and the effect of β-endorphin in some conditions where β-endorphin increases in vivo. PHA induced lymphoblastogenesis of T lymphocyte was maximal at the concentration of 5 μg/ml. β-endorphin could not suppress the blastogenesis even at the highest concentration. In the five healthy men who received metyrapone the previous night, PHA stimulated blastogeneses were not significantly suppressed. In a patient with Nelson’s syndrome, the lymphoblastogenesis was suppressed at all concentrations of PHA. Cortisol significant suppressed the blastogenesis even at the concentration of 10 μg/dl and its suppressive effect was shown in dose dependant manner. Our results suggested that β-endorphin could not suppress the lymphoblastogenesis directly in vivo.

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.

Inadequate interleukin 2 production. A fundamental immunological deficiency in patients with major burns

We studied the production of the two major mediators of cellular immune responses, Interleukin 1 (IL-1) and Interleukin 2 (IL-2), by the peripheral blood mononuclear cells of 23 burn patients (16 men, seven women, mean age 48.9 years) compared with 23 matched controls (16 men, seven women, mean age 46.7 years). Serial measurements were made of IL-1 production by adherent mononuclear cells after stimulation with lipopolysaccharide and of IL-2 production by lymphocytes after stimulation with phytohemagglutinin (PHA). Eighty determinations of IL-2 production by lymphocytes from 12 patients with greater than 30% body surface area burn revealed a mean IL-2 production of 0.71 u as compared with a mean of 1.23 u for patients with less than 30% burns (p = 0.04). Patients with greater than 30% body surface area burns had significantly reduced IL-2 production (p less than or equal to 0.05) until 60 days after injury, whereas those with smaller burns had reduced IL-2 production only at 20-29 and 30-39 days postburn. Nine burn patients with systemic sepsis showed significantly lower IL-2 production (p = 0.03) at 10-29 days postburn than nonseptic patients, and significantly less IL-2 production during septic episodes. Eight patients with greater than 50% suppression of lymphocyte response to PHA produced less IL-2 (0.4 u) than patients with less than 50% suppression, (1.07 u, p = 0.004). IL-1 production was significantly elevated as compared with controls (4.45 u vs. 3.6 u, p = 0.05) early after injury, but was subsequently within the normal range regardless of burn size. The percentage of circulating helper T-lymphocytes, the principal source of IL-2, was also reduced, although this did not always correlate with IL-2 production, which remained depressed after recovery of the helper T-cell population. These results indicate that failure to produce IL-2, a powerful mediator of cellular immune responses, is an important mechanism underlying the defective cell mediated immunity seen in burn patients.

The significance of changes in blood lymphocyte populations following surgical operations

After surgery blood lymphocyte levels fell to one-third of the pre-operative value. Since this depression was transient, and followed the peak of serum cortisol closely, it was probably due to a redistribution of lymphocytes from the blood to the tissues. The proportion of activated lymphocytes, as measured by the incorporation of 3H-thymidine in vitro without added mitogen, was substantially increased about 5-8 days after operation. The greatest number of S-phase lymphocytes was found after operation combined with blood transfusion but surgery alone and blood transfusion alone each produced significant increases. The proportions of B lymphocytes, T helper cells and T suppressor cells remained nearly constant despite the fluctuations in total lymphocyte counts. The response of lymphocytes in vitro to phytohaemagglutin (PHA) was doubled on average 7 days after surgery provided the test was performed in the patient's own serum. In pooled serum there was no consistent change in the response to PHA. It is argued that none of the observed changes necessarily signify that a phase of immunosuppression follows surgical operations.

Immunologic response of trauma and burns. An overview

Immunologic alterations occur after elective surgery, accidental injuries, and burns. These alterations are dose-related, that is, minor insults bring about minor alterations that appear to be of no clinical relevance, but major accidents and extensive burns cause major alterations, which have been correlated with the incidence of life-threatening septic complications. Because many aspects of the immune system seem to be affected, a concerted move in the direction of immunologic manipulation of the surgically injured patient has been difficult. Nevertheless, several potentially promising avenues of immune modulation are currently undergoing clinical trials.

In vitro leukocyte endogenous mediator production is not impaired following surgical stress in moderately malnourished patients

Leukocyte endogenous mediator (LEM), a protein produced by phagocytizing cells, plays a critical role in the metabolic response to injury and infection. There is an important interaction between protein-calorie malnutrition and the capacity of cells to produce LEM, since severely malnourished or severely stressed individuals, have a reduced capacity to produce LEM. The leukocytes of 10 mildly to moderately malnourished patients undergoing elective major surgery, a moderate stress, had an intact ability to produce LEM on preoperative assessment. This ability was not affected by a 5-day postoperative period of hypocaloric nutrient intake despite a significant loss of body protein in one-half of the patients and a significant fall in serum protein concentrations. These results suggest a high biologic priority for LEM production during the metabolic response to injury and for infection.

[Immune disorders during postoperative peritonitis]

Despite major diagnostic and therapeutic advances, postoperative peritonitis appeared to be still associated with a severe prognosis. The failure to react to delayed hypersensitivity skin tests was recently shown to identify patients at increased risk for sepsis. In an attempt to clarify the mechanisms of this anergy, cellular and humoral immunity was studied with in vitro tests in 12 patients treated for postoperative peritonitis. Complement was decreased in 33.3% of cases and normal in the others. No significant change was found in IgG and IgM titres, but IgA concentrations were increased in 80% of cases. A decrease in the total number of lymphocytes was observed in 41.7% of patients, related to the reduction in the total T lymphocyte count. Mitogen-induced lymphocyte transformation was studied with phytohaemagglutinin, concanavalin A, pokeweed-mitogen, and tuberculin purified protein derivative. Six patients had decreased or negative response to at least three mitogens; 91,7% had no response to tuberculin. The leukocyte migration inhibition test was negative in all cases. These abnormalities in cell mediated immunity may have been related to underlying diseases (severe nutrition depletion in 7 cases), to sepsis (septic shock in 10 cases), to repeated anaesthesias and surgical procedures, and even to drugs (e.g. antibiotics). The presence of serum inhibitors may have been the cause of the anergy and further studies are required.

The role of protease in immunoregulation

Whilst immunodepression is widely recognized in patients subject to trauma or chronic disease, the mechanism of this process is poorly understood. We found that most of the lymphocyte suppressive activity of plasma from severely ill patients was attributable to the protein alpha 2-macroglobulin (alpha 2 M) and low molecular weight peptide (less than 10000). The only major variation in alpha 2 M concentration was found in patients subject to trauma, when it was depressed at times of high plasma suppressive activity. In order to explain qualitative immunosuppressive differences in alpha 2 M we studied its functional role as the main route for binding and degrading proteolytic enzyme (protease). In normal plasma minor degrees of protease complex formation to alpha 2 M caused greatly increased suppressive activity due principally to alpha 2 M and the abnormal appearance of low molecular weight peptide (less than 10000). Study of protease inhibitor function in patients suffering from acute or chronic illness suggested that in these patients their plasma becomes immunosuppressive due to inadequate handling of protease, resulting in alpha 2 M-protease complexes or inhibitory peptides persisting in the circulation. Opportunities for background immunoregulation by altering protease metabolism are considered.

Failure of splenic implants to protect against fatal postsplenectomy infection

Overwhelming postsplenectomy infection is not a phenomenon confined to children. In all age groups, splenic trauma that requires surgery should be managed by splenorrhaphy if possible. Autoimplantation of splenic fragments into omental pockets has been performed in the few patients we have seen who required splenectomy. A case has been presented in which these small implants failed to protect a 61 year old woman from the development of fatal pneumococcal sepsis. The patient had received a pneumococcal vaccination, and her implants had shown activity on radionuclide scanning. Concerns about critical splenic mass, blood supply to the implant, and hepatic function require further study before this technique can be considered efficacious.

Fatal infection in mice after injection of immunosuppressive serum fractions from surgical patients

Following surgical or accidental trauma many patients show suppression of cellular immunity. In this investigation sera from severely burned patients and patients undergoing aortic aneurysm repair were studied. Sera shown to suppress phytohaemagglutinin-induced blastogenesis of normal human lymphocytes were fractionated using ion exchange and G25 Sephadex chromatography. Suppressive activity was largely confined to a low molecular weight (LMW) fraction and was dose dependent. LMW fractions of normal sera had no significant suppressive activity. The purpose of this study was to test the causal relationship between immunosuppressive serum and decreased resistance to bacterial infection. Listeria monocytogenes infected mice were used as an in vivo model to test suppression of cellular immunity. Injection of LMW fractions of suppressive sera significantly increased mortality in these mice, but had no effect on non-infected mice. There was good correlation between the in vitro and in vivo effects of the suppressive fractions. These results suggest that a circulating factor in the serum of injured patients suppresses cellular immunity and may be responsible for impaired resistance to infection.

Fluid and mononuclear cells from healing wounds inhibit thymocyte immune responsiveness

It has been shown previously that fluid obtained from 7-day-old wounds noncytotoxically inhibits normal thymic lymphocyte blastogenesis and that mononuclear cells (MNC) from the same wounds lack mitogenic responsiveness. The present series of experiments studies whether wound MNC are the source of the wound inhibitory factor(s) and the effect of adult thymectomy (ATDX) on their generation. Adult male Sprague-Dawley rats (300-350 g), intact or ATDX (performed at 8-10 weeks of age), underwent dorsal wounding (7 cm) and subcutaneous implantation of sterile Ivalon sponges. Seven days later sponges were harvested, wound fluid was obtained, and the cell pellet was purified to 90% MNC. Normal rat thymocyte blastogenesis (stimulation index) to Con A and PHA evaluated in a microculture system (10 separate experiments) was 169.9 +/- 10.0 and 30.1 +/- 3.7. Addition of 10% wound fluid markedly inhibited thymocyte mitogenesis--6.3 +/- 1.0 and 2.7 +/- 0.6, respectively (P less than 0.001). Heat-inactivated wound fluid (56 degrees C, 30 min) had similar inhibitory activity--3.4 +/- 0.9 and 2.7 +/- 0.6 (P less than 0.001). Normal thymic blastogenesis could also be inhibited by the addition of 5 X 10(4) wound MNC to the microculture system--4.4 +/- 1.1 and 1.9 +/- 0.3 (P less than 0.001). Wound fluid from ATDX rats had much less inhibitory activity (77.1 +/- 22.4 and 7.2 +/- 2.1, P less than 0.01) vs control wound fluid. In addition wound MNC from ADTX animals were also less immune suppressive (30.7 +/- 4.9 and 13.5 +/- 3.7, P less than 0.001) than control MNC. Forty-eight-hour supernatants of wound MNC from intact rats, added in 25% concentration to normal thymocyte cultures, demonstrated inhibition similar to that of the wound fluid from the same animals: 4.4 +/- 0.7 and 3.9 +/- 0.6, while ATDX MNC supernatants had minimal inhibitory activity (110.1 +/- 18.2 and 25.7 +/- 6.5, P less than 0.005). No cytotoxicity could be demonstrated in any of these experiments by trypan blue exclusion. It is concluded that 7-day-old wound fluid noncytotoxically inhibits thymocyte blastogenesis; this effect is also demonstrated by wound MNC and their supernatants, suggesting immune "suppressor" lymphocytes are present in wounds; ATDX, which abrogates suppressor cell induction, leads to marked diminution of wound inhibitory activity. The data suggest that important immune events occur at the wound site; their relation to normal wound healing remains to be elucidated.

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.

Beta-endorphin modulates human immune activity via non-opiate receptor mechanisms

Here we report that Beta-endorphin is a potent and efficacious suppressor of phytohemagglutinin induced T-lymphocyte blastogenesis when human leukocytes are exposed early in the course of mitogenic activation. This suppression becomes more difficult to observe, however, if blastogenesis is established by prior exposure to mitogen. Suppression by Beta-endorphin is not blocked by pretreatment with the opiate antagonist naloxone. These results, therefore, suggest that neuroendocrine modulation of human immune expression may be a peripheral physiological function of Beta-endorphin which is mediated by mechanisms distinct from traditional opiate receptors.

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.