Multiple specificities of antibrain antibodies in multiple sclerosis and chronic myelopathy

Concurrent acute sensorimotor axonal neuropathy and disseminated encephalitis associated with Chlamydia pneumoniae in an adult patient with anti-MOG and anti-sulfatide antibodies: a case report

Acute disseminated encephalomyelitis and Guillain-Barré syndrome refer to post-infectious or post-vaccination inflammatory demyelinating disorders of central and peripheral nervous system, respectively. We report the case of a 60-year-old male patient presenting with irritability, gait difficulty, asymmetric quadriparesis (mostly in his left extremities), distal sensory loss for pain and temperature in left limbs, and reduced tendon reflexes in his upper limbs and absent in his lower limbs, following an upper respiratory tract infection, 3 weeks earlier. Brain magnetic resonance imaging revealed abnormal T2 signal and peripherally enhancing lesions in hemispheres, brainstem, and cerebellum. Nerve conduction studies were compatible with acute motor and sensory axonal neuropathy. Serology revealed positive IgM and IgG antibodies for Chlamydia pneumoniae, and he also tested positive for myelin oligodendrocyte glycoprotein (MOG) and sulfatide antibodies. Treatment with intravenous immunoglobulin and methylprednisolone led to clinical and radiological recovery within weeks. Even though several cases of combined central and peripheral demyelination have been reported before, it is the first case report with seropositive anti-sulfatide and anti-MOG acute sensorimotor axonal neuropathy and disseminated encephalitis associated with C. pneumoniae.

Myelin Basic Protein Attenuates Furin-Mediated Bri2 Cleavage and Postpones Its Membrane Trafficking

Myelin basic protein (MBP) is the second most abundant protein in the central nervous system and is responsible for structural maintenance of the myelin sheath covering axons. Previously, we showed that MBP has a more proactive role in the oligodendrocyte homeostasis, interacting with membrane-associated proteins, including integral membrane protein 2B (ITM2B or Bri2) that is associated with familial dementias. Here, we report that the molecular dynamics of the in silico-generated MBP-Bri2 complex revealed that MBP covers a significant portion of the Bri2 ectodomain, assumingly trapping the furin cleavage site, while the surface of the BRICHOS domain, which is responsible for the multimerization and activation of the Bri2 high-molecular-weight oligomer chaperone function, remains unmasked. These observations were supported by the co-expression of MBP with Bri2, its mature form, and disease-associated mutants, which showed that in mammalian cells, MBP indeed modulates the post-translational processing of Bri2 by restriction of the furin-catalyzed release of its C-terminal peptide. Moreover, we showed that the co-expression of MBP and Bri2 also leads to an altered cellular localization of Bri2, restricting its membrane trafficking independently of the MBP-mediated suppression of the Bri2 C-terminal peptide release. Further investigations should elucidate if these observations have physiological meaning in terms of Bri2 as a MBP chaperone activated by the MBP-dependent postponement of Bri2 membrane trafficking.

Sphingolipid Players in Multiple Sclerosis: Their Influence on the Initiation and Course of the Disease

Sphingolipids (SLs) play a significant role in the nervous system, as major components of the myelin sheath, contributors to lipid raft formation that organize intracellular processes, as well as active mediators of transport, signaling and the survival of neurons and glial cells. Alterations in SL metabolism and content are observed in the course of central nervous system diseases, including multiple sclerosis (MS). In this review, we summarize the current evidence from studies on SLs (particularly gangliosides), which may shed new light upon processes underlying the MS background. The relevant aspects of these studies include alterations of the SL profile in MS, the role of antibodies against SLs and complexes of SL-ligand-invariant NKT cells in the autoimmune response as the core pathomechanism in MS. The contribution of lipid-raft-associated SLs and SL-laden extracellular vesicles to the disease etiology is also discussed. These findings may have diagnostic implications, with SLs and anti-SL antibodies as potential markers of MS activity and progression. Intriguing prospects of novel therapeutic options in MS are associated with SL potential for myelin repair and neuroprotective effects, which have not been yet addressed by the available treatment strategies. Overall, all these concepts are promising and encourage the further development of SL-based studies in the field of MS.

New Insights into Multiple Sclerosis Mechanisms: Lipids on the Track to Control Inflammation and Neurodegeneration

Multiple sclerosis (MS) is a central nervous system disease with complex pathogenesis, including two main processes: immune-mediated inflammatory demyelination and progressive degeneration with axonal loss. Despite recent progress in our understanding and management of MS, availability of sensitive and specific biomarkers for these both processes, as well as neuroprotective therapeutic options targeted at progressive phase of disease, are still being sought. Given their abundance in the myelin sheath, lipids are believed to play a central role in underlying immunopathogenesis in MS and seem to be a promising subject of investigation in this field. On the basis of our previous research and a review of the literature, we discuss the current understanding of lipid-related mechanisms involved in active relapse, remission, and progression of MS. These insights highlight potential usefulness of lipid markers in prediction or monitoring the course of MS, particularly in its progressive stage, still insufficiently addressed. Furthermore, they raise hope for new, effective, and stage-specific treatment options, involving lipids as targets or carriers of therapeutic agents.

Multiple sclerosis: Serum anti-CNS autoantibodies

BACKGROUND

It is uncertain whether there are autoantibodies detectable by indirect immunofluorescence in the serum of patients with multiple sclerosis (MS).

OBJECTIVE

To determine whether there are anti-central nervous system (CNS) autoantibodies detectable by indirect immunofluorescence in the serum of MS patients.

METHODS

Sera and in some cases cerebrospinal fluid from 106 patients with multiple sclerosis, 156 patients with other neurological diseases, and 70 healthy control subjects were examined by indirect immunofluorescence using cryostat sections of rat cerebrum fixed by perfusion with paraformaldehyde.

RESULTS

Autoantibodies were detected that recognized more than 30 neuronal, glial, and mesodermal structures in 28 of 106 MS cases. Most were also detected in patients with other related and unrelated neurological diseases and several were also found in healthy controls. Novel anti-CNS autoantibodies recognizing particular sets of interneurons were detected in both normal controls and in subjects with CNS diseases.

INTERPRETATION

Serum anti-CNS autoantibodies of diverse specificities are common in MS patients. The same anti-CNS autoantibodies are not uncommon in patients with other neurological diseases. The findings provide no support for the proposition that myelin breakdown in MS is caused by exposure of intact myelin sheaths or oligodendrocytes to a pathogenic serum anti-myelin or anti-oligodendrocyte autoantibody.

Neuropilin-1 modulates interferon-γ-stimulated signaling in brain microvascular endothelial cells

Inflammatory response of blood-brain barrier (BBB) endothelial cells plays an important role in pathogenesis of many central nervous system inflammatory diseases, including multiple sclerosis; however, the molecular mechanism mediating BBB endothelial cell inflammatory response remains unclear. In this study, we first observed that knockdown of neuropilin-1 (NRP1), a co-receptor of several structurally diverse ligands, suppressed interferon-γ (IFNγ)-induced C-X-C motif chemokine 10 expression and activation of STAT1 in brain microvascular endothelial cells in a Rac1-dependent manner. Moreover, endothelial-specific NRP1-knockout mice, VECadherin-Cre-ERT2/NRP1^flox/flox mice, showed attenuated disease progression during experimental autoimmune encephalomyelitis, a mouse neuroinflammatory disease model. Detailed analysis utilizing histological staining, quantitative PCR, flow cytometry and magnetic resonance imaging demonstrated that deletion of endothelial NRP1 suppressed neuron demyelination, altered lymphocyte infiltration, preserved BBB function and decreased activation of the STAT1-CXCL10 pathway. Furthermore, increased expression of NRP1 was observed in endothelial cells of acute multiple sclerosis lesions. Our data identify a new molecular mechanism of brain microvascular endothelial inflammatory response through NRP1-IFNγ crosstalk that could be a potential target for intervention of endothelial cell dysfunction in neuroinflammatory diseases.

Implications of Lymphocyte Anergy to Glycolipids in Multiple Sclerosis (MS): iNKT Cells May Mediate the MS Infectious Trigger

Immunogenic lipids may play key roles in host defenses against infection and in generating autoimmune inflammation and organ-specific damage. In multiple sclerosis (MS) there are unequivocal autoimmune features and vulnerability to aggravation or induction by microbial or viral infection. We have found glycolipid-driven anergy of circulating lymphocytes in MS indicating that this immune response is affected in MS and the robust effects of iNKT activation with potent cellular and cytokine activities emphasizes its potential importance. Diverse glycolipids including the endogenous myelin acetylated-galactosylceramides (AcGalCer) can drive activation that could be critical to the inflammatory demyelination in the central nervous system and clinical consequences. The iNKT cells and their invariant or iTCR (Vα24Jα18Vβ11) receptor an innate defense–a discrete immune arm that is separate from peptide-driven acquired immune responses. This offers new possibilities for insight including a likelihood that the pattern recognition of exogenous microbial and myelin immunogens can overlap and cross-react especially in an inflammatory milieu.

Myelin glycosphingolipid immunoreactivity and CSF levels in multiple sclerosis

OBJECTIVES

Patients with multiple sclerosis were reported to harbour antibodies not only against proteins and glycoproteins but also against glycolipids, including sulfatide and galactosylceramide (GalCer), the two major glycosphingolipids of myelin. However, previous results were inconsistent concerning glycosphingolipid levels, antibody type, dominance of serum or Cerebrospinal fluid compartments and relationship to the multiple sclerosis (MS) course.

RESULTS

We hereby report that the cerebrospinal fluid levels of sulfatide were increased in patients with MS (n = 46) compared with controls (n = 50, P < 0.001). In addition, patients had higher serum IgM anti-glycosphingolipid titres than controls (P = 0.03 for sulfatide, <0.001 for GalCer), while the anti-glycosphingolipid IgM antibodies in the cerebrospinal fluid were essentially normal. However, in seven of 46 patients cerebrospinal fluid IgG antibodies against GalCer (P = 0.004) could be detected, which was not found in any of the control individuals, and this finding might mirror the occurrence of more specific B-cell clones behind the blood-brain barrier.

CONCLUSIONS

The IgM immunoreactivity in serum did not show any relationship to the type of course or severity of MS, arguing against a phenomenon secondary to myelin damage. Thus, the IgM antibody findings are compatible with an early antigen challenge or autoimmunity associated with natural antibodies.

The structural and functional role of myelin fast-migrating cerebrosides: pathological importance in multiple sclerosis

A family of neutral glycosphingolipids containing a 3-O-acetyl-sphingosine galactosylceramide (3-SAG) has been characterized. Seven new derivatives of galactosylceramide (GalCer), designated as fast-migrating cerebrosides (FMCs) by TLC retention factor, have been identified. The simplest compounds - FMC-1 and FMC-2 - of this series have been characterized as the 3-SAG containing nonhydroxy and hydroxy fatty acyl, respectively. The next two - FMC-3 and FMC-4 - add 6-O-acetyl-galactose and the most complex glycosphingolipids, FMC-5, -6 and -7, are 2,3,4,6-tetra-O-acetyl-3-SAG. These hydrophobic myelin lipid biomarkers coappear with GalCer during myelinogenesis and disappear along with GalCer in de- or dys-myelinating disorders. Myelin lipid antigens, including FMCs, are keys to myelin biology, opening the possibility of new and novel immune modulatory tools for treatment of autoimmune diseases including multiple sclerosis.

Molecular and immunogenic features of myelin lipids: incitants or modulators of multiple sclerosis?

Myelin lipids have long been thought to play intriguing roles in the pathogenesis of multiple sclerosis (MS). This review summarizes current understanding of the molecular basis of MS with emphasis on the: (i.) physico-chemical properties, organization and accessibility of the lipids and their distribution within the myelin multilayer; (ii.) characterization of myelin lipid structures, and structure-function relationships relevant to MS mechanisms, and; (iii.) immunogenic and other features of lipids in MS including molecular mimicry, lipid enzyme genetic knockouts, glycolipid-reactive NKT cells, and monoclonal antibody-induced remyelination. New findings associate anti-lipid antibodies with pathophysiological biomarkers and suggest clinical utility. The structure of CD1d-lipid complexed with the lipophilic invariant T cell receptor (iTCR) may be crucial to understanding MS pathogenesis, and design of lipid antigen-specific therapeutics. Novel immuno-modulatory tools for treatment of autoimmune diseases including MS in which there is both constraint of inflammation and stimulation of remyelination are now emerging.

Paraproteinemic neuropathy

Paraproteinemia frequently is associated with peripheral neuropathy. The clinical manifestations can be protean owing to the potential for multiple organ involvement. A methodical diagnostic approach to patients who have a plasma cell dyscrasia and neuropathy is necessary to ensure the appropriate detection of more widespread systemic involvement.

Developments in the prediction of type 1 diabetes mellitus, with special reference to insulin autoantibodies

The prodromal phase of type 1 diabetes is characterised by the appearance of multiple islet-cell related autoantibodies (Aab). The major target antigens are islet-cell antigen, glutamic acid decarboxylase (GAD), protein-tyrosine phosphatase-2 (IA-2) and insulin. Insulin autoantibodies (IAA), in contrast to the other autoimmune markers, are the only beta-cell specific antibodies. There is general consensus that the presence of multiple Aab (> or = 3) is associated with a high risk of developing diabetes, where the presence of a single islet-cell-related Aab has usually a low predictive value. The most commonly used assay format for the detection of Aab to GAD, IA-2 and insulin is the fluid-phase radiobinding assay. The RBA does not identify or measure Aab, but merely detects its presence. However, on the basis of molecular studies, disease-specific constructs of GAD and IA-2 have been employed leading to somewhat improved sensitivity and specificity of the RBA. Serological studies have shown epitope restriction of IAA that can differentiate diabetes-related from unrelated IAA, but current assays do not distinguish between disease-predictive and non-predictive IAA or between IAA and insulin antibodies (IA). More recently, phage display technology has been successful in identifying disease-specific anti-idiotopes of insulin. In addition, phage display has facilitated the in vitro production of antibodies with high affinity. Identification of disease-specific anti-idiotopes of insulin should enable the production of a high affinity reagent against the same anti-idiotope. Such a development would form the basis of a disease-specific radioimmunoassay able to identify and measure particular idiotypes, rather than merely detect and titrate IAA.

Anti-sulfatide IgM antibodies in peripheral neuropathy

Anti-sulfatide IgM antibodies have been recently associated with neuropathy but the clinical and electrophysiological correlations of this reactivity remains unclear. We reviewed the clinical and electrophysiological features of patients with high anti-sulfatide titers detected in our laboratory from 1991 to 1998. Of the 564 patients with different neurological diagnosis tested by enzyme-linked immunosorbent assay (ELISA), 11 had high anti-sulfatide IgM titers (>1/8000), 26 had titers of 1/8000 while 78 had titers of 1/4000. All patients with high anti-sulfatide IgM titers had a chronic, dysimmune, mostly sensorimotor neuropathy that in seven was associated with IgM monoclonal gammopathy. In most of these patients electrophysiological and morphological studies were consistent with a predominantly demyelinating neuropathy frequently associated with prominent axonal loss. Antibody titers of 1/8000, though always associated with neuropathy, did not correlate with a particular form or cause of neuropathy, while lower titers were equally distributed in patients with different neurological disorders. Our study indicate that high anti-sulfatide IgM titers (>1/8000) are highly predictive for a chronic, dysimmune, mostly demyelinating neuropathy often associated with IgM monoclonal gammopathy, and may therefore have potential diagnostic relevance.

Multiple sclerosis is associated with enhanced B cell responses to the ganglioside GD1a

The occurrence and role of autoantibodies to gangliosides and other lipid-containing components of the central nervous system in Multiple Sclerosis (MS) are unsettled. Using sensitive ELISAs, we measured IgG and IgM antibody titers and absorbances to the three major gangliosides GD1a, GD1b and GM1, and to sulfatides, cardiolipin and myelin proteins in paired serum and cerebrospinal fluid (CSF) from patients with untreated MS, optic neuritis (ON), acute aseptic meningo-encephalitis (AM) and other neurological diseases (OND). Twenty-three per cent of 30 MS (P<0.04) and 18% of 32 ON patients (P<0.05) presented elevated IgG antibody titers to GD1a in serum compared to 9% of patients with OND. Six (40%) of the patients with malignant MS had elevated serum IgG antibody titers to GD1a compared to one (6%) of the patients with benign MS (P<0.04). In CSF, elevated IgG antibody titers to GD1a were measured in 13% of MS and 20% of ON patients compared to 4% of patients with OND (P<0. 03 and P<0.02, respectively). The augmented IgG response to GD1a in serum also separated MS from Guillain-Barré syndrome. Compared to OND increased IgM absorbances to sulfatides and cardiolipin were observed in CSF of patients with MS, but also in AM. Elevated IgG antibody titers to myelin proteins were found more often in MS patients' serum and MS, ON and AM patients' CSF compared to OND. The data implicate that among the multitude of enhanced B-cell responses occurring in MS and ON, that directed to GD1a is common and more discriminative, and should be evaluated in future MS treatment studies.

High levels in serum, but no signs of intrathecal synthesis of anti-sulfatide antibodies in HIV-1 infected individuals with or without central nervous system complications

Myelin degeneration is commonly found in the central nervous system (CNS) of individuals infected with human immunodeficiency virus type 1 (HIV-1), especially in patients with HIV-1-associated dementia. We analysed cerebrospinal fluid (CSF) and serum samples from 25 HIV-1 infected individuals for the presence of antibodies directed against sulfatide, the major acidic glycosphingolipid in myelin. Nine of the patients had CNS complications, including 3 with HIV-1-associated dementia, and 16 had no neurological symptoms. Elevated titres of anti-sulfatide antibodies were found in serum from 24/25 HIV-1-infected individuals but in none of them in the CSF. Although the vast majority of HIV-1-infected individuals harbour autoantibodies directed against sulfatide in serum, the lack of detectable intrathecal production indicates that anti-sulfatide antibodies are not a major component in the pathogenesis of CNS myelin damage in HIV-1 infection.

Intrathecal synthesis of anti-sulfatide IgG is associated with peripheral nerve disease in acquired immunodeficiency syndrome

Peripheral nervous system involvement in the acquired immunodeficiency syndrome (AIDS) can take the form of an acute or chronic inflammatory demyelinating polyneuropathy, polyradiculopathy, mononeuropathy multiplex, or autonomic neuropathy. There is no widely held consensus on the etiology of PNS or other neurological complications associated with HIV infection. We report here that PNS disease in HIV-infected individuals is associated with intrathecal synthesis of an antibody directed against sulfatide, a major component of myelin. The anti-sulfatide antibody is also present nonspecifically in serum. The antibody requires the presence of the 3-O-sulfogalactosyl residue for binding and recognizes preferentially the hydroxy fatty acid-containing form of sulfatide. Anti-sulfatide antibodies are therefore one of the humoral factors responsible for demyelinating diseases in AIDS patients.

Anti-sulphatide antibodies in peripheral neuropathy

A study was carried out on 135 patients with chronic idiopathic neuropathy (63), neuropathy associated with monoclonal gammopathy (51, including eight with anti-MAG antibody activity) and the Guillain-Barré syndrome (GBS) (21). Serum IgM, IgG and IgA anti-sulphatide antibody titres were compared with titres in 304 patients with other neurological or immunological diseases and in 50 normal subjects. Titres were presented a) as the highest serum dilution at which reactivity could be detected, and b) in the linear region of the optical density curve. A substantial number of patients with neurological or immunological diseases had higher titres than normal subjects. Compared with normal and disease controls, five patients with neuropathy associated with IgMk monoclonal gammopathy had raised titres of IgM anti-sulphatide antibodies and one patient with GBS had raised IgM, IgG and IgA anti-sulphatide antibodies in the acute phase of the disease. Two patients had a predominantly axonal sensory neuropathy with presenting symptoms of painful paresthesiae and minimal neurological deficit. Three patients had a predominantly demyelinating sensorimotor neuropathy associated with anti-MAG antibody activity. The patient with GBS had extensive sensory loss and antibody titres returned to normal within three weeks. Raised titres of anti-sulphatide antibodies occurred in several types of neuropathy, but all had some degree of sensory impairment and associated immunological abnormality.

Antibodies to brain integral membrane proteins in systemic lupus erythematosus

Wheat germ lectin affinity chromatography and temperature-induced phase separation with Triton X-114 were evaluated for the isolation of surface neuronal antigens from rat and human brain and from human neuroblastoma cell lines IMR-6 and SK-N-SH. Both techniques yielded surface proteins which were free of contamination by intracellular proteins but temperature-induced phase separation was technically less demanding and less expensive, required a shorter assay time and resulted in a superior quantity and quality of isolated proteins. Rat brain surface proteins were used for characterization of antineuronal antibody reactivity in sera from patients with systemic lupus erythematosus (SLE). Western blotting identified reactivity in 15 of 75 (20%) SLE sera compared to five of 95 (5%) normal controls (P 0.006). In rat brain the molecular weight of the individual proteins identified ranged from 59 kDa to 22 kDa. Six of these were also present in human brain and two were present in neuroblastoma cell lines. Absorption studies indicated that some of the antigenic proteins were either restricted to brain tissue or shared with other non-neuronal tissues. These techniques should facilitate the characterization of antineuronal antibody reactivities and lead to a clearer understanding of their role in the pathogenesis of autoimmune neurologic disease.

Anti-sulfatide antibodies in neurological disease: binding to rat dorsal root ganglia neurons

Increased titers of anti-sulfatide antibodies were detected by ELISA in 5 of 200 patients and control subjects. All 5 patients had sensory impairment; 4 had neuropathy, and one had multiple sclerosis. Of the patients with neuropathy, 2 had a clinical syndrome of small fiber sensory neuropathy with normal electrophysiological or nerve biopsy studies, 1 had a sensorimotor axonal neuropathy associated with IgM monoclonal gammopathy, and 1 had sensorimotor neuropathy with multifocal motor conduction block and anti-GM1 antibodies. The anti-sulfatide antibodies bound to the surface of unfixed rat dorsal root ganglia neurons and human neuroblastoma cells, and to fixed sections of central and peripheral myelin. No binding was detected following intraneural injection into rat sciatic nerves. Pre-absorption with sulfatide but not with galactocerebroside eliminated the tissue binding activity. These findings indicate that increased titers of anti-sulfatide antibodies are found in patients with sensory impairment but are not restricted to a particular neurological syndrome or type of neuropathy. The significance of anti-sulfatide antibodies is uncertain although sulfatide on dorsal root ganglia neurons may be a target antigen.

Non-specific binding of normal human IgG, including F(ab')2 and Fc fragments, to embryonic rat brain neurons and human cortex synaptosomes

Binding of normal human IgG to embryonic rat brain neurons was quantitated by flow cytometry. IgG binding was linear between 0.05 and 1.5 mg/ml; slight binding was detectable even at normal cerebrospinal fluid concentrations. Similar binding curves were obtained for purified Fc and F(ab')2 fragments from normal human IgG. Normal human IgG also bound to synaptosomes (resealed nerve terminals) from human cerebral cortex. However, competition assays utilizing 125I-IgG showed no evidence for specific binding. This study indicates that the specificity of putative anti-neuronal antibodies should be confirmed by competition assays as for other receptor-ligand binding.

Cerebrospinal fluid and serum antiphospholipid antibodies in multiple sclerosis, Guillain-Barré syndrome and systemic lupus erythematosus

Immunoglobulins isotypes (IgG and IgM) for myelin basic protein (MBP), cerebrosides (CER), gangliosides (GANG) and cardiolipin (CARD) were detected in the cerebrospinal fluid (CSF) from 33 patients with multiple sclerosis (MS), 18 with Guillain-Barré syndrome (GBS) and 30 with systemic lupus erythematosus (SLE). In MS patients occurred positive and significant levels of IgG-MBP in 51.5% (p less than 0.05) and IgM-MBP in only 18.2%, IgG-CARD in 46.2%, as long as CER and GANG were detected in almost 20%. From serum samples of MS patients 20.6% presented IgG-MBP, while 53% showed positive levels for IgM-MBP. The CSF analysis of patients with GBS showed that 56.3% revealed IgG-MBP (p less than 0.05), 53% for IgM-MBP, 38.5% for IgG-CER and 23% for IgM-CER, while 50% of patients had IgG-CARD, as long as 31% also had IgG-GANG. The serum evaluation from 14 patients showed that 18.8% had positive concentrations of IgG-MBP and 56.3% presented IgM-MBP (p less than 0.05). Except for 50% of patients with SLE who presented positive CSF levels of IgG-CARD, only 24.1% had positive levels of IgG-MBP. We believe that the presence of antiphospholipid antibodies in CSF of the above mentioned diseases occurred as immune epiphenomena, but their appearance would permit the maintenance of and perpetuate the immune event.

Monoclonal autoantibodies derived from multiple sclerosis patients and control persons and their reactivities with antigens of the central nervous system

Peripheral blood B lymphocytes of multiple sclerosis (MS) patients and control persons were transformed with Epstein-Barr virus. Antibody production of transformed cells against isolated human myelin was investigated by enzyme-linked immunosorbent assay (ELISA). Cells producing reactive antibodies were cloned and propagated to produce monoclonal antibodies (mAbs). These mAbs did also react with acetone fixed frozen sections of normal human white matter, as determined by indirect immunofluorescence staining. Some of the mAbs derived from MS patients and a control person with a central nervous system cyst agglutinated liposomes made from lipids of a chloroform/methanol extract of human myelin, whereas mAbs derived from four glioma patients were negative in these tests. The reactive antibodies were investigated further using agglutination tests with liposomes made from pure auxiliary lipids (cholesterol and lecithin) or containing in addition either galactocerebroside, sulfatide or a mixture of bovine brain gangliosides. The great majority of myelin liposome agglutinating antibodies reacted with all types of liposomes, including those made from pure auxiliary lipids. Investigations by ELISA suggest that phospholipids are the reactive components, at least for some of these mAbs. Some antibodies reacted with liposomes containing galactocerebroside or sulfatide, others only with sulfatide containing liposomes. Antibodies showing these specificities were only obtained from MS patients.

Screening of multiple sclerosis cerebrospinal fluid for autoantibodies

An enzyme-linked immunoadsorbent assay, using nitrocellulose discs as solid phase and small sample volumes (50 microliter), was developed for the measurement of antibodies. This was used to screen CSF samples for autoantibodies against tissue components. Extracts from a selection of tissues from both "normal" and MS patients and from 3 glial cell lines were made in phosphate-buffered saline; in the case of neural and lymphoid samples the remaining particulate materials were subsequently solubilised with octylglucoside. The saline-soluble components were screened against CSF samples from MS patients (18), patients with other neurological disorders (10), and matched orthopaedic patients but no differences were found among the 3 groups. However, when the detergent-soluble components were screened a significant (at the P less than or equal to 0.01 level) elevation of reactivity towards brain was found in 6/16 MS patients and 2/12 patients with other neurological diseases when compared to their controls.

The detection of brain antigens within the circulating immune complexes of patients with multiple sclerosis

Immune complexes isolated from sera of patients with multiple sclerosis (MS) were analyzed for their antigenic content. Immune complexes precipitated with polyethylene glycol were inoculated into rabbits. The antisera raised were shown to react to MS and normal brain antigens by crossed immunoelectrophoresis, ELISA and nitrocellulose transfer. Additionally, these antisera reacted by co-precipitation with the measles nucleocapsid antigen. As persistent viral infection has not been shown to occur in MS, these studies support the possibility that brain antigens within the immune complex share antigenic determinants with a specific viral antigen seen earlier in life by the host.

Are anti-brain antibodies in multiple sclerosis directed to myelin basic protein? Studies employing the Shiverer mouse mutant

The dysmyelinating mouse mutant Shiverer has a severe and relatively selective deficiency of myelin basic protein (MBP) in the central and peripheral nervous system. Nevertheless, Shiverer brain and control-mouse brain showed similar antigenic titers when tested by a complement fixation assay against a panel of 14 multiple sclerosis (MS) sera and 6 MS CSF samples known to represent several specificities of antibrain antibodies. By analogy with experimental allergic encephalomyelitis, a sensitization to MBP has been proposed in MS. Our results, however, show that antibodies to other CNS antigens are quantitatively more important in this disease.

Antiglycolipid antibodies in normal and pathologic human sera and synovial fluids

Antiglycolipid antibodies were measured in normal and pathologic sera and synovial fluids by means of a modified microplate method of complement-mediated immune lysis of fluorescent dye-trapped liposomes. All sera of normal subjects had antibodies against globopentaosylceramide (IV3 GalNAcGbOse4Cer), ganglioside GM1, gangliotriaosylceramide, gangliotetraosylceramide, and galactosylneolactotetraosylceramide antigens. Most sera of normal subjects had antibodies against lactotriaosylceramide, N-glycolylneuraminosyl-neolactotetraosylceramide (NeuGcnLcOse4Cer), GM3 ganglioside with N-glycolylneuraminic acid (NeuGcGM3) and GD1a antigens. Differences of titers against IV3GalNAcGbOse4Cer, neolactotetraosylceramide, NeuGcGM3 and NeuGcnLcOse4Cer antigens were observed between sera of normal subjects and pathologic sera from cases of leukemias, lymphomas, several autoimmune diseases and liver diseases.

Antisera to different glycolipids induce myelin alterations in mouse spinal cord tissue cultures

To study the demyelinative effects of antibodies to glycolipids, well-myelinated cultures of mouse spinal cord tissue were exposed to antisera against galactocerebroside and two gangliosides (GM1 and GM4), as well as to anti-white matter antiserum. The demyelinative process was evaluated by morphologic and biochemical techniques. Cultures exposed to anti-white matter and anti-galactocerebroside antisera showed the most marked changes. These consisted of a decrease in the number of oligodendroglial cells and dissolution and phagocytosis of myelin. Concomitantly, the activity of 2',3'-cyclic nucleotide-3'-phosphohydrolase (CNPase) was decreased by 60-70%. This occurred within 24 h of exposure to a relatively low concentration of serum (10%). Cultures exposed to anti-GM1 and anti-GM4 antisera showed similar changes but to a lesser degree. The CNPase activity was decreased about 30% within 48 h of exposure to a 25% concentration of these antisera. This diminution represents about a 20% loss of myelin, an observation corroborated by electron microscopy where myelin but not oligodendroglial cell loss was observed. Therefore, in addition to anti-galactocerebroside activity, which was previously found to be the major antibody responsible for the demyelinating activity induced by anti-whole CNS tissue antiserum, these data suggest that antibodies to gangliosides like GM1 and GM4 might also play a role in immune-mediated demyelination, including perhaps, the human demyelinating diseases.

Immune responses to myelin antigens in multiple sclerosis

Multiple sclerosis is considered to be a putative immunopathologic disease and there has been considerable effort over the years to prove an autoimmune etiology for it. To date, the evidence is all indirect and there is no proof of either antibody and/or cell-mediated hypersensitivity to any single identifiable CNS constituent whether a constituent of normal CNS or specific to the CNS of MS patients.

Antibodies to glycosphingolipids in patients with multiple sclerosis

Antibodies to one or more glycosphingolipids were detected by means of a liposome lysis assay in the sera of 60/81 patients with multiple sclerosis, 24/42 patients with systemic lupus erythematosus and in the majority of patients with cranial trauma or cerebrovascular accidents. Antibodies against ganglioside GM1 and asialo GM1 were found most commonly and they were frequently present in the same sera. Among patients whose sera contained antibodies to glycolipids, anti-GM1 alone occurred more frequently in patients with multiple sclerosis (14/59) than in systemic lupus erythematosus (1/22; p = 0.045) and antiasialo GM1 alone was more common in patients with lupus (9/22) than in patients with multiple sclerosis (8/59, p = 0.007). In 10 sera analyzed, all of the antibodies against these two glycolipids were of the IgM class, and some fluctuation in antibody titers was noted over a three-month period. The role of these antibodies in the initiation or perpetuation of inflammatory diseases of the central nervous system remains to be determined.

A review of the immunogenic and immuno-modulatory properties of glycosphingolipids

This review summarizes recent data concerning the immunogenicity and immunomodulatory properties of glycosphingolipids. Many murine monoclonal antibodies that react with glycosphingolipids have been described recently. Most of these antibodies have been elicited by immunization with tumor cells and they may also bind to glycoproteins that contain similar carbohydrate sequences. Immunization with a variety of tissues, murine teratocarcinomas, myeloid leukemia, and carcinomas of the human lung, colon and stomach, has elicited antibodies that react with the sugar sequence Gal beta 1-4[Fuc alpha 1-3]GlcNAc beta 1-3Gal----. The suppression of lymphocyte responses to mitogens and antigens by gangliosides in vitro has led to suggestions that these glycolipids possess immunodulatory properties in vivo. The in vitro studies were performed by incubating mononuclear cells with either dispersions of pure gangliosides or ganglioside-containing liposomes. In vivo gangliosides are found only in cell membranes or in lipoproteins, where they represent a small mole percent of total lipids, and there is little information about the transfer of gangliosides from lipoproteins to cells in vivo. A role for gangliosides as modulators of the immune response is an interesting possibility that is not supported by physiologically relevant data at present.

Rat CNS cell culture. Enhancement of neuronal survival and delay of glial proliferation by serum from patients with multiple sclerosis. A morphological study

The addition of serum from multiple sclerosis (MS) patients to the culture medium of dissociated cells from cerebral hemispheres of rat embryos caused a delay in glial proliferation and an enhancement of neuronal survival. Sera from normal individuals and patients with other neurological diseases failed to show this effect. These morphological observations are interpreted as the outcome of inhibition of in vitro gliogenesis.

New approach to study of in vitro toxicity of multiple sclerosis and other sera

The in vitro effects of MS and control sera were quantified by the measurement of radiolabel released from myelinated cultures of rat cerebellum and compared with a visual assessment of myelin damage. Radiolabel release gave a sensitive index of serum effects in vitro which was free of the score assignment decisions that are associated with the visual assessment of myelin damage. Examination of the patterns of radiolabel release elicited by MS and control sera on cultures labelled with either L-[5-3H]tryptophan or galacto-D-[6-3H]cerebroside indicates that MS serum effects are not simply a stronger expression of the weak control serum effects.

CSF antibodies to myelin basic protein and to myelin-associated glycoprotein in multiple sclerosis. Evidence of the intrathecal production of antibodies

Cerebrospinal fluid (CSF) from 40 multiple sclerosis (MS) patients was tested by solid-phase radioimmunoassay (RIA) for ability to bind 2 common structural components of myelin and oligodendroglia, i.e., to bind myelin basic protein (MBP) and myelin-associated glycoprotein (MAG). To prevent the effect of differences in CSF IgG concentration on binding activity, the CSF samples were tested at equal IgG concentration 1 mg/ml. The mean binding activity to MBP and MAG was significantly higher than in control neurotics, respectively P less than or equal to 0.05 and P less than or equal to 0.001. In 33% of MS cases, CSF antibody against both antigens was found. Indirect data were obtained that autoantibodies whose antigens are associated with myelin-oligodendrocyte unit are produced locally within the central nervous system (CNS). Anti-MAG and anti-MBP CSF antibody activity was significantly higher, P less than or equal to 0.01 for both antibody specificity, in MS cases characterized by high IgG Index, greater than or equal to 0.70 = means + SD in the neurotic group, versus MS cases characterized by normal IgG Index (less than or equal to 0.70). Correlation coefficient between antibody activity and IgG Index values was 0.785 for anti-MBP antibody, and 0.400 for anti-MAG antibody. The importance of intrathecally produced antibody to MBP and MAG lies in the fact that it indicates an active humoral autoimmune process against a myelin-oligodendrocyte unit in which more than one autoantigen is involved.

Estimation of levels of IgG to multiple sclerosis specific brain antigens in the cerebrospinal fluid of MS patients

The binding of partially purified multiple sclerosis (MS) specific brain antigens (MSG2) and of the corresponding antigens of non-MS brains (KG2) to cerebrospinal fluid IgG of patients with MS and other neurological diseases was assayed employing sandwich enzyme linked immunosorbent assay (ELISA). Assay of the antigen-antibody binding revealed that the concentration of MSG2 required for the optimum binding to IgG in the undiluted MS CSFs was lower than that of KG2 in all cases. The index for IgG binding capacity of an antigen (IgBC) was expressed as a ratio of the optical density of the enzymic products in ELISA at the optimal antigen-antibody binding to the lowest concentration of the antigen required for the optimal binding. The IgBC of MSG2 was found to be linearly correlated with the IgG concentration in the CSF of MS patients. These results indicate that IgG with specificity to MSG2 may be present in the CSF of MS patients.

CSF antibodies to myelin basic protein and oligodendrocytes in multiple sclerosis and other neurological diseases

Cerebrospinal fluid (CSF) from 18 multiple sclerosis (MS) patients, 13 subacute sclerosing panencephalitis (SSPE) patients, 22 other neurological disease (OND) patients, and 7 neurotic patients as controls were tested in an 125I-labeled anti-human F(ab')2 binding assay for the presence of antibodies to normal human brain cells from tissue culture, human fibroblasts, plasma membranes of MS and normal human brain, myelin basic protein (MBP) and bovine oligodendrocytes. Antibodies to MBP and to oligodendrocytes were found in the CSF of MS, SSPE and OND patients. Absorption of CSF with bovine CNS myelin significantly diminished binding activity to oligodendrocytes. Antibodies in the CSF against MBP and oligodendrocytes, on which some myelin determinants are expressed, seem to be a common feature of diseases in which demyelination is a component.

Chronic relapsing experimental allergic encephalomyelitis: its value as an experimental model for multiple sclerosis

Comparison of the pathohistology of chronic relapsing experimental allergic encephalomyelitis (CR-EAE) and multiple sclerosis (MS) reveals a close similarity. Thus, CR-EAE appears to be a valuable model for the study of pathogenetic factors leading to the formation of MS lesions, although the induction of the disease may be different (active sensitization with CNS antigens and adjuvant in CR-EAE versus unknown etiology in MS). CR-EAE furthermore mimicks the pathohistological patterns of other related human inflammatory demyelinating diseases (i.e., acute perivenous leukoencephalomyelitis and acute hemorrhagic leukoencephalomyelitis). The expression of an acute, predominantly inflammatory versus chronic inflammatory demyelinating disease in this model depends upon the time interval between sensitization and sampling of the animals. Recent evidence is discussed that a cooperation between cellular and humoral immune mechanisms, directed against multiple CNS antigens, is responsible for the formation of large demyelinated plaques in EAE and MS.

Anticomplementary activity in multiple sclerosis

Anticomplementary activity (ACA) is a common problem in serological work. Often it is regarded as an indicator of circulating immune complexes and has been clinically used as such. In a longitudinal study (Ryberg 1982b) ACA was determined in heated (56 degrees C for 30 min) sera from 35 MS patients followed for up to 5 years; in 18 of them ACA in heated CSF was also assayed. Persistent or transitory ACA of low titre was found in some sequences, usually without evident correlation with clinical events. Marked ACA in unheated sera was found more often in MS patients than in controls and showed dramatic changes in most of 15 sequences studied for this property, sometimes in a way suggesting a correlation with clinical exacerbations. This activity was heat labile and was not bound by an immunosorbent with affinity to human IgG and, therefore, is not likely to represent IgG containing aggregates or immune complexes.

Immunological reactions against Mycoplasma pneumoniae in multiple sclerosis: preliminary findings

Humoral and cellular immune reactions against Mycoplasma pneumoniae (MPn) were investigated in 18 multiple sclerosis (MS) patients. All patients were in the remission stage. Complement-fixing antibodies against MPn were present in serum and cerebrospinal fluid, concentrated to contain the same protein levels. The CSF titres after concentration were as high as or higher than the corresponding serum titres, thus indicating intrathecal antibody production. Sensitization to MPn was demonstrable in all 18 MS patients by the antigen-reactive active E-rosette assay and antibody-dependent cellular cytotoxicity assay, in 17 of the 18 patients by the lymphocyte transformation test and in 8 patients by the cell-mediated cytotoxicity assay. The possibility of a pathogenetic role of MPn for MS is discussed.

Antibodies in cerebrospinal fluid to white matter glycoproteins in multiple sclerosis patients

Cerebrospinal fluid (CSF) specimens from 45 patients with multiple sclerosis (MS) and 45 age- and sex-matched controls with other neurological diseases (OND) were tested for antibodies to white matter (WM) membrane glycoprotein (GP) fractions prepared from MS and control WM membranes by lentil lectin chromatography. The binding of the CSF IgG to the 125I-labeled GP fractions was determined by immunoprecipitation using Protein A-Sepharose. CSF from patients with MS bound highly significantly more strongly to the GP fraction prepared from MS WM than did the OND CSF specimens (P less than 0.001). There was no such difference when control GP fraction was used as an antigen. No highly significant differences were observed when 20 paired serum specimens were tested. Electrophoresis of the immunoprecipitates showed that components with molecular weights (MWs) of 157,300, 135,600, 111,100, 93,000, 75,700, 63,300, 50,100, 24,300, 20,300 and 17,000 daltons were precipitated from the MS GP fraction by CSF specimens of both MS and OND groups, whereas components with MWs of 50,100, 24,300, 20,300 and 17,000 daltons were precipitated from the control GP fraction.

The ontogenetic mouse brain model employed in the characterization of antibrain antibodies in multiple sclerosis

The complement-fixing antibrain antibodies which may be found in patients with multiple sclerosis (MS) belong to several specificities, of which only two are as yet identified. In order to study three of the incompletely characterized specificities, the ontogenetic evolution of the corresponding antigens in mouse brain was followed. MS serum containing antibodies to sulfatide, a relatively myelin-specific glycolipid, served as a control. The studied antigens were virtually absent at birth and accumulated at different rates during the postnatal period. The results give valuable clues for the further study of the antibrain antibodies in MS.

A longitudinal study of antibrain antibodies in multiple sclerosis

The presence of complement-fixing antibrain antibodies is a distinctive feature of multiple sclerosis (MS). In a longitudinal study of 35 MS patients antibrain antibody titres in serum were followed for up to 5 years; in 18 of them also CSF titres were determined. No consistent correlations between antibrain antibody titres and clinical events were found. Thus, MS relapses are not caused by a general increase in antibrain antibody titres, and conversely the relapses did not cause a boosting of antibrain antibodies. Significant variations in the local plaque environment are, however, not ruled out by the present results.

Antibrain antibodies in multiple sclerosis. Relation to clinical variables

IgG antibrain antibodies (ABA) of several specificities can be demonstrated in multiple sclerosis (MS) with the complement fixation technique. This technique seems to discriminate between IgG specifically and non-specifically bound to CNS preparations. Complement-fixing ABA were titrated in paired serum and CSF samples from 87 patients with clinically definite MS, 15 patients with probable MS, 29 patients with other neurological diseases, and 13 "healthy" controls. In addition, sera from 55 non-MS patients were tested. In 40% of the sera and 88% of the CSF samples from patients with clinically definite MS, ABA reacting with human brain homogenate were demonstrated. The corresponding figures for probable MS were 21% and 73%, and for the controls 11% and 6%. Two of 9 sera from patients with the Guillain-Barré syndrome were strongly positive. There was a tendency for higher CSF ABA titres in younger MS patients and in those with an earlier onset of disease. ABA titres in serum and CSF were both correlated with a more malignant course. Irrespective of the mechanism of induction of ABA in MS--an excessive immunogenic stimulation and/or a defective immunoregulation--they are potentially pathogenic in several ways, e.g. (1) by direct antibody action. (2) by interaction with complement, (3) by antibody-dependent K-cell-mediated cytotoxicity, and (4) by interaction with phagocytic cells. Of several correlations among the routine CSF variables in MS, the finding of more pronounced abnormalities in male patients was notable.