Identification of material with paternal HLA antigen immunoreactivity from purported circulating immune complexes in patients with gestational trophoblastic neoplasia.

Circulating immune complex(es) (CIC) have been shown to rise progressively only when patients with hydatidiform molar pregnancy enter gonadotropin-documented remission. The CIC in 3 patients with gestational trophoblastic neoplasia (GTN)--1 with hydatidiform mole and 2 with choriocarcinoma--were characterized. Their clinical course was monitored by serial antigen-nonspecific polyethylene glycol (PEG) 6000-CIC assay and simultaneous human chorionic gonadotropin (HCG) assay from presentation until sustained gonadotropin-documented remission. As serial HCG progressively decreased to normal following surgical or chemotherapeutic reduction in tumor burden, PEG-CIC concurrently rose. Serum obtained at or near peak PEG-CIC levels was precipitated by 3.75% PEG 6000 and fractionated by column chromatography on Sephadex G-200 (exclusion limit, greater than 600,000 mol wt) in glycine-HCl and 1 M NaCl buffer at pH 2.8. None of the 5 elution fractions obtained from the 3 patients contained HCG or anti-HCG activity. However, in the hydatidiform molar patient, fractions 1 through 3 (mol wt greater than 67,000--and containing immunoglobulin) were shown to competitively inhibit complement-dependent antibody lysis on 1 of 4 paternal HLA haplotype (AW32) targets. In 2 of the 3 patients studied, low-molecular-weight fractions (not containing immunoglobulin) significantly inhibited reference anti-HLA binding of antisera directed against only 1 of 4 paternal HLA haplotypes. The immunospecificity of this inhibition was confirmed by criss-cross control assays in which elution fractions obtained from both of these patients were tested for inhibition of lymphocytolysis of both sets of paternal lymphocytes. None of these fractions were immunoreactive to maternal HLA haplotypes. Further analysis of serum from the hydatidiform molar patient revealed that no free complement-fixing antibody against paternal antigens could be found by conventional screening assays in unfractionated patient sera. Three of 4 paternal HLA antigens or non-complement-fixing anti-HLA immunoglobulin was detected in unfractionated pretreatment, treatment, and remission sera of the hydatidiform molar patient. Only in this patient's remission sera was unbound AW32 antigen or non-complement-fixing anti-AW32 antibody detected. These data demonstrate the successful characterization of at least 1 specific antigen fractionated from a tumor-associated immune complex. The implication that some patients with GTN may recognize and react to immunogenic paternal HLA antigens as part of their successful response to therapy for trophoblastic tumor is discussed.

Circulating immune complex levels in patients with gestational trophoblastic neoplasia.

The clinical course, human chorionic gonadotropin (HCG) levels, and serial circulating immune complex (CIC) levels in 21 patients with gestational trophoblastic neoplasia (GTN) were correlated for the evaluation of the relationship between CIC levels and trophoblastic tumor burden. CIC levels were normal in 18 of 21 patients at the time of presentation, and 2 of 3 patients who presented with elevated CIC levels had significant comorbid disease (toxemia and hepatitis). Nine patients were followed into gonadotropin remission, and all 9 developed an increase in CIC levels at the time of remission. It was concluded that CIC, at least as measured by two antigen-nonspecific techniques, is generally not elevated at initial presentation in the patient with GTN; this lack of an elevation is probably due to marked tumor antigen excess. Thus the in vivo importance of CIC as a "blocker" of host antitumor response at this stage is doubtful. After effective treatment as HCG levels return to normal, the demonstrated elevation in serial levels of CIC may reflect a return of adequate host immune response at a time of minimal tumor burden.

Serial circulating immune complex levels and mitogen responses during progressive tumor growth in WF rats.

Inbred male WF rats were given im injections of one of two antigenically and histologically distinct syngeneic tumor isografts, adenocarcinoma DMH-W 163 or spontaneous renal cell carcinoma SPK. Serum and peripheral blood lymphocytes were harvested from tumor-bearing and normal age-matched controls before and after isograft challenge at weekly intervals. Serial circulating immune complex (CIC) levels were quantitated by polyethylene glycol (PEG) insolubilization. T-cell mitogen responses to phytohemagglutinin (PHA) and concanavalin A (Con A) were followed serially. Tumor growth was measured at least weekly. PEG-CIC values rose early after tumor injection, increased with tumor growth, and declined in some animals just before death. Mitogen response to PHA was significantly decreased in isografted tumor-bearing rats, particularly at later stages of tumor development, compared to normal uninoculated controls. Responses to Con A were variable, and suppression was not always seen in tumor bearers. In animals that did not have progressive tumor growth after isograft injection, PEG-CIC levels did not change and responses to PHA were not suppressed. Patterns of CIC change and responses to PHA were not affected by differences in tumor histology or growth rates. Thus serial CIC levels measured by the PEG assay correlate with tumor growth and precede nonspecific suppression of T-cell mitogenic response in these animal tumor models.

Modification of in vitro and in vivo immune function by acute inflammatory cells.

The ability of adoptively transferred, syngeneic polymorphonuclear leukocyte-rich (PMNLr) inflammatory cells to influence lymphocyte-mediated cytotoxicity (LMC), complement-dependent cytotoxicity (CDC), and skin allograft survival was studied in a murine model. BALB/c mouse PMNLr, stimulated by i.p. injection of either glycogen (G/PMNLr) or thioglycollate (T/PMNLr), were transferred to other BALB/c mice at the time of primary or secondary immunization with a cellular alloantigen (C57BL/6 spleen cells) or after skin allografting (C57BL/6 tailskin). The metabolic activity of each PMNLr population was determined by measuring glucose utilization in the hexose monophosphate shunt. It appeared that metabolic activity of the T/PMNLr was significantly greater than that of the G/PMNLr. Our results indicate that, while the infusion of G/PMNLr tended to suppress the primary cell-mediated immune response and the secondary humoral immune response, the infusion of T/PMNLr stimulated both of these responses. Furthermore, i.p. infusion of mice with G/PMNLr at a time approximating grafting resulted in prolonged graft survival, but neither T/PMNLr nor syngeneic thymocytes effect graft survival. Our data demonstrate that both cellular and humoral immunity can be modified by acute inflammatory cells. The metabolic status of the acute inflammatory cells seems to be critical in determining their immunoregulatory potential.

The effects of injury on the adaptive immune response.

For more than thirty years it has been apparent that serious injury in humans and experimental animals is associated with a decrease in immune functions dependent upon T cells, the principal cells involved in initiating adaptive immune responses. This review focuses on more recent evidence that T helper cell function is altered after serious injury with loss of T helper 1 function and cytokine production and with preservation of T helper 2 function and an increased production of T helper 2 cytokines. Emphasis is placed on the importance of interactions between the innate and adaptive immune systems in the perturbed immune responses seen following injury. Immunomodulatory strategies are mentioned that have had success in animal models in ameliorating the diminished resistance to infection commonly seen after major traumatic or thermal injury. Finally, it is emphasized that immunomodulatory treatments that are successful in preventing infection may be contraindicated once infection is manifest.

Hepatic failure and coma after liver resection is reversed by manipulation of gut contents: the role of endotoxin.

Despite significant improvements in the surgical care of patients, hepatic failure after extensive liver resection continues to be associated with a high morbidity and death. We postulated that hepatic failure after liver resection was related to gut-derived endotoxemia. Rats were randomized to receive oral gavage twice daily with one of the following preparations: (1) 0.9% saline; (2) neomycin sulfate and cefazolin; (3) cholestyramine; (4) lactulose. After 7 days of gavage, animals underwent either a two-thirds partial hepatectomy or sham operation. At time 0 (preresection), 10, 20, and 30 hours after resection, aortic blood was obtained for determination of ammonia, glutamine, and endotoxin levels. In selected animals, portal vein or inferior caval blood was obtained simultaneously with the aortic sample to evaluate the glutamine and ammonia exchange across the intestine and hind limb. Germ-free rats also underwent a partial hepatectomy or sham operation, and blood was obtained for glutamine and ammonia exchange at 0 and 20 hours after resection. Hepatectomy in the saline-pretreated rats resulted in a sixfold increase in plasma glutamine, increased uptake of glutamine and release of ammonia by the gut, increased release of glutamine by the hind-limb, and a high mortality rate. Pretreatment with agents that altered gut contents reduced the endotoxemia, maintained normal glutamine and ammonia levels, and reduced the mortality rate. Germ-free rats had a similar response to that seen in treated animals. Altering the gut contents in this model reduced the level of endotoxemia, blunted the catabolic response, and enhanced survival.

Neutrophil activation after burn injury: contributions of the classic complement pathway and of endotoxin.

We attempt to elucidate the mechanisms of neutrophil (PMN) activation after burn injury. We previously reported prolonged elevations of PMN cell surface complement (C) opsonin receptor levels after burn trauma with a corresponding period of depressed PMN chemotaxis to C5a, which suggests that the C product, C5a, was responsible for PMN activation. However, a lack of direct correlation of C activation with C receptor levels soon after injury raised the possibility of a second PMN-activating substance. We therefore investigated the effect of endotoxin (LPS) on the expression of the C receptors (CR1 and CR3) by normal human PMNs. Concentrations from 0 to 50 ng/ml of LPS 026:B6 caused a dose response increase in the PMN surface expression of CR1 and CR3 as assessed by monoclonal antibody binding and indirect immunofluorescence. The relative CR1-dependent fluorescence rose from a mean of 50 to 385 and CR3 from 50 to 300. Chelation by ethylenediaminetetra acetic acid (EDTA) did not influence this dose response, thus ruling out the possibility of C activation by LPS--an inference supported by the lack of complement activation observed with these concentrations of LPS in normal serum. A similar dose response was obtained in the absence of other cell types or serum, which implies a direct effect that mimicked that of C5a. To determine the mechanism of the later, prolonged C activation after burn injury, we next examined C activation products in 22 patients with burn injuries. Elevations of plasma C3a desArg were present and persisted for 50 days. Elevations were at maximum levels on days 9 through 13 postburn (mean +/- standard error of mean [SEM], 496 +/- 47 ng/ml versus normal 113 +/- 32; p less than 0.01). These were accompanied by elevations of C4a desArg (917 +/- 154 ng/ml versus normal 424 +/- 50; p less than 0.01), which are indicative of classic pathway activation. Finally, we examined PMN function, phagocytosis and percentage killing of Staphylococcus aureus, and found PMN function to be unaltered in the 22 patients. Thus PMN activation after burn injury appears to be caused by LPS soon after injury and by C5a later after injury and affects only selected PMN functions.

A single dose of endotoxin activates neutrophils without activating complement.

Both complement (C) and neutrophils (PMN) are activated in critically ill patients. To evaluate the role of endotoxin in this response, we studied C activation products and PMN cell surface receptors in seven normal subjects before and after endotoxin (USRef 20 U/kg) or saline solution administered on separate occasions. By 4 hours, with endotoxin only, all subjects had myalgia, headache, an increase in body temperature and heart rate, and leukocytosis that returned to normal by 24 hours. At the same time, PMN cell surface receptors for the complement opsonin C3b increased, as measured by indirect immunofluorescence, rising to 251 +/- 44% of baseline by 4 hours (p less than 0.01) and remaining elevated at 24 hours (237 +/- 16%, p less than 0.01). PMN receptors for iC3b increased to 308 +/- 49% of baseline by 4 hours (p less than 0.02) and returned to normal by 24 hours. There was no change in plasma of C3a desArg, C4a desArg, and C5a desArg (4 hours: mean C3a: 153.4 +/- 11.5 ng/ml versus 176.2 +/- 16.2 ng/ml for saline solution, p = ns; C4a: 159.6 +/- 32 ng/ml versus 151.4 +/- 21 ng/ml, p = ns; C5a: undetectable). To confirm the lack of C activation, we examined PMN chemotaxis (CTX) to C5a for any impairment caused by prior in vivo exposure to C5a. CTX to C5a was unaffected (4 hours: 109% +/- 22% of normal versus 114% +/- 10% for saline solution, p = ns). PMN CTX to formyl-methionyl-leucine-phenylalanine and PMN phagocytosis and killing of S. aureus were also unaffected by endotoxin. Thus, a single dose of endotoxin produced a subjective febrile illness and precipitated sustained PMN activation as indicated by increased PMN cell surface complement receptor number in the absence of C activation.

Recombinant interleukin-2 (rIL-2) improves immune response and host resistance to septic challenge in thermally injured mice.

Impaired immune competence leading to decreased resistance to sepsis is a major cause of death in burn patients. We have previously shown that increased mortality from a septic challenge correlated with impaired splenocyte interleukin-2 (IL-2) production and response to T cell mitogens in mice subjected to a 25% surface area scald burn. We report now that the addition of recombinant (r) IL-2 (100 U/ml) in vitro to splenocytes from burned animals restored mitogen responses to normal. Burned mice intraperitoneally received 16,000 U of rIL-2 (selected on the basis of dose-response experiments) once daily in 0.5 ml 5% dextrose (5% D) on days 1 through 6 after thermal injury and were compared with burned mice treated with only 5% D. Both groups were subjected to cecal ligation and puncture 10 days after burn; 4 days later, there were no survivors in the 5% D group, whereas 45% of the rIL-2 group remained alive (p = 0.001; Gehan statistic). We found that rIL-2 treatment at the dose selected resulted in no apparent toxicity in burned mice. Finally, splenocytes from rIL-2-treated burned mice showed improved responses to T cell mitogens in vitro compared with 5% D-treated controls. We conclude that rIL-2 therapy may have a role in the restoration of immune competence after thermal injury.

Temporal correlation of impaired immune response after thermal injury with susceptibility to infection in a murine model.

Suppression of cellular immunity and increased susceptibility to sepsis frequently accompany thermal injury. However, a convincing association between the two has been difficult to establish in human beings. Therefore we chose to investigate the relationship of impaired cell-mediated immunity with susceptibility to sepsis in an animal model. We studied the response to phytohemagglutinin (PHA) and interleukin-2 (IL-2) production by splenocytes from mice subjected to a standard 25% scald burn and killed at intervals of 3, 5, 7, 10, 14, and 25 days after thermal injury. Burned mice were compared in all instances to sham-burn animals (i.e., animals that had been anesthetized and shaved but not burned). We also studied mortality after cecal ligation and puncture (CLP), as a septic challenge, in burned and control animals at the same postburn intervals. We found maximal suppression (50% to 55%) of the PHA response at 10 to 14 days after injury and maximum suppression (68%) of IL-2 production at 7 days. Both of these parameters returned to normal by postinjury day 28. Mortality after CLP increased gradually from control levels after thermal injury up to a maximum of 88% on postburn day 10 and also returned to control levels after 28 days after burn. Significant correlations were found between mortality after CLP in the postburn period and suppression of the PHA response, on the one hand, and the suppression of IL-2 production, on the other (r = 0.89 and 0.91, respectively; p less than 0.05). This result implies a causal relationship between impaired cell-mediated immunity and susceptibility to sepsis after burn injury.

Interleukin-12 treatment restores normal resistance to bacterial challenge after burn injury.

BACKGROUND: Preliminary studies in this laboratory have shown that treatment with interleukin-12 (IL-12), a cytokine that induces expression of the T-helper-1 lymphocyte phenotype, in an animal model of burn injury increased survival after a septic challenge. The purpose of this study was to define the efficacy of IL-12 therapy and to explore its mechanism of action. METHODS: Adult male A/J mice were subjected to 25% full-thickness scald or sham burn. Starting on day 3 after burn, groups of mice received five daily injections of IL-12, interferon-gamma (IFN-gamma), or saline solution. Some animals received anti-IFN-gamma monoclonal antibody. At day 10 most animals underwent cecal ligation and puncture (CLP) and were observed for survival. Some animals were killed at day 10, and CD4-enriched splenocytes were stimulated with anti-CD3 antibody or concanavalin A and were studied for cytokine production and mRNA expression. RESULTS: IL-12 treatment, 25 ng daily for 5 days, increased survival of the burn group after CLP to that of the sham burn control group. Anti-IFN-gamma antibody, 500 micrograms, administered 1 day before IL-12 treatment, reduced the efficacy of IL-12. IFN-gamma treatment, 7000 units, moderately increased survival. IL-12 had no effect on survival of the sham burn group. At the time of CLP IL-12 therapy had induced a marked decrease in CD4+ lymphocyte IL-4 and a moderate increase in IFN-gamma production and mRNA expression without affecting IL-2. CONCLUSIONS: IL-12 is the most effective therapy so far tested in this burn plus CLP model. It acts at least in part through IFN-gamma. However, IFN-gamma therapy was not as effective as IL-12.

The humoral immune response after thermal injury: an experimental model.

BACKGROUND: Severe thermal injury is associated with major alterations in cell-mediated immunity. Because most B-cell responses are regulated or critically dependent on T-cell help, it is not surprising that many studies have also shown a variety of defects in humoral immunity after thermal injury. However, the nature of the relationship between the in vitro ability to produce antibody and subsequent in vivo responses remains unclear. METHODS: With a murine model of thermal injury, the primary and secondary humoral immune response to tetanus toxoid (TT) was examined during a 6-week period after sham burn or burn injury. Serum anti-TT titers and the numbers of anti-TT-secreting splenocytes were determined. RESULTS: Splenocytes from burned animals displayed normal or decreased TT-specific immunoglobulin (Ig) M plaque formation. In contrast, however, IgG plaque formation was persistently increased for up to 6 weeks after thermal injury, suggesting a switch from IgM to IgG antibody production. Conversely serum titers of TT-specific IgG antibody were persistently lower in burn, compared with sham groups. Changes in serum immunoglobulin levels did not account for this marked discrepancy between enhanced in vitro IgG plaque formation but impaired in vivo levels of TT antibody. CONCLUSIONS: The data suggest that thermal injury is associated with a diminished ability to propagate and maintain a normal IgG antibody response, despite the presence of normal or increased numbers of antigen-specific B cells.

Molecular mechanisms of decreased interleukin-2 production after thermal injury.

BACKGROUND: Among the fundamental immunologic abnormalities induced by serious traumatic or thermal injury are alterations in T cell activation, reduced lymphocyte interleukin-2 (IL-2) production, and associated depression of T lymphocyte proliferation. This study attempts to localize the cellular mechanisms underlying abnormal IL-2 production in thermal injury. METHODS: Following National Institutes of Health guidelines, 150 A/J mice were anesthetized, subjected to a 20% full-thickness scald burn injury or sham burn, and killed at intervals from 4 to 21 days later; splenocytes were harvested for in vitro studies. For measurement of IL-2 production, cells were cultured with either concanavalin A or a combination of the phorbol ester PMA, which directly activates protein kinase C, and the calcium ionophore A23187, which increases intracellular calcium. Cytokine mRNA expression was measured by Northern blot analysis and IL-2 production by bioassay. RESULTS: Both IL-2 production and IL-2 mRNA expression were consistently suppressed in concanavalin A-stimulated cells from burned mice compared with sham burns. This suppression of IL-2 and IL-2 mRNA also occurred when T cells were activated with PMA and A23187, bypassing the earlier stages of the signal transduction mechanism. IL-1 beta and tumor necrosis factor-alpha mRNA expression were consistently increased in burned animals, indicating that decreased IL-2 mRNA expression was specific to IL-2 and not representative of a global decrease in cytokine mRNA expression. CONCLUSIONS: These results suggest that the principal cellular abnormalities that result in altered T cell activation and IL-2 production after thermal injury lie downstream of the initiating signal transduction events and before IL-2 gene transcription.

Circulating immune complex levels in patients with molar pregnancy.

Circulating immune complex levels were measured in patients with molar pregnancy to investigate the relationship between circulating immune complex and trophoblastic tumor burden. When 27 (87%) of 31 patients with molar pregnancy were first seen, circulating immune complex values were in the normal range. Three of the 4 patients with elevated levels had concurrent medical illness. Eighteen patients were followed with serial measurements until gonadotropin remission was achieved and all 18 patients developed increased levels as they entered remission (P less than .001). Circulating immune complex values remained elevated during gonadotropin remission from 6 to 16 weeks and then declined to initial levels. Further investigation should be undertaken to evaluate possible interactions between circulating immune complex and host immune defenses.

The role of cyclic adenosine monophosphate in the suppression of cellular immunity after thermal injury.

BACKGROUND AND OBJECTIVE: Cyclic adenosine monophosphate (cAMP) is an intracellular second messenger that is known to convey inhibitory signals for T-cell proliferation and function. We investigated the association between this molecule and the profound immunosuppression that accompanies thermal injury. DESIGN: Mice were randomized into two groups: one group was subjected to a 20% full-thickness scald burn; the second to a sham burn (control). The mice were killed on days 4, 7, or 10 after the burn injury and splenocytes were pooled and cultured for 15 minutes in the presence or absence of prostaglandin E2 (PGE2). RESULTS: Levels of cAMP in splenocytes were significantly elevated on day 7 after burn in the burn group compared with the sham controls (P < .05, Wilcoxon Rank Sum Test). Incubation of splenocytes with PGE2 resulted in significantly greater levels of intracellular cAMP in cells from the burn group compared with controls on days 4, 7, and 10. Incubation of normal splenocytes with dibutyryl cAMP in the presence of concanavalin A significantly decreased cell proliferation and the production of interleukin-2. The decrease in interleukin-2 production was evident at the level of messenger RNA expression. Stimulation of splenocytes with a combination of phorbol ester and calcium ionophore, bypassing all membrane-associated events prior to protein kinase C activation, reversed the inhibitory effects of dibutyryl cAMP. Incubation of splenocytes from burned animals with H-8, a selective inhibitor of cAMP-dependent protein kinases, restored the proliferative response to that of sham controls on days 4, 7, and 10 after thermal injury. CONCLUSIONS: These data indicate that elevated levels of intracellular cAMP, combined with an increased production of cAMP in response to circulating PGE2, may play a fundamental role in suppression of the immune response following thermal injury and that cAMP exerts its immunomodulatory effects prior to protein kinase C activation.

Suppression of interleukin 2 production in an animal model of thermal injury is related to prostaglandin synthesis.

We performed studies using an animal model of thermal injury to confirm the observed decrease in interleukin 2 (IL-2) production in burned patients and to explore the underlying mechanisms. Ten mice subjected to a 25% scald were compared with ten anesthetized littermates (controls) and six untreated mice (normal mice) 1, 3, 5, 7, 10, 14, and 21 days after burn. Production of IL-2 by splenocytes was stimulated by concanavalin A alone, or in the presence of the cyclooxygenase inhibitor indomethacin or flurbiprofen. The IL-2 content of the resulting supernatant was determined by the response of the IL-2-dependent cell line CTLL-2. The IL-2 production was significantly suppressed in the burned mice at three days (mean +/- SEM, 30.9% +/- 5.2%), five days (19% +/- 5.5%), seven days (41.6% +/- 6.4%), and 21 days (20% +/- 4.5%). Significant enhancement of IL-2 production by indomethacin was seen in the burned group (mean, 95%), but not in controls (mean, 23.8%) or normal mice (mean, 17.2%), and similar effects were seen with flurbiprofen. In separate experiments the effects of exogenous prostaglandin E2 on lymphocyte blastogenesis and IL-2 production were studied, and an increased susceptibility to the inhibitory effects of prostaglandin E2 was observed following thermal injury.

Interleukin-2 receptor expression and function following thermal injury.

BACKGROUND/OBJECTIVE: Serious traumatic or thermal injury is associated with depression of cellular immunity, including the failure of T-lymphocyte proliferation in response to stimulation that depends both on production of interleukin-2 (IL-2) and on expression of functional IL-2 receptors (IL-2R). While decreased IL-2 production following thermal injury is undisputed, the status of IL-2R expression and function in this setting is controversial; therefore, we sought to investigate this issue. DESIGN: A total of 220 male A/J mice (n = 22 per group) were subjected to a 20% scald burn injury or sham burn, killed 4, 7, 10, 14, or 21 days later, and splenocytes harvested. In vitro parameters of both IL-2R expression and function were measured. RESULTS: On day 7, splenic lymphocyte proliferation and IL-2 production in response to mitogenic stimulation were both suppressed following burn injury to 50% and 60% of controls, respectively. Northern blot analysis revealed normal IL-2R p55 messenger RNA expression in response to mitogenic stimulation on days 7, 10, and 14 in thermally injured animals. Phenotypic IL-2R p55 expression in concanavalin A-stimulated CD3+ cells was unchanged following burn injury. Binding of fluorescein-labeled IL-2 to cell membranes was increased in burned animals at days 10 and 14. The addition of IL-2 to cultures of spleen cells from burned mice consistently restored the mitogenic response to that of the controls. CONCLUSIONS: Thermal injury in this model does not result in either quantitative or functional suppression of IL-2R. Suppression of T-cell activation and proliferation, seen following thermal injury, appears primarily related to abnormal IL-2 production.

Modulation of macrophage hyperactivity improves survival in a burn-sepsis model.

Macrophage hyperactivity with increased production of tumor necrosis factor, interleukin 6, interleukin 1, and prostaglandins has been demonstrated in the injured patient, but the effect of this on the clinical outcome is unclear. We studied the effect of combination interleukin 1 beta and indomethacin sodium therapy on macrophage hyperactivity and survival after sepsis in a murine burn model. Macrophage interleukin 1, interleukin 6, and tumor necrosis factor alpha production were all significantly increased 10 days after thermal injury. Treatment with recombinant human interleukin 1 beta in combination with indomethacin significantly reduced this overproduction of cytokines to normal levels, and this was associated with an improvement in survival after septic challenge (52% survival in interleukin 1 beta-indomethacin-treated group compared with 22% in burned vehicle control mice). Burned mice that received either interleukin 1 beta or indomethacin alone demonstrated tumor necrosis factor and interleukin 6 production and survival intermediate between the interleukin 1 beta-indomethacin-treated group and the vehicle control group. Control of macrophage hyperactivity is associated with improved survival from subsequent sepsis and offers a potential new strategy for the treatment of immune dysfunction in thermally injured patients.

Glutathione depletion in rats impairs T-cell and macrophage immune function.

Critical illness is associated with both immunosuppression and glutathione deficiency. We determined if in vivo depletion of glutathione would adversely affect immune status. Rats with normal glutathione levels and those with glutathione stores depleted by diethyl maleate underwent analysis of splenocyte function and mesenteric lymph node lymphocyte function. Lymphocytes of the spleen and mesenteric lymph nodes were tested for concanavalin A proliferative response and interleukin 2 production. Tumor necrosis factor and interleukin 6 secretion by splenic adherent cells was also measured. Glutathione-depleted animals had significantly decreased lymphocyte proliferation and decreased production of tumor necrosis factor and interleukin 6 but unaltered interleukin 2 production. These findings indicate that in vivo glutathione deficiency impairs macrophage and T-cell function. Because glutathione depletion may occur in sepsis, trauma, and shock, treatments that help maintain glutathione levels may enhance immunocompetence and thus improve the ability of patients to recover from critical illness.

Abnormalities of antibody production after thermal injury. An association with reduced interleukin 2 production.

Antibody (Ab) production was studied in 25 burned patients who were immunized with 0.5 mg of tetanus toxoid adsorbed. Anti-tetanus toxoid (TT) Ab was measured by hemagglutination, radial immunodiffusion, and an enzyme-linked immunosorbent assay, and the results for the patients were compared with those for five similarly immunized healthy controls. As measured by hemagglutination, 12 (63%) of 19 patients had lower Ab responses than all five controls (P less than .05 by chi 2), and the median Ab response during the period of maximum response was significantly less than that in controls (8 vs 15.5 log2 maximum dilution; P = .014). After the initial response, serum Ab levels were not maintained in patients, in contrast to controls. This pattern was demonstrated by all three assays; enzyme-linked immunosorbent assay demonstrated that IgG anti-TT Ab was the major class of Ab produced. In nine patients interleukin 2 production by T lymphocytes was measured simultaneously; it was significantly depressed throughout the study except during the period from 36 to 45 days. The Ab response was also impaired in this patient group. Since maintained antibody production in response to TT is known to be T-cell dependent, these results suggest that inadequate interleukin 2 production leading to reduced T-cell help may be responsible for the lack of a persistent Ab response in these burned patients.