Neuroendocrine-immune interactions

Nutrition and the immune system: a review of nutrient-nutrient interactions

Although research on the role of single nutrients in immune function is extensive, this is not the case for multiple nutrients and subsequent nutrient-nutrient interactions. After presenting a brief overview of immune function, the authors consider reports that examine imbalance of more than one nutrient and interactive effects on immunocompetence. Availability of one nutrient may impair or enhance the action of another in the immune system, as reported for nutrients such as vitamin E and selenium, vitamin E and vitamin A, zinc and copper, and dietary fatty acids and vitamin A. Nutrient-nutrient interactions may negatively affect immune function. For example, excess calcium interferes with leukocyte function by displacing magnesium ions, thereby reducing cell adhesion. Because of consumer interest in supplementation to improve immune function, the potential for harm exists. Research is needed to improve knowledge in this area so that recommendations can be made with more confidence.

Local expression of transgene encoded TNF alpha in islets prevents autoimmune diabetes in nonobese diabetic (NOD) mice by preventing the development of auto-reactive islet-specific T cells

Lately, TNF alpha has been the focus of studies of autoimmunity; its role in the progression of autoimmune diabetes is, however, still unclear. To analyze the effects of TNF alpha in insulin-dependent diabetes mellitus (IDDM), we have generated nonobese diabetic (NOD) transgenic mice expressing TNF alpha under the control of the rat insulin II promoter (RIP). In transgenic mice, TNF alpha expression on the islets resulted in massive insulitis, composed of CD4+ T cells, CD8+ T cells, and B cells. Despite infiltration of considerable number of lymphoid cells in islets, expression of TNF alpha protected NOD mice from IDDM. To determine the mechanism of TNF alpha action, splenic cells from control NOD and RIP-TNF alpha mice were adoptively transferred to NOD-SCID recipients. In contrast to the induction of diabetes by splenic cells from control NOD mice, splenic cells from RIP-TNF alpha transgenic mice did not induce diabetes in NOD-SCID recipients. Diabetes was induced however, in the RIP-TNF alpha transgenic mice when CD8+ diabetogenic cloned T cells or splenic cells from diabetic NOD mice were adoptively transferred to these mice. Furthermore, expression of TNF alpha in islets also downregulated splenic cell responses to autoantigens. These data establish a mechanism of TNF alpha action and provide evidence that local expression of TNF alpha protects NOD mice from autoimmune diabetes by preventing the development of autoreactive islet-specific T cells.

Production of interleukin-10 in the cerebrospinal fluid in aseptic meningitis of children

IL-10 is a cytokine that has antiinflammatory properties. We investigated IL-10 using ELISA and a reverse-transcribed polymerase chain reaction in the cerebrospinal fluid (CSF) of children with or without aseptic meningitis. When the patients with aseptic meningitis had meningeal symptoms, IL-10 in the CSF was detectable in 14 of 22 patients (88 +/- 146 ng/L, n = 31). The IL-10 levels decreased as meningeal symptoms disappeared. In 20 of 21 control children without meningitis, CSF samples had no detectable levels of IL-10 (< 10 ng/L). Serum IL-10 levels were lower than the corresponding levels in the CSF from the same individuals with aseptic meningitis. Significant correlations were found between IL-10 levels and mononuclear cell counts in the CSF of the affected patients (r = 0.644, p < 0.001). The IL-10 mRNA was detected by reverse-transcribed polymerase chain reaction-assisted amplification in the CSF cells in four of seven patients with the disease. The culture of CSF mononuclear cells produced high levels of IL-10 (152-485 ng/L) in all of five patients. Cytokine kinetics in the CSF showed that mean IL-10 levels reached the peak on the 2nd to 3rd d of the illness, although all mean levels of IL-6, IL-8, and granulocyte colony-stimulating factor were the highest on the 1st d of the illness. In summary, IL-10 is produced in the CSF in aseptic meningitis, and may increase relatively late compared with the proinflammatory cytokines. IL-10 may play an immunoregulatory role in the meningeal inflammatory network.

Regulation of the immune response by epidermal cytokines and neurohormones

The ability of the cellular components of the skin immune system to mount various types of immune responses is largely dependent upon their ability to release and to respond to different signals provided by immunoregulatory mediators such as cytokines and neuropeptides. In principle, almost every cytokine known so far, including interleukins (IL), interferons (IFN), tumor necrosis factors (TNF), colony stimulating factors (CSF) and several growth factors can be detected in the skin under certain physiological or pathological conditions. There is recent evidence that neuropeptides such as substance P, calcitonin-related gene product (CGRP) a.o. as well as neurohormones such as proopiomelanocortin (POMC), which is the precursor of several peptidehormones including melanocyte stimulating hormones (MSH), are present in epidermal cells, cutaneous tumors and inflammatory cells infiltrating the skin. In addition to their well known functions as neurotransmitters or hormones, these peptides have recently been recognized as potent immunomodulating agents which inhibit the production and activity of immunoregulatory and proinflammatory cytokines (IL-1, IL-2, IFN gamma) but induce the release of factors, e.g., IL-10, which downregulate immune responses. Accordingly, in animals, alpha MSH and CGRP have been shown to inhibit the induction of contact hypersensitivity reactions. Therefore, a complex network of interacting mediators including cytokines and neuropeptides within the cutaneous microenvironment are crucial elements of the induction, elicitation and regulation of cutaneous immune responses.

Exercise and immunity: a review with emphasis on the horse

Exercise has been recognized as a stress, which can significantly alter the host's immune response and, therefore, its susceptibility to disease. Whereas research in this area has previously focused primarily on human subjects and laboratory animals, it has more recently extended to domestic animals, especially the equine athlete. Despite several studies, defining the relationship among exercise, the immune response, and disease has proven difficult due to a number of factors, including the complexity of the immune system and the variable nature of exercise itself. It now appears that exercise has dual effects on the immune system. Suppressive effects, such as a decline in the ratio of CD4+ to CD8+ cells, diminished lymphocyte function, and a decline in the number and cytolytic activity of natural killer cells have been observed in response to brief high-intensity exercise, prolonged exhaustive exercise, and overtraining. In contrast, moderate training generally has beneficial effects on host defense mechanisms. The mechanisms for regulating the dual effects of exercise are complex, involving a network of neuroendocrine hormones and cytokines.

Molecular characterization of immune derived proenkephalin mRNA and the involvement of the adrenergic system in its expression in rat lymphoid cells

Proenkephalin (PENK), a classically defined opioid gene, was originally thought to be expressed almost exclusively in the mature nervous and neuroendocrine systems. In the last few years, it was demonstrated, however, that significant levels of PENK mRNA and PENK-derived peptides are transiently expressed in cells of the immune system. Very little is known about the molecular mechanisms regulating this transient expression. In order to investigate those mechanisms, we examined the in vivo expression of PENK mRNA in mesenteric lymph nodes after exposing rats to lipopolysaccharide. In the present study we demonstrate that: (i) promoter usage and splicing of PENK mRNA function similarly in mesenteric lymph nodes as in neural cells; (2) PENK expression in mesenteric lymph nodes is modulated by adrenaline via adrenergic receptors; and (3) the adrenergic system participates in the modulation of the LPS induced PENK mRNA expression. These results provide more evidence for the involvement of opioids in neuro-immune interactions.

Induction of immunoreactive interleukin-1 beta and tumor necrosis factor-alpha in the brains of rabies virus infected rats

Interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF alpha) are important cytokines in the development of brain inflammation during pathological process. During rabies virus infection, the level of these proinflammatory cytokines are enhanced in the brain. In the present study we determined the cellular localization of these two cytokines by immunocytochemistry in brains of rats infected with rabies virus, at different time-intervals of the disease (day 1, 3, 4, 5 and at final stage day 6 post-infection (p.i.)). Cellular identification of IL-1 beta (irIL-1 beta) and TNF alpha (irTNF alpha) immunopositive cells was studied using a polyclonal antibody against these cytokines and against glial fibrillary acidic protein (GFAP) to detect astrocytes and GSA-I-B4 isolectin to detect microglial cells and/or infiltrating macrophages. In brains of control and early infected rats, irIL-1 beta was only detected in fibers located in the hypothalamus, supraoptic and tractus optic nuclei and infundibular nucleus. From day 4 onwards until day 6 p.i., enhanced irIL-1 beta was found and identified either in activated ameboid and/or infiltrated macrophages (amygdala, thalamus, internal capsula, subtantia nigra, septal nuclei and around blood vessels), or in activated ramified cells (hypothalamus and periventricular nucleus, piriformis and cingulate cortex, hippocampus). IrTNF alpha was observed in the brains of rats at a final stage of disease (day 5 and 6 p.i.): in the hypothalamus, the amygdala, the internal capsula, the thalamus, the septal nuclei, the hippocampus, the habenular nuclei and around the blood vessels. Ir-TNF alpha was detected in round cells identified as ameboid microglia and/or infiltrated macrophages. A marked activation of microglial and astroglial cells was observed mainly in the hypothalamus, the thalamus and hippocampus and around the blood vessels, at day 4 p.i. and later, revealing a high central inflammatory reaction in brains of rabies virus infected rats. These results showed that IL-1 beta and TNF alpha are produced in the brain both by local microglial cells and infiltrating macrophages during rabies infection. Thus, these cytokines may play an important role in coordinating the dramatic inflammatory response associated with the rabies-encephalopathy as well as in the neural modification and alteration of brain functions.

Subdiaphragmatic vagotomy inhibits intra-abdominal interleukin-1 beta stimulation of adrenocorticotropin secretion

Although interleukin (IL)-1 beta activates the hypothalamic-pituitary-adrenal (HPA) axis, the mechanisms by which peripheral IL-1 beta acutely stimulates adrenocorticotropin (ACTH) secretion are not clear. Recently, the vagus has been implicated in mediating peripheral cytokine signalling of the brain. To investigate a possible central mechanism for peripheral cytokine stimulation of the HPA axis, we tested the hypothesis that the vagus mediates IL-1 beta activation of the HPA axis by an intra-abdominal stimulus. We studied the effect of subdiaphragmatic vagotomy on plasma ACTH stimulation in rats by intraperitoneal (i.p.) IL-1 beta. Adult male Sprague-Dawley rats underwent subdiaphragmatic vagotomy or sham surgery 1 week prior to study. Rats were killed 1 and 2 h after i.p. saline (control) and low- (4 micrograms/kg) and high-dose (20 micrograms/kg) IL-1 beta. Vagotomy markedly attenuated plasma ACTH secretion at 2 h after high-dose IL-1 beta stimulation and abolished plasma ACTH secretion at 2 h after low-dose IL-1 beta stimulation. At 1 h after low-dose IL-1 beta, stimulation of plasma ACTH in vagotomized animals was also markedly diminished compared to sham animals. However, vagotomy did not alter stimulation of plasma corticosterone at 1 or 2 h after low-dose IL-1 beta or at 2 h after high-dose IL-1 beta. In addition, vagotomy did not alter stimulation of plasma ACTH or corticosterone secretion by insulin-induced hypoglycemia. We conclude that: (1) the vagus plays an important role in stimulation of ACTH secretion by intra-abdominal (i.p.) IL-1 beta; (2) stimulation of corticosterone secretion by i.p. IL-1 beta is not altered by vagotomy; and (3) the inhibitory effect of vagotomy on activation of the HPA axis appears to be specific for immune stimulation by cytokines.

Somatostatin analogue treatment of neuroendocrine tumours

The long-acting analogues of somatostatin have an established place in the medical treatment of patients with neuroendocrine tumours. They act through binding with specific, high-affinity membrane receptors. Somatostatin analogue therapy is an effective and safe treatment for most growth hormone and thyrothropin-secreting pituitary adenomas. The potential therapeutic consequences of the presence of somatostatin receptors on clinically 'nonfunctioning' pituitary tumours are still uncertain. Somatostatin analogues are not useful in the treatment of patients with prolactinomas, or adrenocorticotropin (ACTH)-secreting adenomas. However, the somatostatin analogue octreotide suppressed pathological ACTH release in some patients with Nelson's syndrome and ACTH and cortisol secretion in several patients with Cushing's syndrome caused by ectopic ACTH secretion. Somatostatin analogues are effective in the sympatomatic treatment of most (metastatic) pancreatic islet cell tumours and most (metastatic) carcinoids. In some of these patients, they also induce tumour stabilisation or reduction. In some patients with (metastatic) medullary thyroid carcinomas, continuous treatment with very high doses of octreotide can be of temporary relief. The clinical effectiveness of somatostatin analogues in patients with small cell lung cancer is currently under investigation. Long-term therapy with somatostatin analogues of catecholamine-secreting (malignant) paragangliomas and phaeochromocytomas has not shown clinical benefits.

Fetal and maternal endocrine responses to experimental intrauterine infection in rhesus monkeys

OBJECTIVE

Our purpose was to describe the temporal and quantitative relationships among intrauterine infection, fetal-placental steroid biosynthesis, and preterm labor in a nonhuman primate model.

STUDY DESIGN

On approximately day 130 of gestation (term 167 days) chronically instrumented rhesus monkeys (Macaca mulatta) were infected with 10(6) colony-forming units of group B streptococci either by intraamniotic (n = 4) or choriodecidual (n = 2) inoculation. As controls, four additionally chronically instrumented noninfected monkeys were followed up to spontaneous parturition. Amniotic fluid and maternal and fetal arterial blood were serially sampled in all monkeys (both before and after infection) for progesterone, estrone, estradiol, dehydroepiandrosterone, dehydroepiandrosterone sulfate, androstenedione, and cortisol by specific radioimmunoassays, and uterine activity was continuously recorded.

RESULTS

Spontaneous parturition was preceded by gradual and significant increases in the plasma concentrations of fetal dehydroepiandrosterone, dehydroepiandrosterone sulfate, and androstenedione and fetal and maternal levels of estrone, estradiol, and progesterone but not by changes in cortisol. In contrast, infection-associated parturition (either intraamniotic or choriodecidual) was characterized by abrupt increases in fetal dehydroepiandrosterone, dehydroepiandrosterone sulfate, androstenedione, progesterone, and cortisol but not by increases in maternal or fetal estrone or estradiol. Infection-associated steroid changes occurred concurrently with or after increases in uterine activity.

CONCLUSION

Infection-associated preterm parturition is associated with dramatic increases in fetal adrenal steroid biosynthesis but not by corresponding increases in placental estrogen biosynthesis. This suggests that fetal stress in accompanied by placental dysfunction and that infection-associated parturition is not dependent on the increased estrogen biosynthesis observed in spontaneous parturition.

Contact allergies to nickel sulfate, gold sodium thiosulfate and palladium chloride in patients claiming side-effects from dental alloy components

397 patients claiming various subjective symptoms related to dental restoration materials have been tested for the presence of metal allergy. The resultant data have been compared with the corresponding allergies of eczematous patients. The frequency difference of metal allergy in the dental group is statistically significant or close to significance for nickel sulfate, potassium dichromate, cobalt chloride, palladium chloride and gold sodium thiosulfate. The findings suggest that the dental patient group represents a subgroup with a high frequency of metal allergy.

Prospects and advances in hormonal immunomodulatory therapy

Modulation of the immune network through the hormonal system is an exciting emerging concept. It results from a decade of experimental research obtained on rodents. Unfortunately, the therapeutic response on NZB/NZW F1 mice with murine lupus or in adjuvant induced arthritis are not transferable to man. This new field opens new therapeutic perspectives with well known and relatively safe drugs (hormone agonists, antagonists or inhibitors of hormonal secretion). Today we lack controlled, randomized clinical studies, with long-term follow-up. We also need to identify the subgroup of patients who could benefit from hormonal immunomodulation (sex, basal hormonal status, menopausal status for women, disease activity).

The immune system

OBJECTIVE

To explain the role of the immune system in cancer control and its response to environmental and perceived stressors.

DATA SOURCES

Review articles, research studies, and book chapters related to immunology and the immune system.

CONCLUSIONS

The immune system responds to foreign pathogens and cancer cells by activating specific and nonspecific immune responses. The goal of immunotherapy is to enhance these responses to control the growth of cancer cells. Knowledge of the influence of stress on immune and cytokine response is evolving.

IMPLICATIONS FOR NURSING PRACTICE

Knowledge of the principles of immunology, the immune response to cancer, the role of cytokines in mediating immune response, and the influence of stress on immune and cytokine response will help nurses provide quality care to patients receiving biological agents.

Alteration of muscarinic acetylcholine receptors in rabies viral-infected dog brains

Functions of the muscarinic acetylcholine receptor (mAChR) were studied in rabid dog brains using [3H]quinuclidinyl benzilate (QNB) as a radioligand. Of various brain regions, hippocampus and brainstem were the areas mostly affected in terms of impaired specific binding to [3H]QNB, as compared to other regions, as well as to those of controls. Saturation studies of the hippocampus revealed significantly elevated dissociation equilibrium constant (K(d)) values in both furious (n = 5) (9.80 + or - 2.77 nM) and dumb (n = 6) (6.01 + or - 1.08 nM) types of rabies as compared to 11 controls (2.15 + or - 0.31 nM), whereas the maximum number of receptor sites (B (max)) values were comparable among all subgroups of normal (1.38 + or - 0.10 pmol/mg protein), dumb (1.43 + or - 0.17 pmol/mg protein) and furious (1.28 + or - 0.12 pmol/mg protein) rabies types. Hippocampal K(d) values were comparable between high (fluorescent antibody test-FAT and polymerase chain reaction-PCR positive; n = 4) (7.47 + or - 3.27 nM), and low (FAT-negative and PCR-positive; n = 4) virus amount (8.34 + or - 3.93 nM) but these were significantly higher than controls (n = 4) (1.58 + or - 0.17 nM). Our data suggest a functional derangement of mAChR at specific sites of hippocampus and brainstem which is not dependent on the amount of virus.

Alcohol stimulates ACTH secretion in the rat: mechanisms of action and interactions with other stimuli

This review discusses some of the mechanisms through which alcohol (EtOH) alters the activity of the hypothalamic-pituitary-adrenal (HPA) axis. In adult rats, acute EtOH treatment increases plasma ACTH and corticosteroids levels primarily by stimulating the release of corticotropin-releasing factor (CRF) and possibly vasopressin (VP) from nerve terminals in the median eminence. Increased CRF gene transcription in the hypothalamus may also be important. The HPA axis remains activated during chronic EtOH exposure, although habituation may take place. Changes in the responsiveness of hypothalamic neurons, a phenomenon itself dependent in part on a number of intermediate secretagogues, as well as decreased pituitary responsiveness to VP, all play a role. Finally, the activity of the HPA axis is influenced by exposure to EtOH during embryonic development, with mature offspring showing hyporesponsiveness to many stimuli. These altered responses appear to be caused in part by changes in the synthesis/release CRF, possibly under the influence of nitric oxide. CRF, VP, ACTH, and corticosteroids are important regulators of the immune system, behavior, metabolic pathways, and reproductive parameters. Alcohol therefore may influence such functions through the pathological secretion of these hormones. A better understanding of the mechanisms through which the drug alters their release thus may permit the development of therapies designed to alleviate some of the consequences of alcoholism.

Acute stimulation of the hypothalamic-pituitary-adrenal axis by IL-1 beta, TNF alpha and IL-6: a dose response study

We investigated the effects of i.v. and intracerebroventricular (i.c.v) administration of increasing doses of recombinant human IL-1 beta, TNF alpha and IL-6 on plasma corticosterone (B) levels in rats. Rats were equipped with a jugular cannula for repeated blood sampling anda subgroup of rats also received an i.c.v implanted cannula. I.v. administration of IL-1 beta, TNF alpha or IL-6 and i.c.v administration of IL-1 beta and IL-6 induced a significant dose-dependent increase in plasma B levels, whereas i.c.v injection of TNF alpha in doses up to 1000 ng/rat was not effective. I.v. pretreatment of rats with anti-CRH antiserum had no significant overall effect on the plasma B response to i.v. administered IL-1 beta (500 and 3000 ng/rat), whereas the plasma B response to i.v. TNF alpha or IL-6 administration (3000 ng/rat) were significantly reduced. I.v. pretreatment of the animals with recombinant human IL-1 receptor antagonist (IL-1ra) significantly blocked the plasma B response to i.v. treatment with IL-1 beta, whereas the TNF alpha- and IL-6-induced increases in plasma B levels were not affected. Our data show that 1) i.v. administration of IL-beta, TNF alpha or IL-6 and i.c.v administration of IL-1 beta or IL-6 dose-dependently stimulate the HPA axis; 2) when given i.v. or i.c.v, IL-1 beta is more powerful than TNF alpha and IL-6 in activating the HPA axis; 3) endogenous CRH is involved in the activation of the HPA axis by acute i.v. administration of TNF alpha and IL-6. It is most likely that in case of i.v. treatment with IL-1 beta a CRH-independent mechanism is involved. This study provides no arguments for the involvement of endogenous IL-1 in TNF alpha- or IL-6-induced activation of the HPA axis.

Lipopolysaccharide-induced lethality and cytokine production in aged mice

This study was designed to define the lipopolysaccharide (LPS) sensitivity of aged mice in terms of lethality and cytokine production and to determine down-regulating responses of corticosterone and interleukin 10 (IL-10). The 50% lethal doses of LPS in young (6- to 7-week-old) and aged (98- to 102-week-old) mice were 601 and 93 microg per mouse (25.6 and 1.6 mg per kg of body weight), respectively. Aged mice were approximately 6.5-fold more sensitive to the lethal toxicity of LPS in micrograms per mouse (16-fold more sensitive in milligrams per kilogram) than young mice. Levels in sera of tumor necrosis factor-alpha (TNF-alpha) IL-1alpha, and IL-6 after intraperitoneal injection of 100 microg of LPS peaked at 1.5, 3, and 3 h, respectively, and declined thereafter in both groups of mice. However, the peak values of these cytokines were significantly higher in aged than in young mice (P < 0.05). Gamma interferon (IFN-gamma) was detectable at 3 h, and sustained high levels were still detected after 12 h in both age groups. Although there were no significant differences in levels of IFN-gamma in sera from both groups, aged mice showed higher IFN-gamma levels throughout the 3- to 12-h study period. Administration of increasing doses of LPS revealed that aged mice had a lower threshold to IL-1alpha production than young mice. In addition, aged mice were approximately 4-fold more sensitive to the lethal toxicity of exogenous TNF in units per mouse (10-fold more sensitive in units per kilogram) than young mice. With regard to down-regulating factors, corticosterone amounts were similar at basal levels and no differences in kinetics after the LPS challenge were observed, whereas IL-10 levels in sera were significantly higher in aged mice at 1.5 and 3 h than in young mice (P < 0.01). These results indicate that aged mice are more sensitive to the lethal toxicities of LPS and TNF than young mice. We conclude that a relatively activated, or primed, state for LPS-induced cytokine production, in spite of full down-regulating responses by corticosterone and IL- 10, may explain at least in part LPS sensitivity in aged mice.

Expression of the somatostatin gene in human astrocytoma cell lines

Somatostatin (somatotropin release-inhibiting hormone; SRIH) has been demonstrated in neurons of the central nervous system (CNS) as well as in endocrine cells of the pancreas and gastrointestinal tract and can suppress various immune functions including lymphocyte proliferation, immunoglobulin synthesis, and cytokine production. Since astrocytes possess antigen-presenting activity and can secrete a wide array of immunoregulatory and inflammatory cytokines, we studied SRIH gene expression in both astrocyte cell lines and mitogen-stimulated peripheral blood mononuclear leukocytes from healthy donors. We now report by means of a complementary DNA-based reverse transcription PCR that differential levels of SRIH mRNA were expressed in 9 of 11 human astrocytoma cell lines tested but were undetectable in activated peripheral blood mononuclear leukocytes as well as in a variety of human lymphocyte and monocyte cell lines. The synthesis and secretion of SRIH protein by astrocytoma cells that expressed SRIH transcripts were confirmed by specific radioimmunoassay of cell culture fluids. These findings support the notion that SRIH gene expression occurs in human astrocytoma cells but not in mature lymphoid cells of the immune system.

Review article: refractory distal colitis -- explanations and options

Distal colitis refractory to standard therapy is a complex and challenging problem. Physiological differences between the right and left colon may be exploited for maximum therapeutic benefit. Over-reliance on oral therapy should be seen as one of the reasons for treatment failure and delivery systems should target therapy to the distribution of the disease in doses proven to be therapeutically beneficial. The clinician should also be cognizant of potential adverse effects of standard therapies, particularly colitis due to mesalazine, which may mimic worsening disease. Numerous endogenous and exogenous factors that may exacerbate the underlying inflammatory bowel disease are discussed. This review explores the potential mechanisms why distal colitis may be refractory to therapy and addresses newer therapies that, while still in the investigatory stages, offer hope for a widening armamentarium of therapeutic modalities.

Psychoneuroimmunology of autoimmune disorders

The interactions between the immune system and psychological states are both intricate and intriguing. Research at a molecular level has thrown considerable light on the previously ill-defined area of psychoneuroimmunology. In this report, we explore the psychoneuroimmunology of autoimmune disorders, particularly rheumatoid arthritis and lupus erythematosus. Animal models of these diseases have provided a particularly useful window on complex psychoneuroimmunological interactions. Observations about the effect of stress on the onset and course of autoimmune disorders has added to our understanding of psychoneuroimmunological interactions. These interactions are bi-directional, as reflected in the autoimmune-mediated neuropsychiatric manifestations of systemic lupus. Exploring the role of various neurotransmitters and neuromodulators in the stress response may have important therapeutic implications for autoimmune disorders.

Enhancement of phagocytosis by calcitonin gene-related peptide (CGRP) in cultured mouse peritoneal macrophages

Calcitonin gene-related peptide (CGRP) is widely distributed in sensory neurons and nerve fibers. To clarify the function of CGRP on the immune system, the effect of CGRP on phagocytosis by peritoneal macrophages was examined by means of flow cytofluorometry. CGRP enhanced phagocytosis of latex beads in a dose-dependent manner. Because the phosphodiesterase inhibitor 3-isobutyl, 1-methylxanthine (IBMX) enhanced the CGRP-induced enhancement of phagocytosis, the enhancement might be mediated by cAMP. In the presence of mannan, the phagocytosis was suppressed and the CGRP-induced enhancement was also blocked, suggesting that mannose receptors on macrophages were involved in mediating the phagocytosis of latex beads, and CGRP enhanced the mannose receptor-mediated phagocytosis. The present results indicate that CGRP can modulate the function of macrophages in nerve terminals of sensory neurons during the development and maintenance of inflammation.

Functional and molecular characterization of VIP receptors and signal transduction in human and rodent immune systems

In the last few decades, as a result of the interaction between different areas of research, the new interdisciplinary and exciting field of neuroimmunology has emerged. In this context, it has been demonstrated that small peptides may function in a communication network that links nervous, endocrine, and immune systems. Thus, each peptide may function as a neurotransmitter, peptide hormone, or cytokine, depending on its site of release and the target cell with which it interacts. Among these peptides, vasoactive intestinal peptide (VIP) has been shown to play a very important role in the regulation of immune function. The first stage in the action of VIP with immunocompetent cells is the binding to specific plasma membrane receptors and the generation of an intracellular signal. In this review, we focus and present data about the signal transduction pathway of VIP in both human and rodent immunocompetent cells.

Cytokines in the ovary: pathophysiology and potential for pharmacological intervention

The ovary and testis are sites for interaction between the endocrine and immune system via leukocytes and their secreted products, the cytokines. There are convincing data available to show that the gonads are sites of cytokine action and production. In the ovary, cytokines and leukocytes are intimately involved in follicular development, ovulation, and luteal function. A variety of clinical situations may be due to cytokine action in the gonads, and therapeutic manipulation of the immune system may affect reproductive function.

The protective role of the hypothalamic-pituitary-adrenal axis against lethality produced by immune, infectious, and inflammatory stress

We have shown that ADX and HYPOX rats exhibit a markedly increased sensitivity to the lethal effects of IL-1-beta and LPS compared to sham controls with an intact HPAA. These results indicated that the reports of lethal effects of cytokines and LPS which generates cytokines in mice with a compromised HPAA were not idiosyncratic or specific to mice but represented a general response that would have been expected in any organism with a compromised HPAA. We further demonstrated that protection against lethal effects due to IL-1-beta or LPS could be produced by treating ADX rats with glucocorticoid in a quantity estimated to be equivalent to corticosterone secretion provoked during stress. In contrast, we found that acutely stalk-sectioned rats with pituitaries disconnected from hypothalamic regulation did not show a markedly increased susceptibility to lethal effects of LPS as did ADX or HYPOX rats. Although a minority of stalk-sectioned rats were killed by LPS, the majority of rats were protected from lethal actions of LPS. This response suggested that an intact pituitary-adrenal axis without the normal hypothalamic control could still provide significant protection presumably due to generation of cytokines which stimulated the pituitary over several hours. The results from our lethality studies clearly underscore the importance of activating the stress axis and increasing glucocorticoid secretion to protect against potentially lethal effects of cytokines that can be induced by immune, infectious, or inflammatory stimuli. Cytokine-stimulated effects can initially result in beneficial actions to the host by promoting immune/inflammatory responses that are protective in nature and help defend against a variety of invading stimuli (infectious, immune, inflammatory, traumatic, neoplastic). Normally the HPAA responds to cytokine stimulation by ultimately increasing glucocorticoid secretion in order to counterregulate cytokine actions, modulate the host response, and protect the host from excessively catabolic effects of unregulated cytokine generation and actions. For many years, clinicians have recognized that patients with deficient glucocorticoid secretion (e.g., Addison's disease or pituitary ACTH deficiency) require increased glucocorticoid replacement during episodes of fever, infection, or inflammatory stress. However, the reasons why stress-equivalent glucocorticoid replacement were required were not entirely clear. Now, we understand that glucocorticoids are critically important for protecting the host against its own defense mechanisms so that the stimulation of cytokines can facilitate a protective response against an invading insult without also killing the host.

Replacement of DHEA in aging men and women. Potential remedial effects

DHEA in appropriate replacement doses appears to have remedial effects with respect to its ability to induce an anabolic growth factor, increase muscle strength and lean body mass, activate immune function, and enhance quality of life in aging men and women, with no significant adverse effects. Further studies are needed to confirm and extend our current results, particularly the gender differences.

Autoimmune thyroid disease in primary Sjögren's syndrome

PURPOSE

To evaluate the prevalence of autoimmune thyroid disease and thyroid dysfunction in patients with primary Sjögren's syndrome.

PATIENTS AND METHODS

Thyroid function of 33 patients with primary Sjögren's syndrome was clinically and biochemically evaluated. Thyroid hormones and autoantibodies against thyroid peroxidase, thyroglobulin, and thyroid hormones were measured.

RESULTS

Autoimmune thyroid disease and thyroid dysfunction were found in 15 cases (45%): autoimmune thyroiditis in 8 (24%); autoimmune hyperthyroidism in 2 (6%); and reversible iodine-induced hypothyroidism in the remaining 5 (15%). One or more of the evaluated autoantibodies were detected in 8 euthyroid patients (24%). Overall, the prevalence of autoantibodies against thyroid peroxidase, thyroglobulin, thyroxine, and triiodothyronine was 45%, 18%, 42%, and 36%, respectively.

CONCLUSIONS

The high prevalence of autoimmune thyroid disease and thyroid dysfunction found in primary Sjögren's syndrome, using sensitive immunologic and thyroid function tests, suggest that both diseases are more frequently associated than it was previously thought, and should be sought clinically and by laboratory tests in all patients with primary Sjögren's syndrome.

From health locus of control to immune control: internal locus of control has a buffering effect on natural killer cell activity decrease in major depression

Decreased immunity in depressive as compared with control subjects has been well documented, although some depressed patients have severe alterations whereas others have milder ones or not at all. Since for equal severities of depression, there may be individual differences in the degree of perceived control over one's condition, we investigated the interaction of perceived control with immunological variations. Immune function (T and B lymphocytes, lymphocyte proliferation and natural killer cell activity (NKCA)) were evaluated in 34 adult major depressives and in 18 healthy controls. Lymphocyte proliferation did not differ between the two groups, but NKCA was significantly lower in the depressed patient group. Among the depressed subjects, those who experienced less subjective control also showed significantly lower NKCA. An internal locus of control appears to act as a buffer against the decrease in cellular immunity observed in major depression. Further studies should focus on methods of coping and on degree of perceived control rather than on diagnostic and nosographic variables alone.

The role of endogenous glucocorticoids in rat experimental models of acute pancreatitis

BACKGROUND & AIMS

Cytokines activate the hypothalamic-pituitary-adrenal axis and suppress inflammation by stimulating glucocorticoid secretion. The state of adrenocortical function during acute pancreatitis and its role in this disease were determined.

METHODS

Cerulein-induced pancreatitis or closed duodenal loop pancreatitis was produced in rats that had undergone adrenalectomy or sham adrenalectomy, and the serum corticosterone and interleukin 8 levels and the intensity of the pancreatitis were examined.

RESULTS

Serum corticosterone levels were significantly higher than basal levels in both models of experimental pancreatitis. In both models, adrenalectomy increased serum amylase and pancreatic edema and produced more severe inflammation. Adrenalectomy significantly increased mortality in animals with closed duodenal loop pancreatitis. Exogenous hydrocortisone administered to adrenalectomized animals suppressed the elevation of serum interleukin 8 levels and decreased both the severity of pancreatitis and mortality.

CONCLUSIONS

These results suggest that the adrenocortical function is stimulated during acute pancreatitis and that the secretion of endogenous glucocorticoids may play an important role in mitigating the progress of this disease, probably by inhibiting cytokine production.

Systemic lupus erythematosus: immunopathogenesis of neurologic dysfunction

Neurologic complications of systemic lupus erythematosus (neuro-SLE) are common. The most frequent manifestations of neuro-SLE are seizures, encephalopathy, and behavioral changes, but a wide variety of other neurologic abnormalities affecting the central and peripheral nervous system and muscle also occur. Although the prevalence of neuro-SLE is high, the diversity of clinical presentations, the multiple potential etiologies, and the absence of sensitive and specific diagnostic tests render diagnosis difficult. Recent advances in understanding mechanisms of neuronal dysfunction combined with advances in imaging techniques, including functional imaging, should help in diagnosis and management. The mechanisms of neurologic injury can be divided into three broad categories. First, neuronal dysfunction may result from direct effects of the immune system on brain cells such as autoantibody binding to cell surface, immune complex deposition with secondary inflammation, and effects of cytokines. Second, immune- mediated injury to supportive structures such as the vasculature may also affect the nervous system by producing ischemia. Finally, the neuraxis may be affected by any one of several immune and non- immune effects of infection, toxins, and metabolic disturbances.

Testicular dysfunction in human immunodeficiency virus-infected men

This review pertains to gonadal function in men with human immunodeficiency virus (HIV) infection, who often exhibit clinical and biochemical evidence of hypogonadism. Hypogonadotropic hypogonadism appears to be the most commonly encountered abnormality, although complete anterior pituitary insufficiency and primary gonadal failure have been reported. Levels of sex hormone-binding globulin (SHBG) are either unchanged or increased. Plasma levels of estrogens, progesterone, androstenedione, dehydroepiandrosterone sulfate (DHEA-S), and prolactin vary. Pathologically, except for involvement by opportunistic infections, no significant abnormality in the hypothalamic-pituitary area has been described, but evidence of orchitis is commonly present. The cause(s) of these abnormalities remains unclear. The possible factors leading to hypogonadism in HIV-infected men include HIV infection itself, opportunistic infections, chronic debilitating illness, and effects of cytokines on the hypothalamic-pituitary-gonadal axis. Further studies are needed to clarify the cause(s) of testicular dysfunction in HIV-infected men and its clinical significance, treatment, relevance to the progression of HIV infection, and influence on the immune system.

Clinical trials of antidepressants: the hidden face: where locus of control appears to play a key role in depression outcome

It remains difficult to determine in what measure improvements observed in clinical trials of anti-depressants may be attributable to the psychological predispositions of the subjects. The present article focuses on the effect of a psychological variable, the Health Locus of Control, which measures the extent of a subject's belief that he is in control over his own health. The hypothesis is that depressed subjects whose locus of control is internal, i.e. who perceive themselves to be in control, rather than external, i.e. control perceived as being in others or just chance, will improve more markedly and consistently on the Hamilton Depression Rating Scale, across a number of clinical trials. Forty-nine depressive patients undergoing treatment with four different compounds were included, after a week's placebo run-in period, in a classical 42-day follow-up study comprising visits on days -7, 0, 10, 21; and 42. Interactions between the type of locus of control and the clinical course were investigated by MANOVA. Results show that with a classical design of clinical trials of antidepressants, locus of control plays a significant role if it is internal (P < 0.001) in consolidating the improvement process, and that this is true irrespective of type of antidepressant. The relationship between the concept of locus of control and placebo effect is discussed.

Neuropathogenic actions of cytokines assessed in transgenic mice

Cytokines are potent biological response modifiers that exhibit a spectrum of cellular actions. These factors have been implicated as important mediators of physiologic and possibly pathophysiologic processes within the CNS. Targeting the expression of cytokines to specific tissues in transgenic mice has provided a powerful approach to the investigation of complex cellular responses at a localized level and also recapitulated more closely the expression of these mediators as found in pathogenetic processes. This review will focus on the recent application of transgenic technology to achieve the specific cerebral expression of cytokines. The targeting of cytokine gene expression to astrocytes in transgenic mice has provided new and dramatic insights into the CNS pathobiology of these host-response molecules. Specifically: (1) transgenic expression of the cytokines IL-6, IL-3 and IFN-alpha in the CNS results in the development of acute (high expression) or chronic progressive (low expression) CNS disease associated with a spectrum of clinical, physiologic and pathologic manifestations; (2) although the clinical, cellular and molecular phenotype produced by the cerebral expression of the various cytokines showed some overlap, the differences were more prominent reflecting the unique actions of each cytokine; (3) these transgenic models which recapitulate many of the structural and functional impairments seen in human neurodegenerative diseases, highlight the point that cytokines, which normally function as primary regulators of the host response, also have the potential to mediate significant injury in the CNS. Therefore, these transgenic models have provided a valuable tool for advancing our understanding of the CNS pathobiology of cytokines and will no doubt offer a unique resource for the development and testing of therapies aimed at abrogating the toxic actions of these important mediators.

Blood levels of cytokines in brain-dead patients: relationship with circulating hormones and acute-phase reactants

We hypothesized that increased levels of blood cytokines occur in brain-dead patients, and that these cytokines are responsible for some of the endocrine and/or acute-phase reactant abnormalities found in these patients. We measured blood levels of cytokines, hormones, and acute-phase reactants in 18 brain-dead potential organ donors at the moment of establishing the legal diagnosis of brain death and compared them with levels found in a control group. Although interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) levels were within the normal range, interleukin-6 (IL-6) levels were clearly above the normal range in all patients (median, 1,444 pg/mL; range, 75 to 11,780). In the brain-dead group, total thyroxine (tT4), free T4 (fT4), triiodothyronine (T3), thyrotropin (TSH), dehydroepiandrosterone sulfate (DHEA-S), testosterone, albumin, Zn, and osteocalcin levels were decreased, T3 resin uptake index (T3 RUI), corticotropin (ACTH), cortisol, 11-deoxycortisol (11-DOC), 17-hydroxyprogesterone (17-OHPr), aldosterone, luteinizing hormone, and follicle-stimulating hormone levels were normal, and reverse T3 (rT3), renin, and C-reactive protein (CRP) levels were increased. Multiple regression analysis demonstrated significant interrelations between IL-6 and T4, T3, testosterone, and CRP. We also studied the evolution of some of these parameters in four patients with severe head injury who finally developed brain death. IL-6 levels on admission to the intensive care unit (ICU) were above the normal limits, as in other patients with cranial trauma, but when the patients developed brain death, there was a pronounced increase in IL-6 levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Synergism between IL-1 beta and TNF-alpha on the activity of the pituitary-adrenal axis and on food intake of rats

We investigated the effects of separate and combined intraperitoneal administration for 3 days of recombinant human interleukin-1 beta (IL-1) and recombinant human tumor necrosis factor-alpha (TNF) on plasma adrenocorticotropic hormone (ACTH) and corticosterone (B) levels, adrenal weight, food intake, and rectal temperature. Rats were equipped with a jugular cannula for daily blood sampling and with an intraperitoneally implanted Alzet osmotic minipump loaded with either saline, IL-1 (2.0 micrograms/day), TNF (0.2, 2.0, or 10.0 micrograms/day), or IL-1 in combination with TNF. Plasma ACTH and B levels and adrenal weight were significantly increased, in a dose-dependent way, by simultaneous infusion of IL-1 and TNF but not by administration of either cytokine alone. Chronic administration of IL-1 alone induced a significant decrease in food intake and a significant elevation of rectal temperature, whereas infusion of only the highest dose of TNF significantly elevated rectal temperature. Coinfusion of IL-1 and TNF induced both effects in a dose-dependent and synergistic way. Our data show that simultaneous infusion of IL-1 and TNF in rats has a synergistic effect on the activity of the pituitary-adrenal axis as well as on food intake and rectal temperature. The existence of two pathways, which act synergistically, may increase the sensitivity of the host to respond to subtle inflammatory stimuli.

Immunomodulatory role of melatonin: specific binding sites in human and rodent lymphoid cells

This paper reviews the evidence that supports the hypothesis of the existence of specific binding sites for melatonin on immune cells. These binding sites have been described in human blood lymphocytes and granulocytes, and thymus, spleen, and bursa of Fabricius from different rodents and birds. The dissociation constant values of these binding sites are in the 0.1-1 nM range, suggesting that melatonin may play a physiological role in lymphocyte regulation. Moreover, melatonin binding sites appear to be modulated by guanine nucleotides. Therefore, in addition to other mechanisms described for the regulation of immune function by melatonin, a direct mechanism of regulation can be involved via binding of melatonin by immunocompetent cells.

Human and murine pituitary expression of leukemia inhibitory factor. Novel intrapituitary regulation of adrenocorticotropin hormone synthesis and secretion

Leukemia inhibitory factor (LIF) gene expression was detected in human fetal pituitary tissue by expression of LIF mRNA transcripts, protein immunocytochemistry, and immunoelectron microscopy. Fetal LIF immunoreactivity colocalized with 30% of ACTH-expressing cells, approximately 20% of somatotrophs, and approximately 15% of non-hormone-expressing cells. LIF was also strongly expressed in normal adult pituitary and in four growth hormone-producing and two ACTH-producing adenomas, but not in eight nonfunctioning pituitary tumors. Culture of fetal cells expressing surface LIF-binding sites demonstrated predominance of in vitro ACTH secretion as compared with other pituitary hormones. In AtT-20 murine cells, LIF (ED50 10 pM) stimulated basal proopiomelanocortin mRNA levels by 40% and corticotropin-releasing hormone-induced ACTH secretion (two- to threefold), as did oncostatin M (ED50 30 pM), a related peptide. ACTH responses were not further enhanced by both cytokines together, which is consistent with their shared receptor. Anti-LIF antiserum neutralized basal and LIF-induced ACTH secretion, suggesting autocrine regulation of ACTH by LIF. The results show that human pituitary cells express the LIF gene and LIF-binding sites, predominantly in corticotrophs. Pituitary LIF expression and LIF regulation of proopiomelanocortin and ACTH reflect an intrapituitary role for LIF in modulating early embryonic determination of specific human pituitary cells and as a paracrine or autocrine regulator of mature ACTH.

Antibody constant region: potential to bind metal and nucleic acid

Environmental challenges appear to elicit similar patterns of cellular responses such as positive autoregulation and autoamplification whether one considers the generation of antibodies with identical antigen specificity or the accumulation of host-protective transcription factors. Therefore, I analyzed the structure of immunoglobulins (Ig) for motifs commonly found in transcription factors. Specifically, the well-known abundance and periodic location of cysteine residues in immunoglobulin chains prompted me to check antibody constant regions for the presence of putative metal-binding domains and zinc finger-like sequences. The constant regions of Ig light and heavy chains were found to harbor one or several copies, respectively, of a short cysteine- and histidine-containing sequence. Moreover, all four IgG subclasses were detected to comprise zinc finger-like motifs in their heavy chain constant and hinge domains. Yet another finding is the occurrence of several sequences of the form serine-proline-X-X and/or threonine-proline-X-X in the hinge sections of IgA and IgG3. These results suggest that antibody constant regions, as a fragment and/or embedded in a full-length immunoglobulin chain, may complex metal, thus acquiring conformations conducive to dimerization and nucleic acid binding. As such, my study provides a putative structural basis for the known requirement of divalent metal cations, particularly of zinc ions, for a normal immune response, and warrants further investigations, both theoretical and experimental, into the potential of antibody constant regions for metal binding and gene regulation. Moreover, future testing of the proposed zinc finger peptides from Ig constant domains should yield information relevant to zinc finger design with potentially wide applications in research and clinical medicine.(ABSTRACT TRUNCATED AT 250 WORDS)

A dysbalanced immune system in cryptogenic Lennox-Gastaut syndrome

In children with cryptogenic Lennox-Gastaut syndrome we found a functionally impaired humoral immune response to a primary antigen (haemocyanin), despite signs of a triggered immune system consisting of elevated IgG concentrations. This combination of immunological findings, considered to be the expression of a dysbalanced-triggered as well as functionally impaired-immune system, has also been described in an auto-immune disease like systemic lupus erythaematodes in humans, and in genetically epilepsy-prone rats. The interactions between the immune system and the nervous system in Lennox-Gastaut syndrome will be discussed.

Syndrome of inappropriate secretion of antidiuretic hormone in patients with lymphoma-associated hemophagocytic syndrome

We report three lymphoma patients in whom the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) was observed during the course of lymphoma-associated hemophagocytic syndrome (LAHS). The clinical course was devoid of any known mechanism for SIADH which could be attributable to lymphoma or antineoplastic treatment. Alternatively, high serum levels of interleukin-1 beta and tumor necrosis factor-alpha, which stimulate the secretion of antidiuretic hormone, may have contributed to the development of SIADH in our patients, who were receiving glucocorticoids. In conclusion, LAHS patients should be considered to be at high risk for SIADH.

Alterations in hepatocyte uptake and plasma binding of thyroxine in nonthyroidal illness and caloric deprivation

Low plasma T(3) in severe illness is widely thought to be due principally to inhibition of 5'-deiodinase activity, but other factors also contribute to this response. Abnormal plasma constituents, namely, 3-carboxy-4-methyl-5-propyl-2-furan propanoic acid (CMPF) and indoxyl sulfate in uremia, and elevated bilirubin and nonesterified fatty acids (NEFA) can impair T(4) transport into hepatocytes, thereby contributing to the lowering of plasma T(3). Assessment of possible endogenous or exogenous inhibitors of T(4) binding to plasma proteins is prone to dilution-dependent artifacts, which can lead to overestimation or underestimation of competitor potency, depending on experimental details. Because the potency of such competitors is a function of their free concentrations in undiluted serum, inhibitory activity may be enhanced by substances that impair their albumin binding. Oleic acid or CMPF can inhibit the effect of drugs such as furosemide or fenclofenac.

IL-1 is expressed in human adrenal gland in vivo. Possible role in a local immune-adrenal axis

IL-1 is an important mediator in the dialogue between the immune system and the hypothalamo-pituitary-adrenal axis. A direct influence of IL-1 upon adrenal steroidogenesis has been demonstrated in experimental animals. We therefore designed a study to see if IL-1 is expressed within the normal human adrenal gland. The combination of in situ hybridization and specific immunostaining to IL-1 beta was eminently suited to demonstrate both mRNA and protein production. The specific immunostaining of the different cells combined with in situ hybridization (IL-1) allowed us to identify the exact cellular source of IL-1. IL-1 mRNA occurred in the zona reticularis in 17 alpha-hydroxylase positive steroid cells surrounding the adrenomedullary cells. Some CD68+ macrophages in this zona showed a positive signal. A weak signal was seen to IL-1 mRNA in few chromaffin cells, while IL-1-like immunoreactivity was more frequent. We conclude that in the normal situation in man IL-1 is mainly expressed in specialized cortical cells. The occurrence of the major glucocorticoid inducing factor in the normal human adrenal gland itself provides evidence for an autocrine or paracrine reaction under physiological conditions.

Immunoglobulin treatment in human and experimental epilepsy

The relationship between human immunoglobulin administration, and human and experimental epilepsy was investigated by reviewing the literature as well as the authors' clinical and experimental studies. The focus was: 1) the possible efficacy of IVIg; 2) the possibility that IVIg significantly increases CSF IgG and could reach the brain, and 3) the interaction between the IVIg preparation and epilepsy. There is still no formal proof of efficacy of IVIg treatment in epilepsy. However, the clinical data presented suggests that IVIg is likely to be effective in a subgroup of patients with intractable and epilepsy, and may be considered as a safe add-on medication in various types of idiopathic and symptomatic intractable epilepsy. From the authors' study on cerebrospinal fluid IgG concentrations before and after IVIg treatment in patients with epilepsy, it is concluded that the main component of the IVIg preparation (the IgG molecule) crosses the blood-CSF barrier, significantly increases CSF IgG concentration, and may reach the brain and act centrally. From a review of previous reports and two immunological studies carried out by the authors it is concluded that immunogenetic mechanisms may play a role in triggering or maintaining some types of epilepsy. In view of this, IVIg could act on epilepsy by its broad immunomodulatory mechanism of action. In addition, preliminary data are reported that contribute to the hypothesis that IVIg may have a direct neuromodulating effect.