Autoreactive T and B cell responses to myelin antigens after diagnostic sural nerve biopsy

Associations of cells from both innate and adaptive immunity with lower nerve conduction velocity: the Maastricht Study

INTRODUCTION

Distal sensorimotor polyneuropathy (DSPN) is common in people with diabetes but is also found in pre-diabetes. Peripheral nerve myelin damage, which can be assessed by reduced nerve conduction velocity (NCV), is an essential feature of DSPN. Emerging evidence indicates that the development of DSPN may involve the activation of the immune system. However, available studies have mainly investigated circulating immune mediators, whereas the role of immune cells remains unclear. Therefore, we aimed to test whether leukocyte subsets are associated with NCV.

RESEARCH DESIGN AND METHODS

This cross-sectional study analyzed data from 850 individuals (of whom 252 and 118 had type 2 diabetes and pre-diabetes, respectively) of the Maastricht Study. NCV was measured in the peroneal and tibial motor nerves and the sural sensory nerve and summed to calculate a standardized NCV sum score. Associations between percentages of leukocyte subsets and NCV sum scores were estimated using linear regression models adjusted for demographic, lifestyle, metabolic and clinical covariates.

RESULTS

After adjustment for covariates, higher percentages of basophils and CD4⁺ T cells were associated with lower NCV (p=0.014 and p=0.005, respectively). The percentage of CD8⁺ T cells was positively associated with NCV (p=0.022). These associations were not modified by glucose metabolism status (all p_interaction >0.05). No associations were found for monocytes, eosinophils, neutrophils, lymphocytes, total T cells, Treg cells and B cells.

CONCLUSIONS

The associations of basophils, CD4⁺ and CD8⁺ T cells with NCV suggest that cell types from both innate and adaptive immunity may be implicated in the development of DSPN.

Synergistic Activation of Toll-Like and NOD Receptors by Complementary Antigens as Facilitators of Autoimmune Disease: Review, Model and Novel Predictions

Persistent activation of toll-like receptors (TLR) and nucleotide-binding oligomerization domain-containing proteins (NOD) in the innate immune system is one necessary driver of autoimmune disease (AD), but its mechanism remains obscure. This study compares and contrasts TLR and NOD activation profiles for four AD (autoimmune myocarditis, myasthenia gravis, multiple sclerosis and rheumatoid arthritis) and their animal models. The failure of current AD theories to explain the disparate TLR/NOD profiles in AD is reviewed and a novel model is presented that explains innate immune support of persistent chronic inflammation in terms of unique combinations of complementary AD-specific antigens stimulating synergistic TLRs and/or NODs. The potential explanatory power of the model is explored through testable, novel predictions concerning TLR- and NOD-related AD animal models and therapies.

Implications of immunotherapy with high-dose glatiramer acetate in acute phase of spinal cord injury in rats

Objective: Recently, many researches with different viewpoints have focused on application of immunotherapy agents in treatment of spinal cord injury (SCI) according to neuroprotective results in some neurodegenerative disease. Glatiramer acetate (GA) is the most commonly used drug for Multiple sclerosis (MS) patients that exerts an immunomodulatory effect against Myelin basic protein (MBP) antigen. Materials and methods: High-dose (2mg/kg) treatment of GA for 28 consecutive days after SCI was compared with its low-dose (0.5 mg/kg) treatment, SCI control and Sham control rat groups. Results: High-dose GA group had significantly worsened outcome in standard functional recovery evaluation test (BBB) 12 weeks after SCI compared to SCI control and low-dose GA groups, which was confirmed by augmented spinal cavity volume and reduced ventral horn motor neurons in high-dose GA group; however, there was no significant difference between low-dose GA and control SCI group. In addition, proliferation test performed on lymphocytes from spleen and lymph nodes one week after SCI showed that high-dose GA injection has more significant effect on Division Index (DI) in response to MBP stimulation compared to low-dose GA and control SCI groups, which was associated with significant increase in IFN-γ, IL-4, and IL-17A secretion. Conclusion: Along with confirmation of deleterious aspects of autoimmunity resulting from autoreactive lymphocytes against myelin antigens in SCI, this study has shown that high-dose immunotherapy using GA, especially in acute phase after SCI, overwhelms any neuroprotective effect of adoptive immune system.

Lymphocytes and autoimmunity after spinal cord injury

Over the past 15 years an immense amount of data has accumulated regarding the infiltration and activation of lymphocytes in the traumatized spinal cord. Although the impact of the intraspinal accumulation of lymphocytes is still unclear, modulation of the adaptive immune response via active and passive vaccination is being evaluated for its preclinical efficacy in improving the outcome for spinal-injured individuals. The complexity of the interaction between the nervous and the immune systems is highlighted in the contradictions that appear in response to these modulations. Current evidence regarding augmentation and inhibition of the adaptive immune response to spinal cord injury is reviewed with an aim toward reconciling conflicting data and providing consensus issues that may be exploited in future therapies. Opportunities such an approach may provide are highlighted as well as the obstacles that must be overcome before such approaches can be translated into clinical trials.

Both MHC and non-MHC genes regulate inflammation and T-cell response after traumatic brain injury

Genetic regulation of autoimmune neuroinflammation is a well known phenomenon, but genetic influences on inflammation following traumatic nerve injuries have received little attention. In this study we examined the inflammatory response in a rat traumatic brain injury (TBI) model, with a particular focus on major histocompatibility class II (MHC II) presentation, in two inbred rat strains that have been extensively characterized in experimental autoimmune encephalomyelitis (EAE); DA and PVG. In addition, MHC and Vra4 congenic strains on these backgrounds were studied to give information on MHC and non-MHC gene contribution. Thus, allelic differences in Vra4, harboring the Ciita gene, was found to regulate expression of the invariant chain at the mRNA level, with a much smaller effect exerted by the MHC locus itself. Notably, however, at the protein level the MHC congenic PVG-RT1(av1) strain displayed much stronger MHCII(+) presentation, as shown both by immunolabeling and flow cytometry, than the PVG strain, dwarfing the effect of Ciita. The PVG-RT1(av1) strain had significantly more T-cell influx than both DA and PVG, suggesting regulation both by MHC and non-MHC genes. Finally, in terms of outcome, the EAE susceptible DA strain displayed a significantly smaller resulting lesion volume than the resistant PVG-RT1(av1) strain. These results provide additional support for a role of adaptive immune response after neurotrauma and demonstrate that outcome is significantly affected by host genetic factors.

Protective autoimmunity in the nervous system

The immune system can play both detrimental and beneficial roles in the nervous system. Multiple arms of the immune system, including T cells, B cells, NK cells, mast cells, macrophages, dendritic cells, microglia, antibodies, complement and cytokines participate in limiting damage to the nervous system during toxic, ischemic, hemorrhagic, infective, degenerative, metabolic and immune-mediated insults and also assist in the process of repair after injury has occurred. Immune cells have been shown to produce neurotrophic growth factors and interact with neurons and glial cells to preserve them from injury and stimulate growth and repair. The immune system also appears to participate in proliferation of neural progenitor stem cells and their migration to sites of injury. Neural stem cells can also modify the immune response in the central and peripheral nervous system to enhance neuroprotective effects. Evidence for protective and reparative functions of the immune system has been found in diverse neurologic diseases including traumatic injury, ischemic and hemorrhagic stroke, multiple sclerosis, infection, and neurodegenerative diseases (Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis). Existing therapies including glatiramer acetate, interferon-beta and immunoglobulin have been shown to augment the protective and regenerative aspects of the immune system in humans, and other experimental interventions such as vaccination, minocycline, antibodies and neural stem cells, have shown promise in animal models of disease. The beneficent aspects of the immune response in the nervous system are beginning to be appreciated and their potential as pharmacologic targets in neurologic disease is being explored.

Leukemia inhibitory factor is produced by myelin-reactive T cells from multiple sclerosis patients and protects against tumor necrosis factor-α-induced oligodendrocyte apoptosis

In multiple sclerosis (MS), damage to oligodendrocytes is believed to be caused by an aberrant immune response initiated by autoreactive T cells. Increasing evidence indicates that these T cells are not exclusively detrimental but might also exert protective effects. We report for the first time that myelin-reactive T-cell clones from eight MS patients (6/19) and five healthy controls (4/11) produce leukemia inhibitory factor (LIF), a member of the neuropoietic family of neurotrophins. In addition, T-cell clones specific for tetanus toxoid, CD4(+) and CD8(+) T cells, and monocytes, but not B cells, secreted LIF. LIF-producing T lymphocytes and macrophages were also identified immunohistochemically in both active and chronic-active MS lesions. We further demonstrated dose-dependent protective effects of LIF on tumor necrosis factor-alpha-induced apoptosis of oligodendrocytes. In conclusion, our data demonstrate that peripheral and CNS-infiltrating T cells from MS patients produce LIF, a protective factor for oligodendrocytes. This study emphasizes that secretion of LIF may contribute to the neuroprotective effects of autoreactive T cells.

Passive or active immunization with myelin basic protein impairs neurological function and exacerbates neuropathology after spinal cord injury in rats

Myelin-reactive T-cells are activated by traumatic spinal cord injury (SCI) in rodents and humans. Despite the historical association of these cells with experimental and clinical neuropathology, recent data suggest a neuroprotective role for myelin-reactive T-cells. Because of the biological and therapeutic implications of these findings, we attempted to reproduce the original neuroprotective vaccine protocols in a model of rat SCI. Specifically, MBP-reactive T-cell function was enhanced in SCI rats via passive or active immunization. Locomotor function was assessed using a standardized locomotor rating scale (Basso-Beattie-Bresnahan scale) and was correlated with myelin and axon sparing. The functional and anatomical integrity of the rubrospinal pathway also was analyzed using the inclined plane test and anatomical tract tracing. MBP-immunized rats exhibited varying degrees of functional impairment, exacerbated lesion pathology, greater rubrospinal neuron loss, increased intraspinal T-cell accumulation, and enhanced macrophage activation relative to SCI control groups. These data are consistent with the conventional view of myelin-reactive T-cells as pathological effector cells.

Manipulating neuroinflammatory reactions in the injured spinal cord: back to basics

Recruitment of inflammatory leukocytes to the injured spinal cord is a physiological response that is associated with the production of cytokines and proteinases that are involved in host defense and wound repair. Cells in the spinal cord are mainly post-mitotic and tissue regeneration is poor; thus, these inflammatory mediators can exacerbate the damage to spared tissue and thereby impair spontaneous functional recovery. Although several aspects of immune function might benefit the CNS, experimental studies indicate that acute neuroinflammation aggravates tissue injury. Until the timing and nature of the molecular signals that govern leukocyte recruitment and activation after spinal injury are defined, clinical therapies designed to boost immune cell function should be avoided.

Contralateral non-operated nerve to transected rat sciatic nerve shows increased expression of IL-1beta, TGF-beta1, TNF-alpha, and IL-10

Recent reports indicate that after a peripheral nerve injury, the uninjured contralateral nerve is also affected. Because cytokines play an important role in the peripheral nerve injury, we studied the expression of five different mRNAs (interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10), transforming growth factor-beta1 (TGF-beta1) and interleukin-4 (IL-4)) in the contralateral, non-operated, left sciatic nerve when the right rat sciatic nerve was transected. This study extended up to 42 days after the transection. No IL-4 expression was noted. During the first 3 days, high expression of the other studied cytokines was noted in the endoneurium. At day 7, the expression diminished to the control levels. After this, a cyclic expression pattern appeared, which was most pronounced in the endoneurium at 35 days. We also show that the expression pattern in the endoneurium is different from that in the surrounding epi- and perineurium. Also, our present study shows clearly that contralateral nerves are poor controls after injury.

Multiple MAG peptides are recognized by circulating T and B lymphocytes in polyneuropathy and multiple sclerosis

Abnormal immune responses to myelin associated glycoprotein (MAG), a component of myelin of the central and peripheral nervous system, have been suggested to play a role in the pathogenesis of multiple sclerosis (MS) and certain types of inflammatory polyneuropathy. To identify possible immunodominant MAG peptides in neuroinflammation, we examined T and B cell responses to five selected synthetic MAG peptides and myelin proteins in 21 patients with non-inflammatory polyneuropathy, 26 patients with MS, 10 optic neuritis patients and 17 healthy subjects. Enzyme-linked immunosorbent spot-forming cell assays were adopted, allowing the detection and enumeration of individual antigen responsive T and B cells in body fluids. Patients with polyneuropathy as well as those with MS had elevated levels of T and B cells recognizing MAG and its peptides. Any of the five MAG peptides under study functioned as immunodominant T and/or B cell epitope in individual subjects. None of the MAG peptides elicited a specific disease-associated T or B cell response. The enhanced T and B cell response to myelin components like MAG may play some role in initiation and/or progression of these diseases, but they could also represent secondary responses associated with myelin damage and indicate tolerization rather than autoaggressive immunity.

Pathological CNS autoimmune disease triggered by traumatic spinal cord injury: implications for autoimmune vaccine therapy

Lymphocytes respond to myelin proteins after spinal cord injury (SCI) and may contribute to post-traumatic secondary degeneration. However, there is increasing evidence that autoreactive T-lymphocytes may also convey neuroprotection and promote functional recovery after CNS injury. To clarify the role of myelin autoreactive lymphocytes after SCI, we performed contusion injuries in the thoracic spinal cord of transgenic (Tg) mice in which >95% of all CD4+ T-lymphocytes are reactive with myelin basic protein (MBP). We observed significantly impaired recovery of locomotor and reflex function in Tg mice compared with non-Tg (nTg) littermates. Measures of functional impairment in Tg mice correlated with significantly less white matter at the injury site, and morphometric comparisons of injured Tg and nTg spinal cords revealed increased rostrocaudal lesion expansion (i.e., secondary degeneration) in Tg mice. Rostrocaudal to the impact site in SCI-nTg mice, demyelination was restricted to the dorsal funiculus, i.e., axons undergoing Wallerian degeneration. The remaining white matter appeared normal. In contrast, lymphocytes were colocalized with regions of demyelination and axon loss throughout the white matter of SCI-Tg mice. Impaired neurological function and exacerbated neuropathology in SCI-Tg mice were associated with increased intraspinal production of proinflammatory cytokine mRNA; neurotrophin mRNA was not elevated. These data suggest that endogenous MBP-reactive lymphocytes, activated by traumatic SCI, can contribute to tissue injury and impair functional recovery. Any neuroprotection afforded by myelin-reactive T-cells is likely to be an indirect effect mediated by other non-CNS-reactive lymphocytes. Similar to the Tg mice in this study, a subset of humans that are genetically predisposed to autoimmune diseases of the CNS may be adversely affected by vaccine therapies designed to boost autoreactive lymphocyte responses after CNS trauma. Consequently, the safe implementation of such therapies requires that future studies define the mechanisms that control T-cell function within the injured CNS.

Differential expression of neurotrophic factors and inflammatory cytokines by myelin basic protein-specific and other recruited T cells infiltrating the central nervous system during experimental autoimmune encephalomyelitis

Recent evidence suggests that autoimmune reactions in the central nervous system (CNS) not only have detrimental consequences but can also be neuroprotective, and that this effect is mediated by the expression of neuronal growth factors by infiltrating leucocytes. Here we dissect these two phenomena in guinea pig myelin basic protein peptide (gpMBP 63-88)-induced experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. Real-time TaqMan polymerase chain reaction (PCR) was used to measure mRNA for the nerve growth factors, brain-derived neurotrophic factor (BDNF) and neurotrophin (NT)-3. As reference, the well-known proinflammatory mediator molecules interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha were quantified. In whole lumbar cord tissue, both the nerve growth factors and the proinflammatory cytokines, IFN-gamma and TNF-alpha, displayed similar expression patterns, peaking at the height of the disease. Among the infiltrating inflammatory cells isolated and sorted from the CNS, alphabeta+/T-cell receptor (TCR)BV8S2+, but not alphabeta+/TCRBV8S2-, recognized the encephalitogenic MBP peptide. Interestingly, these two populations displayed contrasting expression patterns of nerve growth factors and proinflammatory cytokines with higher inflammatory cytokine mRNA levels in alphabeta+/TCRBV8S2+ cells at all time intervals, whereas the levels of BDNF and NT3 were higher in alphabeta+/TCRBV8S2- cells. We conclude that a potentially important neuroprotective facet of CNS inflammation dominantly prevails within other non-MBP peptide-specific lymphoid cells and that there are independent regulatory mechanisms for neurotrophin and inflammatory cytokine expression during EAE.

The pathogenesis of multiple sclerosis: a commentary

A series of recently published articles by a group of Austrian, German and American neuropathologists have proposed the existence of several different pathogenetic pathways in multiple sclerosis (MS). These studies were based on both biopsy and autopsy material. A review of the available published clinical, imaging and cerebrospinal fluid data suggest that some the cases used in those studies were more probably instances of disseminated encephalomyelitis rather than MS. This has serious implications regarding the specificity and significance of the findings in regard to MS pathogenesis. The specific myelinoclastic sequence and the variable clinical course of MS are determined by the individual's genetic endowment and immunologic history. Regardless of pathogenetic pathway and clinical course, the final pathologic picture of MS is always the same. The MS brain is genetically programmed to produce a unique, pathognomonic change, the plaque with sharply demarcated borders.

Neuroprotection by encephalomyelitis: rescue of mechanically injured neurons and neurotrophin production by CNS-infiltrating T and natural killer cells

In experimental autoimmune encephalomyelitis (EAE), CD4(+) self-reactive T cells target myelin components of the CNS. However, the consequences of an autoaggressive T cell response against myelin for neurons are currently unknown. We herein demonstrate that EAE induced by active immunization with an encephalitogenic myelin basic protein peptide dramatically reduces the loss of spinal motoneurons after ventral root avulsion in rats. Both brain-derived neurotophic factor (BDNF)- and neurotrophin-3 (NT-3)-like immunoreactivities were detected in mainly T and natural killer (NK) cells in the spinal cord. In addition, very high levels of BDNF, NT-3, and glial cell line-derived neurotrophic factor mRNAs were present in T and NK cell populations infiltrating the CNS. Interestingly, bystander recruited NK and T cells displayed similar or higher neurotrophic factor levels compared with the EAE disease-driving encephalitogenic T cell population. High levels of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) mRNAs were also detected, and both these cytokines can be harmful to several types of CNS cells, including neurons. However, treatment of embryonic motoneuron cultures with TNF-alpha or IFN-gamma only had a deleterious effect in cultures deprived of neurotrophic factors. These results suggest that the potentially neurodamaging consequences of severe CNS inflammation are curbed by the production of several potent neurotrophic factors in leukocytes.

Antibodies against the myelin oligodendrocyte glycoprotein and the myelin basic protein in multiple sclerosis and other neurological diseases: a comparative study

In experimental animal models of multiple sclerosis demyelinating antibody responses are directed against the myelin oligodendrocyte glycoprotein (MOG). We have investigated whether a similar antibody response is also present in multiple sclerosis patients. Using the recombinant human extracellular immunoglobulin domain of MOG (MOG-Ig) we have screened the sera and CSFs of 130 multiple sclerosis patients, 32 patients with other inflammatory neurological diseases (OIND), 30 patients with other non-inflammatory neurological diseases (ONND) and 10 patients with rheumatoid arthritis. We report that 38% of multiple sclerosis patients are seropositive for IgG antibodies to MOG-Ig compared with 28% seropositive for anti-myelin basic protein (MBP). In contrast, OIND are characterized by similar frequencies of serum IgG antibody responses to MOG-Ig (53%) and MBP (47%), whereas serum IgG responses to MOG-Ig are rare in ONND (3%) and rheumatoid arthritis (10%). Anti-MBP IgG antibodies, however, are a frequent finding in ONND (23%) and rheumatoid arthritis (60%). Our results provide clear evidence that anti-MOG-Ig antibodies are common in CNS inflammation. However, in OIND these antibody responses are transient, whereas they persist in multiple sclerosis. We demonstrate that the serum anti-MOG-Ig response is already established in early multiple sclerosis (multiple sclerosis-R0; 36%). In later multiple sclerosis stages frequencies and titres are comparable with early multiple sclerosis. In contrast, the frequency of anti-MBP antibodies is low in multiple sclerosis-R0 (12%) and increases during disease progression in relapsing-remitting (32%) and chronic progressive multiple sclerosis (40%), thus suggesting that anti-MBP responses accumulate over time. Finally we provide evidence for intrathecal synthesis of IgG antibodies to MOG-Ig in multiple sclerosis.

The diagnostic value of sural nerve T cells in chronic inflammatory demyelinating polyneuropathy

BACKGROUND

T-cell infiltrates in sural nerve biopsy specimens of patients with inflammatory neuropathies have been reported, suggesting a role for T cells in the pathogenesis, but the specificity of the presence and localization of sural nerve T cells in chronic inflammatory demyelinating polyneuropathy (CIDP) is unknown.

OBJECTIVE

To study the diagnostic value of the number and distribution of sural nerve T cells in CIDP.

METHODS

We performed a quantitative immunohistochemical examination of T cells in sural nerve biopsy specimens taken from 23 patients with a CIDP and compared them with sural nerves of 15 patients with a chronic idiopathic axonal polyneuropathy (CIAP), 5 patients with a vasculitic neuropathy, and 10 normal controls.

RESULTS

T cells were found in sural nerves of all CIDP patients as well as in all disease and normal controls. Only six CIDP patients had increased numbers and densities of T cells compared with CIAP patients and controls. Based on the distribution of endoneurial or epineurial T cells, it was not possible to differentiate CIDP patients from CIAP patients or normal controls. In patients and controls perivascular epineurial T cells predominated. Increased numbers and densities of sural nerve T cells in patients with CIDP were associated with female sex, a more severe disease course, worse outcome, highly elevated CSF protein level, and a larger sural nerve area, but not with loss of myelinated nerve fibers in the sural nerve biopsy sample or demyelinating features on electrophysiologic examination.

CONCLUSIONS

In the majority of CIDP patients, the number and distribution of T cells in sural nerve biopsy samples were similar to patients with noninflammatory neuropathies and normal controls. Only large numbers of sural nerve T cells are specific for inflammatory neuropathies and therefore of diagnostic value for CIDP.

Local effects of recombinant rat interleukin-6 on the peripheral nervous system

Interleukin-6 (IL-6) is a multifunctional cytokine with a broad range of activities and can affect a variety of target cells or systems in multiple ways. However, there is currently no consensus on how IL-6 directly affects the peripheral nervous tissue. We performed histopathological and immunohistochemical analyses to investigate the direct effects of recombinant rat IL-6 (rrIL-6) following its intraneural injection into the sciatic nerve of adult Lewis rats. One day after injection, a large number of macrophages, major histocompatibility complex (MHC) class II positive cells, and CD4+ and CD8+ T cells appeared within the perineurium and endoneurium. From day 4 to day 7 after injection, we observed a gradual increase of inflammation and demyelination. On day 7, demyelination affected more than 80% of nerve fibres. In contrast, in the sterile phosphate-buffered saline (PBS)-injected control group, lower inflammation and fewer demyelinating nerve fibres were observed on days 4 and 7. Thus, intraneural injection of rrIL-6 into the sciatic nerve induces high inflammation and severe demyelination. This study improves our understanding of the effector mechanisms underlying inflammation and demyelination and identifies IL-6 as an essential mediator of inflammation and demyelination in the peripheral nervous system after local administration.

Encephalitogenic and neuritogenic T cell responses to the myelin-associated glycoprotein (MAG) in the Lewis rat

Autoimmune responses to the myelin-associated glycoprotein (MAG) are implicated in the immunopathogenesis of both multiple sclerosis (MS) and certain peripheral neuropathies. In this study we demonstrate that T cell responses to defined epitopes of MAG mediate a pathological inflammatory response in the nervous system of the Lewis rat. Peptide-specific T cells were generated against four different MAG epitopes, three of which are common to both L- and S-isoforms of MAG (amino acid (a.a.) sequence: 20-34, 124-137, 354-377) whilst the fourth epitope (a.a. sequence: 570-582) is located in the C-terminal sequence of S-MAG. The adoptive transfer of T cells specific for these epitopes initiated a mild but dose-dependent inflammatory response in the central nervous system (CNS) of naive recipients. Clinical disease was only observed in those animals injected with T cells specific for the a.a. sequence 20-34 (MP1.1), which also initiated an inflammatory response in the peripheral nervous system (PNS). Co-transfer of MP1.1 (a.a. sequence 20-34)-specific T cells with the myelin oligodendrocyte glycoprotein (MOG)-specific monoclonal antibody 8-18C5 enhanced disease severity and induced widespread demyelination in the CNS. In contrast, co-transfer of T cells with the MAG-specific mAb 513 failed to induce demyelination, but had a moderate effect on the local inflammatory response. The ability of MAG to initiate an autoaggressive T cell response in the Lewis rat supports the concept that MAG-specific autoimmune responses may play a role in the pathogenesis of immune mediated diseases of the nervous system in man.

MBP, anti-MBP and anti-PLP antibodies, and intrathecal complement activation in multiple sclerosis

Intrathecal immunoglobulin synthesis and activation of the complement cascade occurs in patients with multiple sclerosis (MS). The present study aimed at further studying the relation between intrathecal immunoglobulin synthesis and complement activation. We compared total intrathecal synthesis of IgA, IgG, and IgM, the number of cells secreting anti-myelin basic protein (MBP) and anti-proteolipid protein (PLP) antibodies of the IgG isotype and intrathecal activation of the complement cascade in patients with possible onset symptoms of MS (n = 18) or clinically definite MS (n = 30). Early activation of the complement cascade correlated with intrathecal synthesis of IgM. Intrathecal IgG, IgA and IgM synthesis also correlated weakly with the presence of cells secreting anti-MBP or anti-PLP autoantibodies. Full activation of the complement cascade did not correlate with any measures of intrathecal antibody synthesis. These findings suggest a complex relation between different immunoglobulin isotypes and complement activation which may have similarly complex roles in the pathogenesis of MS.

T cell antigenic and neuritogenic activity of recombinant human peripheral myelin P2 protein

The major neuritogenic protein of peripheral nerve myelin is the P2 protein. Human P2 is a candidate autoantigen in inflammatory demyelinating diseases of the peripheral nervous system. Since human P2 is not readily available, we produced full-length recombinant human P2 protein (rhP2) in Escherichia coli. RhP2 was recognized by neuritogenic rat T cell lines and induced experimental autoimmune neuritis in Lewis rats. Production of rhP2 allowed the generation of human T cell lines reactive to the autologous protein. Studies of human T cell autoreactivity as well as efforts to use hP2 as a tolerogen will be facilitated by the large-scale expression of rhP2.

Critical influences of the cytokine orchestration on the outcome of myelin antigen-specific T-cell autoimmunity in experimental autoimmune encephalomyelitis and multiple sclerosis

In EAE/MS, effector molecules are produced as a result of the interaction between T lymphocytes and antigen-presenting cells and the spectrum of cytokines produced is likely to decisively influence the disease outcome. These events may be more important, or at least more easily accessible to therapeutic intervention, than particular autoantigen specificities. Data from EAE suggest that cytokines connected to the Th1 phenotype of lymphocytes, especially IFN-gamma but also TNF-beta, TNF-alpha and IL-12, may promote inflammation while cytokines connected to the Th2 subset, IL-4, IL-10 and TGF-beta, may potentially have a role in disease limitation. It will be important to accurately study cytokines during immunotherapeutic interventions and in relation to immunogenetic variables in order to aim at immunotherapeutically intervening in the Th1, Th2 balance as well as counteracting disease-promoting cytokines such as IFN-gamma and TNF-alpha or promoting the action of downregulatory cytokines such as IL-10 and TGF-beta.

Multiple sclerosis:cerebrospinal fluid

Examination of cerebrospinal fluid (CSF) in the context of multiple sclerosis (MS), is valuable for several reasons. First, routine diagnostic evaluation of CSF cell counts and various forms of immunoglobulin determination are important to differentiate MS from other diseases. Second, because MS most probably is an organ-specific inflammatory disease and CSF is often the closest one can get to the target organ, examination of this fluid may allow basic studies on the immunopathogenesis of the disease, and indications of different aspects of inflammation should be considered when evaluating treatments aimed at reducing central nervous system inflammation. This article describes measurements taken at the cellular level in blood and CSF, of myelin-antigen autoreactive B- and T-cell responses, as well as cytokine production. Patients with MS display greatly increased numbers of cells in the CSF that produce antibodies against a variety of myelin antigens, such as myelin basic protein, proteolipid protein, and myelin-oligodendrocyte glycoprotein. Such antibodies may promote demyelination, and autoreactive B cells may enhance antigen presentation to T cells. There is also an increased number of T cells in MS, which in response to a broad range of myelin antigens and peptides, produce cytokines. The production of interferon-gamma, belonging to the T helper-1 type of cells, may have a disease up-regulatory role, while production of other cytokines, such as transforming growth factor beta, may counteract disease. Accurate measurements of cellular production of cytokines will be important in the design and monitoring of immunotherapy.