REVIEW

The combination of abnormally low plasma cystine and glutamine levels, low natural killer (NK) cell activity, skeletal muscle wasting or muscle fatigue, and increased rates of urea production defines a complex of abnormalities that is tentatively called "low CG syndrome." These symptoms are found in patients with HIV infection, cancer, major injuries, sepsis, Crohn's disease, ulcerative colitis, chronic fatigue syndrome, and to some extent in overtrained athletes. The coincidence of these symptoms in diseases of different etiological origin suggests a causal relationship. The low NK cell activity in most cases is not life-threatening, but may be disastrous in HIV infection because it may compromise the initially stable balance between the immune system and virus, and trigger disease progression. This hypothesis is supported by the coincidence observed between the decrease of CD4+ T cells and a decrease in the plasma cystine level. In addition, recent studies revealed important clues about the role of cysteine and glutathione in the development of skeletal muscle wasting. Evidence suggests that 1) the cystine level is regulated primarily by the normal postabsorptive skeletal muscle protein catabolism, 2) the cystine level itself is a physiological regulator of nitrogen balance and body cell mass, 3) the cyst(e)ine-mediated regulatory circuit is compromised in various catabolic conditions, including old age, and 4) cysteine supplementation may be a useful therapy if combined with disease- specific treatments such as antiviral therapy in HIV infection.

Clinical Improvement in Chronic Fatigue Syndrome Is Associated with Enhanced Natural Killer Cell-Mediated Cytotoxicity: The Results of a Pilot Study with Isoprinosine® Francisco Diaz-Mitoma MD, PhD, FRCP(C), Chief and Professor, Children's Hospital of Eastern Ontario, Ottawa, ON, K1H 8L1, Canada, K1H 8L1 Eva Turgonyi MD, Newport Pharmaceuticals Ltd., Franz Maas House Swords Business Park, Swoards, Co., Dublin, Ireland Ashok Kumar PhD, Children's Hospital of Eastern Ontario, Ottawa, ON, K1H 8L1, Canada Wilfred Lim, Division of Virology, Children's Hospital of Eastern Ontario, Ottawa, ON, K1H 8L1, Canada Louise Larocque, Division of Virology, Children's Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, ON, K1H 8L1, Canada Byron M. Hyde MD, The Nightingale Research Foundation, 121 Iona Street. Ottawa, Canada K1Y 3M1

Abstract: Chronic fatigue syndrome is associated with systemic and cognitive symptoms and with several immune abnormalities. The clinical impact of Isoprinosine® was evaluated in sixteen CFS patients, followed for 28 weeks in a single-blind, placebo controlled trial. Patients were also monitored for various immune parameters. Improvement based on clinical staging was observed in six of ten treated patients (60%). Clinically improved patients showed significantly enhanced natural killer (NK) cell activity, which correlated with the duration of Isoprinosine treatment (p < 0.03). Treatment with Isoprinosine resulted in significantly increased numbers of CD4+ T helper cells (p < 0.03). Treatment with Isoprinosine for 12 weeks did not appreciably influence the in vitro production of IFN-y, IL-1á, IL-10 or IL-12. However, IL-12 was significantly increased at week 28 (p < 0.02) in patients who improved after treatment with Isoprinosine. These results suggest that taking Isoprinosine may benefit a subgroup of patients with CFS, and this clinical improvement is associated with enhanced NK cell function and IL-12 levels. Further trials to evaluate the use of Isoprinosine in the treatment of CFS patients are warranted

Monitoring a Hypothetical Channelopathy in Chronic Fatigue Syndrome: Preliminary Observations Journal of Chronic Fatigue Syndrome: Multidisciplinary Innovations in Research, Theory, and Clinical Practice Jo Nijs MSc, Department of Human Physiology, Faculty of Physica Christian Demanet MD, PhD, Division of Hematology and Immunology, Academic Ho Neil R. McGregor BDS, MDSc, PhD, Collaborative Pain Research Unit, Departmentof Bio Pascale De Becker, Department of Human Physiology, Faculty of Physica Michel Verhas MD, PhD Patrick Englebienne PhD Kenny De Meirleir MD PhD, Department of Human Physiology Volume: 11 Issue: 1 ISSN: 1057-3321 Pub Date: 1/23/2003

Abstract: This study was aimed at monitoring of a previously suggested channelopathy in Chronic Fatigue Syndrome, and at searching for possible explanations by means of immune system characteristics. Twenty-seven CFS patients and 20 age and sex matched healthy volunteers were recruited. RNase L-ratio, percent of the norm of whole body potassium content, serum electrolytes (sodium, calcium and potassium), immune cells, blood cell count and erythrocyte sedimentation rate were determined. More than fifty percent of our patients presented with abnormal whole body potassium content. Eight patients had increased, while six had depleted potassium content. Discriminant function analysis revealed that the CFS patients and control subjects could be differentiated on immunophenotyping with the predominant cell differences being the increase in CD19+ CD5+ (mature B-) cells and the decrease in CD3CD16+ CD56+ (NK) cells in both the percentage and count distributions. The fall in NK-cells was very strongly associated with increases in the RNase L-ratio and falls in serum calcium levels. In addition, four patients with low serum calcium levels showed lower whole body potassium levels. In conclusion, these observations suggest a channelopathy in a subset of CFS patients, probably induced by the deregulated 2-5A RNase L antiviral pathway

Neuroimmune mechanisms in health and disease: Part 2. Anisman H, Baines MG, Berczi I, Bernstein CN, Blennerhassett MG, Gorczynski RM. Canadian Medical Association Journal 1996; 155(8): 1075-82.

Abstract: In the second part of their article on the emerging field of neuroimmunology, the authors present an overview of the role of neuroimmune mechanisms in defence against infectious diseases and in immune disorders. During acute febrile illness, immune-derived cytokines initiate an acute phase response, which is characterized by fever, inactivity, fatigue, anorexia and catabolism. Profound neuroendocrine and metabolic changes take place: acute phase proteins are produced in the liver, bone marrow function and the metabolic activity of leukocytes are greatly increased, and specific immune reactivity is suppressed. Defects in regulatory processes, which are fundamental to immune disorders and inflammatory diseases, may lie in the immune system, the neuro endocrine system or both. Defects in the hypothalamus-pituitary-adrenal axis have been observed in autoimmune and rheumatic diseases, chronic inflammatory disease, chronic fatigue syndrome and fibromyalgia. Prolactin levels are often elevated in patients with systemic lupus erythematosus and other autoimmune diseases, whereas the bioactivity of prolactin is decreased in patients with rheumatoid arthritis. Levels of sex hormones and thyroid hormone are decreased during severe inflammatory disease. Defective neural regulation of inflammation likely plays a pathogenic role in allergy and asthma, in the symmetrical form of rheumatoid arthritis and in gastrointestinal inflammatory disease. A better understanding of neuroimmunoregulation holds the promise of new approaches to the treatment of immune and inflammatory diseases with the use of hormones, neurotransmitters, neuropeptides and drugs that modulate these newly recognized immune regulators.

Low NK syndrome and its relationship to chronic fatigue syndrome. Aoki T, Miyakoshi H, Usuda Y, Herberman RB. Clinical Immunology and Immunopathology 1993; 69(3): 253-65.

Immunologic abnormalities associated with chronic fatigue syndrome. Barker E, Fujimura SF, Fadem MB, Landay AL, Levy JA. Clinical Infectious Diseases 1994; 18(Supp 1): S136-41.

Abstract: Several aspects of cellular immunity in patients with clinically defined chronic fatigue syndrome (CFS) were evaluated and compared with those in healthy individuals. Flow cytometric analyses revealed normal expression of total T (CD3+), B (CD19+), and NK (natural killer) (CD16+, CD56+) markers on the surface of peripheral blood mononuclear cells (PMC) from patients with CFS. However, compared with those of healthy individuals, patients' CD8+ T cells expressed reduced levels of CD11b and expressed the activation markers CD38 and HLA-DR at elevated levels. In many of the individuals in whom expression of CD11b was reduced the expression of CD28 was increased. These findings indicate expansion of a population of activated CD8+ cytotoxic T lymphocytes. A marked decrease in NK cell activity was found in almost all patients with CFS, as compared with that in healthy individuals. No substantial abnormalities in monocyte activity or T cell proliferation were observed. The results of this study suggest that immune cell phenotype changes and NK cell dysfunction are common manifestations of CFS.

The postviral fatigue syndrome - an analysis of the findings in 50 cases. Behan PO, et al. Journal of Infection 1985; 10: 211-22.

Abstract: The clinical, pathological, electrophysiological, immunological and virological abnormalities in 50 patients with the postviral fatigue syndrome are recorded. These findings confirm the organic nature of the disease. A metabolic disorder, caused by persistent virus infection and associated with defective immunoregulation, is suggested as the pathogenetic mechanism.

A chronic illness characterized by fatigue, neurologic and immunologic disorders, and active human herpesvirus type 6 infection. Buchwald D, Cheney PR, Peterson DL, Henry B, Wormsley SB, Geiger A, Ablashi DV, Salahuddin SZ, Saxinger C, Biddle R, et al. Annals of Internal Medicine 1992; 116(2): 103-13.

Abstract: OBJECTIVE: To conduct neurologic, immunologic, and virologic studies in patients with a chronic debilitating illness of acute onset. DESIGN: Cohort study with comparison to matched, healthy control subjects. PATIENTS: We studied 259 patients who sought care in one medical practice; 29% of the patients were regularly bedridden or shut-in. MAIN OUTCOME MEASURES: Detailed medical history, physical examination, conventional hematologic and chemistry testing, magnetic resonance imaging (MRI) studies, lymphocyte phenotyping studies, and assays for active infection of patients' lymphocytes with human herpesvirus type 6 (HHV-6). MAIN RESULTS: Patients had a higher mean (± SD) CD4/CD8 T-cell ratio than matched healthy controls (3.16 ± 1.5 compared with 2.3 ± 1.0, respectively; P less than 0.003). Magnetic resonance scans of the brain showed punctate, subcortical areas of high signal intensity consistent with edema or demyelination in 78% of patients (95% CI, 72% to 86%) and in 21% of controls (CI, 11% to 36%) (P less than 10(-9)). Primary cell culture of lymphocytes showed active replication of HHV-6 in 79 of 113 patients (70%; CI, 61% to 78%) and in 8 of 40 controls (20%; CI, 9% to 36%) (P less than 10(-8], a finding confirmed by assays using monoclonal antibodies specific for HHV-6 proteins and by polymerase chain reaction assays specific for HHV-6 DNA. CONCLUSIONS: Neurologic symptoms, MRI findings, and lymphocyte phenotyping studies suggest that the patients may have been experiencing a chronic, immunologically mediated inflammatory process of the central nervous system. The active replication of HHV-6 most likely represents reactivation of latent infection, perhaps due to immunologic dysfunction. Our study did not directly address whether HHV-6, a lymphotropic and gliotropic virus, plays a role in producing the symptoms or the immunologic and neurologic dysfunction seen in this illness. Whether the findings in our patients, who came from a relatively small geographic area, will be generalizable to other patients with a similar syndrome remains to be seen.

A Chronic "postinfectious" fatigue syndrome associated with benign lymphoproliferation, B-cell proliferation, and active replication of human herpesvirus-6. Buchwald D, Freedman AS, Ablashi DV, Sullivan JL, Caligiuri M, Weinberg DS, Hall CG, Ashley RL, Saxinger C, Balachandran N, Ritz J, Nadler LM, Komaroff AL. Journal of Clinical Immunology 1990; 10(6): 335-343.

Abstract: A 17-year-old, previously healthy woman developed an acute "mononucleosis-like" illness with an associated "atypical" pneumonitis, followed by years of debilitating chronic fatigue, fevers, a 10-kg weight loss, night sweats, and neurocognitive symptoms. Thereafter, her sister developed a similar but less severe illness. The patient developed marked, chronic lymphadenopathy and splenomegaly, with associated persistent relative lymphocytosis and atypical lymphocytosis and with thrombocytopenia. After 3 years of illness, a splenectomy was performed, which resulted in some symptomatic improvement, prompt weight gain, and resolution of all hematologic abnormalities. Serial immunologic studies revealed a strikingly elevated number of activated B lymphocytes and a T lymphopenia, which improved but did not return to normal postsplenectomy. No causal association was found with any of several infectious agents that could produce such a lymphoproliferative illness. However, both the patient and her sister had evidence of active infection with the recently discovered human herpesvirus-6. Seven years after the onset of the illness, the patient and her sister remain chronically ill.

Review of laboratory findings for patients with chronic fatigue syndrome. Buchwald D, Komaroff AL. Reviews of Infectious Diseases 1991; 13(Suppl 1): S12-S28.

Abstract: Various abnormalities revealed by laboratory studies have been reported in adults with chronic fatigue syndrome. Those most consistently reported include depressed natural killer cell function and reduced numbers of natural killer cells; low levels of circulating immune complexes; low levels of several autoantibodies, particularly antinuclear antibodies and antithyroid antibodies; altered levels of immunoglobulins; abnormalities in number and function of lymphocytes; and modestly elevated levels of two Epstein-Barr virus-related antibodies, immunoglobulin G to viral capsid antigen and to early antigen.

Eosinophil cationic protein serum levels and allergy in chronic fatigue syndrome. Conti F, Magrini L, Priori R, Valesini G, Bonini S. Allergy 1996: 51: 124-7.

Abstract: Chronic fatigue syndrome (CFS) is a syndrome of uncertain etiopathogenesis characterized by disabling fatigue associated with a variable number of somatic and/or neuropsychologic symptoms. In patients with CFS, several immunologic abnormalities can be detected, including a higher prevalance of allergy. The aim of this study was to determine whether CFS patients, well studied for their allergy profile, show signs of eosinophil activation, as detectable by the measurement in serum of eosinophil cationic protein (ECP) levels. In 35 consecutive CFS outpatients (diagnosis based on the Centers for Disease Control case definition), ECP was measured in serum by a competitive enzyme immunoassay (ECP-FEIA kit, Kabi Pharmacia Diagnostics, Uppsala, Sweden). Fourteen disease-free subjects with no history of CFS or allergy were selected as controls. ECP serum levels were significantly higher in CFS patients than in controls (18.0 ± 11.3 micrograms/l vs 7.3 ± 2.1 micrograms/l; P < 0.01). In the CFS population, the prevalence of RAST positivity to one or more allergens was 77%, while no control showed positive RAST. Twelve of the 14 CFS patients with increased ECP serum levels were RAST-positive. However, CFS RAST-positive patients had no significantly higher ECP serum levels than CFS RAST-negative patients (19.3 ± 12.4 micrograms/l vs 13.6 ± 3.7 micrograms/l; P="0.4)." This is the first report of increased serum levels of ECP in CFS. On the basis of the available data, it is discussed whether eosinophil activation has a pathogenetic role in CFS or is linked to the frequently associated allergic condition, or, finally, whether a common immunologic background may exist for both atopy and CFS.

Chronic fatigue syndrome - immunological findings vary between populations [Letter]. Abbot NC, Spence VA, Lowe JG, Potts RC, Hassan AH, Belch JJ, Beck JS. British Medical Journal 1994; 308: 1299.

Low serum b2 - microglobulin levels in CFS patients De Becker P, De Meirleir K, Demanet C, Wets L, Joos E, Smitz J. Journal of Chronic Fatigue Syndrome 1996; 2(2/3): 106.

Abstract: OBJECTIVE: Elevations of serum b2-Microglobulin (b2m) have been described in patients with a variety of illnesses, including malignancies, acquired immune deficiency syndrome and rheumatic disease. A low molecular weight polypeptide synthesized by all nucleated cells of the body, b2m forms part of the HLA class I antigens on the cell membrane. Because abnormalities of both humoral and cellular immunity have been demonstrated in a substantial proportion of patients with CFS, we measured serum b2m and compared it to those of matched controls. METHODS. From our outpatient clinic we recruited 18 patients (mean age ± SD; 34.8 ± 6.49) who met the CDC criteria for CFS. All patients had been investigated to exclude alternative medical diagnosis. Controls were 14 age- and sex-matched healthy individuals (mean age ± SD; 34.7 ± 7.25); all were free of major medical or psychiatric diseases. Data were analyzed by using Student's t-test; a p value < 0.01 was considered statistically significant. RESULTS. Mean b2 microglobulin levels of CFS-patients ± SD="0.981" UG/L ± 0.123; mean b2 microglobulin levels of matched controls ± SD="1.179" ± 0.246 (p="0.0012)." CONCLUSION. Our data show that CFS patients have lower serum b2 microglobulin levels compared to controls. Although this is not a diagnostical marker, it adds to the numerous disturbances observed in the immunity of CFS patients.

A comprehensive immunological analysis in chronic fatigue syndrome. Gupta S, Vayuvegula B. Scandinavian Journal of Immunology 1991; 33: 319-327.

Abstract: A detailed analysis of cell-mediated and antibody-mediated immunity was performed in 20 CDC-defined patients with chronic fatigue syndrome (CFS) and 20 age- and sex-matched healthy controls. CD3+, CD4+, CD8+, and CD20+ lymphocytes were comparable in two groups. Natural killer cells as defined by CD16, CD56 and CD57 antigens were significantly reduced in CFS. A significant increase in the proportions of CD4+ ICAM 1+ T cells was observed in CFS. Monocytes from CFS displayed increased density (as determined by mean fluorescence channel numbers) of intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function associated antigen 1 (LFA-1), but showed decreased enhancing response to recombinant interferon-gamma in vitro. The lymphocyte DNA synthesis in response to phytohaemoglobulin (PHA), Concanavalin A (Con A) and pokeweed mitogen (PWM) was normal but the response to soluble antigens was significantly reduced. Serum IgM, IgG, IgA, and IgG subclasses were normal. In vivo specific antibody response to pneumococcus vaccine was depressed in CFS. Forty percent of patients showed titres of anti-human herpes virus 6 (anti-HHV-6) antibody higher than that in the controls (greater than or equal to 1/80). These data suggest immunological dysfunction in patients with chronic fatigue syndrome. The significance of these observations is discussed.