Monoclonal IgM in a patient with paraproteinemic polyneuropathy binds to gangliosides containing disialosyl groups

Waldenström Macroglobulinemia - A State-of-the-Art Review: Part 1: Epidemiology, Pathogenesis, Clinicopathologic Characteristics, Differential Diagnosis, Risk Stratification, and Clinical Problems

Waldenström macroglobulinemia (WM) is an infrequent variant of lymphoma, classified as a B-cell malignancy identified by the presence of IgM paraprotein, infiltration of clonal, small lymphoplasmacytic B cells in the bone marrow, and the MYD88 L265P mutation, which is observed in over 90% of cases. The direct invasion of the malignant cells into tissues like lymph nodes and spleen, along with the immune response related to IgM, can also lead to various health complications, such as cytopenias, hyperviscosity, peripheral neuropathy, amyloidosis, and Bing-Neel syndrome. Chemoimmunotherapy has historically been considered the preferred treatment for WM, wherein the combination of rituximab and nucleoside analogs, alkylating drugs, or proteasome inhibitors has exhibited notable efficacy in inhibiting tumor growth. Recent studies have provided evidence that Bruton Tyrosine Kinase inhibitors (BTKI), either used independently or in conjunction with other drugs, have been shown to be effective and safe in the treatment of WM. The disease is considered to be non-curable, with a median life expectancy of 10 to 12 years.

Campylobacter jejuni Infection, Anti-Ganglioside Antibodies, and Neuropathy

Preceding infection with Campylobacter jejuni (Cj) occurs in approximately 30% of patients with Guillain–Barre syndrome (GBS), and the risk of GBS following Cj infection is increased by 77 to 100-fold. GBS is most often of the axonal subtype and is thought to be mediated by IgG antibodies to peripheral nerve gangliosides that are cross reactive with oligosaccharides in the Cj lipopolysaccharides (LPS). The antibodies are thought to be induced by molecular mimicry, where immune reactivity to a cross reactive epitope in the infectious organism and normal tissue can cause autoimmune disease. Clonally restricted IgM antibodies that react with the same oligosaccharides in gangliosides and Cj-LPS are associated with chronic neuropathies of otherwise similar phenotypes. The anti-ganglioside antibodies in GBS are of the IgG1 and IgG3 subclasses, indicating T-cell reactivity to the same antigens that could help disrupt the blood–nerve barrier. Cj infection can activate multiple innate and adoptive pro-inflammatory pathways that can overcome immune tolerance and induce autoimmunity. Elucidation of the specific immune mechanisms involved in the development of the autoantibodies and neuropathy would help our understanding of the relation between infection and autoimmunity and aid in the development of more effective preventive interventions and therapies.

Polyneuropathy Associated with IgM Monoclonal Gammopathy; Advances in Genetics and Treatment, Focusing on Anti-MAG Antibodies

With increasing age, the chances of developing either MGUS or polyneuropathy increase as well. In some cases, there is a causative relationship between the IgM M-protein and polyneuropathy. In approximately half of these cases, IgM targets the myelin-associated glycoprotein (MAG). This results in chronic polyneuropathy with slowly progressive, predominantly sensory neurological deficits and distally demyelinating features in nerve conduction studies. Despite the disease being chronic and developing slowly, it can cause considerable impairment. We reviewed English medical publications between 1980 and May 2022 on IgM gammopathy-associated polyneuropathy, with special attention to studies addressing the pathophysiology or treatment of anti-MAG polyneuropathy. Treatment options have been limited to a temporizing effect of intravenous immunoglobulins in some patients and a more sustained effect of rituximab but in only 30 to 55 percent of patients. An increase in our knowledge concerning genetic mutations, particularly the MYD88L265P mutation, led to the development of novel targeted treatment options such as BTK inhibitors. Similarly, due to the increasing knowledge of the pathophysiology of anti-MAG polyneuropathy, new treatment options are emerging. Since anti-MAG polyneuropathy is a rare disease with diverse symptomatology, large trials with good outcome measures are a challenge.

Anti-disialosyl-IgM chronic autoimmune neuropathies: a nationwide multicenter retrospective study

BACKGROUND & PURPOSE

In this retrospective study involving 14 University Hospitals from France and Switzerland, we aimed at defining the clinicopathologic features of chronic neuropathies with anti-disialosyl ganglioside IgM antibodies (CNDA).

RESULTS

Fifty-five patients with a polyneuropathy evolving for more than 2 months and with at least one anti-disialosyl ganglioside IgM antibody, i.e., anti-GD1b, -GT1b, -GQ1b, -GT1a, -GD2 and -GD3 were identified. Seventy-eight percent of patients were male, mean age at disease onset was 55 years (30-76), and disease onset was progressive (82%) or acute (18%). Patients presented with limb sensory symptoms (94% of cases), sensory ataxia (85%), oculomotor weakness (36%), limb motor symptoms (31%), and bulbar muscles weakness (18%). Sixty-five percent of patients had a demyelinating polyradiculoneuropathy electrodiagnostic profile, and 24% a sensory neuronopathy profile. Anti-GD1b antibodies were found in 78% of cases, while other anti-disialosyl antibodies were each observed in less than 51% of patients. Other features included nerve biopsy demyelination (100% of cases), increased cerebrospinal fluid protein content (75%), IgM paraprotein (50%), and malignant hemopathy (8%). Eighty six percent of CNDA patients were intravenous immunoglobulins (IVIg)-responsive, and rituximab was successfully used as second-line treatment in 50% of cases. Fifteen percent of patients had mild symptoms and were not treated. CNDA course was progressive (55%) or relapsing (45%), and 93% of patients still walked after a mean disease duration of 11 years.

CONCLUSION

CNDA have a recognizable phenotype, are mostly IgIV-responsive, and present with a good outcome in a majority of cases.

CANOMAD: a neurological monoclonal gammopathy of clinical significance that benefits from B-cell-targeted therapies

CANOMAD (chronic ataxic neuropathy, ophthalmoplegia, immunoglobulin M [IgM] paraprotein, cold agglutinins, and disialosyl antibodies) is a rare syndrome characterized by chronic neuropathy with sensory ataxia, ocular, and/or bulbar motor weakness in the presence of a monoclonal IgM reacting against gangliosides containing disialosyl epitopes. Data regarding associated hematologic malignancies and effective therapies in CANOMAD are scarce. We conducted a French multicenter retrospective study that included 45 patients with serum IgM antibodies reacting against disialosyl epitopes in the context of evocating neurologic symptoms. The main clinical features were sensitive symptoms (ataxia, paresthesia, hypoesthesia; n = 45, 100%), motor weakness (n = 18, 40%), ophthalmoplegia (n = 20, 45%), and bulbar symptoms (n = 6, 13%). Forty-five percent of the cohort had moderate to severe disability (modified Rankin score, 3-5). Cold agglutinins were identified in 15 (34%) patients. Electrophysiologic studies showed a demyelinating or axonal pattern in, respectively, 60% and 27% of cases. All patients had serum monoclonal IgM gammopathy (median, 2.6 g/L; range, 0.1-40 g/L). Overt hematologic malignancies were diagnosed in 16 patients (36%), with the most frequent being Waldenström macroglobulinemia (n = 9, 20%). Forty-one patients (91%) required treatment of CANOMAD. Intravenous immunoglobulins (IVIg) and rituximab-based regimens were the most effective therapies with, respectively, 53% and 52% of partial or better clinical responses. Corticosteroids and immunosuppressive drugs were largely ineffective. Although more studies are warranted to better define the optimal therapeutic sequence, IVIg should be proposed as the standard of care for first-line treatment and rituximab-based regimens for second-line treatment. These compiled data argue for CANOMAD to be included in neurologic monoclonal gammopathy of clinical significance.

Autoimmune Peripheral Neuropathies and Contribution of Antiganglioside/Sulphatide Autoantibody Testing

Peripheral immune-mediated polyneuropathies (IMPN) are a diverse group of rare neurological illnesses characterized by nerve damage. Leading morphological features are mostly nerve fibre demyelination or combination of axonal damage and demyelination. There has been remarkable progress in the clinical and electrophysiological categorization of acute (fulminant, life-threatening) and chronic (progressive/remitting-relapsing) immune-mediated neuropathies recently. Besides electrophysiological and morphological makers, autoantibodies against glycolipids or paranodal/nodal molecules have been recommended as candidate markers for IMPN. The progress in testing for autoantibodies (autoAbs) to glycolipids such as gangliosides and sulfatide may have significant implications on the stratification of patients and their treatment response. Thus, this topic was reviewed in a presentation held during the 1st Panhellenic Congress of Autoimmune Diseases, Rheumatology and Clinical Immunology in Portaria, Pelion, Greece. For acute IMPN, often referred to as Guillain-Barré syndrome and its variants, several serological markers including autoAbs to gangliosides and sulphatide have been employed successfully in clinical routine. However, the evolution of serological diagnosis of chronic variants, such as chronic inflammatory demyelinating polyneuropathy or multifocal motor neuropathy, is less satisfactory. Serological diagnostic markers could, therefore, help in the differential diagnosis due to their assumed pathogenic role. Additionally, stratification of patients to improve their response to treatment may be possible. In general, a majority of patients respond well to causal therapy that includes intravenous immunoglobulins and plasmapheresis. As second line therapy options, biologicals (e.g., rituximab) and immunosuppressant or immunomodulatory drugs may be considered when patients do not respond adequately.

Diffuse large B-cell lymphoma involving peripheral nervous system with IgM antibodies against GM1 and GD1b: A case report

RATIONALE

The occurrence of peripheral neuropathy associated with non-Hodgkin's lymphoma (NHL) is uncommon. And autoimmunity may play an important role. We report a case of the patient with NHL, has sensorimotor demyelinating polyneuropathy.

PATIENT CONCERNS

The patient presented with a 1-month history of progressive numbness at the distal extremities and motor weakness of the lower limbs. Meanwhile, patient also endorsed a painful lump on her right cheek. And then the enlarged cervical and supra clavicular lymph nodes were observed on admission. Biopsy of the lymph nodes showed NHL. Serum IgM antibodies against GM1 and GD1b were also positive.

DIAGNOSIS

Biopsy of the lymph nodes showed NHL. Serum IgM antibodies against GM1 and GD1b were also positive. Thus, the patience was diagnosed with lymphoma and sensorimotor polyneuropathy.

INTERVENTIONS

Patient refused the further treatment.

OUTCOMES

After 11-month follow-up, the weakness of bilateral lower limbs worsens.

LESSONS

We have presented a case of NHL involving peripheral polyneuropathy with IgM antibodies against GM1 and GD1b. Patients may initially present with peripheral nerve complications or develop them during the course of lymphoma, even when in remission. This could complicate the diagnosis of peripheral polyneuropathy secondary to NHL.

Nodes, paranodes and neuropathies

This review summarises recent evidence supporting the involvement of the specialised nodal and perinodal domains (the paranode and juxtaparanode) of myelinated axons in the pathology of acquired, inflammatory, peripheral neuropathies.The identification of new target antigens in the inflammatory neuropathies heralds a revolution in diagnosis, and has already begun to inform increasingly targeted and individualised therapies. Rapid progress in our basic understanding of the highly specialised nodal regions of peripheral nerves serves to strengthen the links between their unique microstructural identities, functions and pathologies. In this context, the detection of autoantibodies directed against nodal and perinodal targets is likely to be of increasing clinical importance. Antiganglioside antibodies have long been used in clinical practice as diagnostic serum biomarkers, and associate with specific clinical variants but not to the common forms of either acute or chronic demyelinating autoimmune neuropathy. It is now apparent that antibodies directed against several region-specific cell adhesion molecules, including neurofascin, contactin and contactin-associated protein, can be linked to phenotypically distinct peripheral neuropathies. Importantly, the immunological characteristics of these antibodies facilitate the prediction of treatment responsiveness.

The Spectrum and Pathogenesis of Antibody-mediated Neuropathies

Antibodies reacting with carbohydrate epitopes on neural glycoconjugates are present in several forms of neuropathy. These include monoclonal antibodies to the myelin-associated glycoprotein (MAG) and to gan gliosides in patients with neuropathy in association with IgM gammopathy, as well as polyclonal antibodies to gangliosides in inflammatory polyneuropathies, such as Guillain-Barré syndrome and multifocal motor neuropathy. There are several correlations between antibody specificity and clinical symptoms, including anti-MAG antibodies with demyelinating sensory or sensorimotor neuropathy, anti-GM1 ganglioside anti bodies with motor nerve disorders, anti-GQ1b ganglioside antibodies with Miller-Fisher syndrome, and antibodies to gangliosides containing disialosyl moieties with sensory ataxic neuropathy. This review will emphasize recent developments concerning the origins of the anti-glycoconjugate antibodies in patients, pathogenic mechanisms by which the antibodies may cause the neuropathies, and the implications of these findings for therapy. NEUROSCIENTIST 3:195-204, 1997

Immune-mediated Neuropathy with Anti-disialosyl IgM Antibodies in Diffuse Large B-cell Lymphoma: A Case Report and Literature Review

A 36-year-old man with diffuse large B-cell lymphoma presented with polyneuropathy, and the diagnostic work-up revealed the presence of IgM antibodies against gangliosides with disialosyl residues (GD1b, GD3). He was treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone and received high-dose intravenous immunoglobulin for the treatment of neuropathy. After initiating the treatments, the patient's neurological impairment improved dramatically. He currently remains in complete remission without a flare-up of the polyneuropathy. Based upon our experience and other case reports of lymphoma with immune-mediated neuropathy caused by anti-disialosyl ganglioside IgM antibodies, we conclude that determining the anti-ganglioside antibody profile and beginning early treatment should be considered promptly for patients with malignant lymphoma who develop polyneuropathy.

CANOMAD responding to weekly treatment with intravenous immunoglobulin (IVIg)

A 48-year-old man presented with numbness in fingers and diplopia 1 week after a flu-like illness. He made a full recovery but 8 years later developed progressive and disabling sensory ataxia. He had superimposed acute flare-ups with numbness, double vision and ptosis, all following infections. A blood test showed antidisialosyl antibodies including GD1b, GD3, GT1b and GQ1b in keeping with the diagnosis of chronic ataxic neuropathy, ophthalmoplegia, IgM paraprotein, cold agglutinins and antidisialosyl antibodies (CANOMAD). Initial treatment with monthly courses of intravenous immunoglobulin (IVIg) 0.4 g/kg/day for 5 days every 4 weeks helped temporarily but there were marked disabling fluctuations of symptoms. With IVIg 0.6 g/kg/day weekly his symptoms are stable. He remains mobile and has no eye symptoms without need for any other medication. This case demonstrates that weekly IVIg infusions instead of one 5-day course monthly may be able to avoid fluctuations of symptoms in CANOMAD.

Paraproteinemic neuropathies

The term paraproteinemic neuropathy refers to a heterogeneous group of neuropathies, which share the common feature of a homogeneous immunoglobulin in the serum. The presence of a monoclonal gammopathy indicates an underlying clonal B-cell expansion, which may appear in the context of a lymphoproliferative disorder. If a neoplastic origin of the gammopathy is identified, the treatment should be targeted to the neoplasm. In most patients, however, the monoclonal gammopathy is not associated with malignant haematological disorders, and is defined as monoclonal gammopathy of undetermined significance.

Antibody testing in peripheral nerve disorders

The identification of autoantibodies associated with dysimmune neuropathies was a major contribution to the characterization of peripheral nerve disorders, the understanding of their pathophysiology, and the clinical diagnosis of neuropathies. Antibodies directed to GM1, GQ1b, and disyalilated gangliosides, and anti-MAG antibodies are very useful in the diagnosis of acute or chronic motor or sensory-motor neuropathies with or without monoclonal IgM. Anti-onconeural anti-Hu and anti-CV2/CRMP antibodies allow when they are detected the diagnosis of paraneoplastic neuropathies. This chapter focuses on the description of these antibodies as diagnostic markers and on their immunopathogenesis. We give a background overview on the origin of these antibodies, their detection, and review those studies, which clearly show that these antibodies are capable of binding to the target tissues in peripheral nerve and thereby can exert a variety of pathophysiological effects. The corresponding electrophysiological and histological changes observed both in human and animal models are exemplified in order to get a better understanding of the immune mechanisms of these antibody-mediated neuropathies.

Neuropathy and monoclonal gammopathy

The association of neuropathy with monoclonal gammopathy has been known for several years, even if the clinical and pathogenetic relevance of this association is not completely defined. This is not a marginal problem since monoclonal gammopathy is present in 1-3% of the population above 50 years in whom it is often asymptomatic, and in at least 8% of patients is associated with a symptomatic neuropathy, representing one of the leading causes of neuropathy in aged people. Monoclonal gammopathy may result from malignant lymphoproliferative diseases including multiple myeloma or solitary plasmocytoma, Waldenström's macroglobulinemia (WM), other IgM-secreting lymphoma or chronic lymphocytic leukemia, and primary systemic amyloidosis (AL). In most instances it is not associated with any of these disorders and is defined monoclonal gammopathy of undetermined significance (MGUS) for its possible, though infrequent, evolution into malignant forms. Several data support the pathogenetic role of the monoclonal gammopathy in the neuropathy particularly when of IgM isotype where IgM reactivity to several neural antigens has been reported. Increased levels of VEGF have been implicated in POEMS syndrome. However, there are as yet no defined therapies for these neuropathies, as their efficacy has not been confirmed in randomized trials.

Canomad presenting without ophthalmoplegia and responding to intravenous immunoglobulin

The acronym CANOMAD encompasses chronic ataxic neuropathy combined with ophthalmoplegia, M protein, cold agglutinins, and anti-disialosyl antibodies.Herein we describe 2 patients presenting with progressive ataxic neuropathy who only developed ophthalmoplegia after a significant delay post-presentation, which in 1 case had features indicative of brainstem dysfunction. Both patients were found to have an IgM paraprotein and anti-disialosyl antibodies. They responded to treatment with intravenous immunoglobulin, thus illustrating the importance of diagnosing this condition.

Induction of experimental ataxic sensory neuronopathy in cats by immunization with purified SGPG

IgM paraproteins in about 50% of the patients with neuropathy associated with IgM gammopathy react with carbohydrate moieties in myelin-associated glycoprotein (MAG) and in sulfated glucuronic glycolipids (SGGLs) in human peripheral nerves. However, the role of anti-MAG/SGGL antibodies in the pathogenesis of neuropathy remains unclear. In order to induce an animal model of neuropathy associated with anti-MAG/SGGL antibodies, cats were immunized with sulfoglucuronyl paragloboside (SGPG). All four cats immunized with SGPG developed clinical signs of sensory neuronopathy within 11 months after initial immunization, characterized by unsteadiness, falling, hind limb weakness and ataxia. In two cats the ataxia and hind limb paralysis were so severe that the animals had to be euthanized. Pathological examination revealed sensory ganglionitis with inflammatory infiltrates in the dorsal root ganglia. No overt signs of pathology were noted in the examined roots or nerves. High titer anti-SGPG/MAG antibodies were detected in all 4 cats immunized with SGPG but not in 3 control cats. Our data demonstrate that immunization of cats with SGPG induced anti-SGPG antibodies and sensory neuronopathy clinically resembling the sensory ataxia of patients with monoclonal IgM anti-MAG/SGPG antibodies. This study suggests that these anti-MAG/SGPG antibodies play a role in the pathogenesis of this neuropathy.

Antibody testing in peripheral neuropathies

Many autoantibodies have been described in association with peripheral neuropathy, but the use of antibody testing in clinical practice remains a matter of some debate. Serum autoantibodies to gangliosides or glycoproteins are implicated in a variety of sensory and motor neuropathy syndromes. Paraneoplastic antibodies help identify patients who have a neuropathy related to an underlying malignancy. Detection of an autoantibody in the right clinical setting provides some evidence that the peripheral nerve disturbance is immune mediated and that immunomodulatory therapy may be of benefit.

Long-term evolution of anti-ganglioside antibody levels in patient with chronic dysimmune neuropathy under IVIg therapy

The authors retrospectively examined the anti-ganglioside antibody (AGA) IgM level changes from 14 patients with chronic dysimmune neuropathy (5 with multifocal motor neuropathy and 9 with chronic inflammatory demyelinating polyneuropathy) treated with maintenance doses of intravenous immunoglobulins (IVIg). The median follow-up was 5 years. At last follow-up, 93% of the patients had an increment of AGA levels, and five patients with initial AGA values within normal range became positive during follow-up. Overall, median AGA titers significantly increased from the first to the last samples, despite a substantial clinical stability after the initial improvement with IVIg. The AGA increment rate was inversely correlated with IVIg infusions interval necessary to maintain therapeutic efficacy. Thus, antibody testing in the follow-up of patients with dysimmune neuropathies may be helpful to predict the decline of IVIg efficacy and to identify those patients who eventually take advantage from an increase in infusion frequency.

Relapsing sensorimotor neuropathy with ophthalmoplegia, antidisialosyl antibodies, and extramembranous glomerulonephritis

A 72-year-old man presented with oculomotor dysfunction, subacute relapsing sensorimotor neuropathy, elevated erythrocyte sedimentation rate, IgM monoclonal paraprotein, cold agglutinins, and antidisialosyl IgM antibodies, features previously described by the acronym CANOMAD (chronic ataxic neuropathy with ophthalmoplegia, M protein, agglutination, and disialosyl antibodies). The patient also had extramembranous glomerulopathy associated with this syndrome. Treatment with corticosteroids improved both the neuropathy and glomerulopathy. This case suggests that the spectrum of neuropathy associated with monoclonal gammopathy may be broader than originally believed.

Paraproteinemic neuropathies

The occurrence of a peripheral neuropathy (PN) in association with a monoclonal gammopathy is quite common and suggests that monoclonal proteins may play a pathogenetic role in peripheral nervous system damage. In fact, paraproteinemic PN constitute an heterogeneous group of disorders related to various pathogenetic factors, and the histopathologic features in peripheral nerve biopsies differ from one condition to another. In several well defined disorders, the responsibility of the monoclonal component in the development of the PN has been evidenced. This is the case for most of the PN associated with an IgM monoclonal gammopathy, either a monoclonal gammopathy of undetermined significance (MGUS) or Waldenstrom's macroglobulinemia. The responsibility of the monoclonal protein in the occurrence of amyloid neuropathy related to multiple myeloma is also recognized. However, most IgG or IgA MGUS, as well as the monoclonal component in POEMS syndrome, have an uncertain causal relationship with the neuropathy. PN associated with monoclonal cryoglobulin (type 1) are occasional and differ from those associated with mixed cryoglobulins (types 2 or 3).

Paraproteinaemic neuropathies

In this article, we review the main clinical and pathological features of paraproteinaemic neuropathies and discuss recent experimental findings. Further knowledge of the disease process at the molecular level has allowed a better characterization of clinical syndromes and has given new insights into their pathogenesis. The most convincing evidence for a causal relationship can be drawn from IgM monoclonal gammopathies with specificities directed against carbohydrate determinants of the myelin associated glycoprotein (MAG). There remain however, many unresolved questions, such as how monoclonal anti-MAG IgM antibodies cross the blood-nerve barrier and trigger a chronic demyelinating polyneuropathy while the central nervous system is essentially spared. IgM paraproteins with specificity for other molecules, such as neurofilaments, sulphatide, gangliosides, chondroitin sulphate and tubulin, have also been identified, but their pathogenetic importance remains to be elucidated. Other paraproteinaemic neuropathies such as IgG and IgA neuropathies have to be considered separately. The paraneoplastic endocrine and cytokine manifestations of rare osteosclerotic myelomas provide valuable insights into the interaction between the immune and the nervous system. The antigen-specificity of IgG and IgA monoclonal antibodies are only poorly characterized but some have been found to be directed against endoneurial determinants and a few against axonal proteins such as neurofilaments.

Neuropathology of paraneoplastic neuropathy with anti-disialosyl antibody

We report a paraneoplastic neuropathy with severe motor involvement following sensory-ataxic disturbance. Anti-disialosyl immunoglobulin M (IgM) antibody was detected in the course of malignant lymphoma of diffuse large B-cell type, which usually spares the motor system. Onset was subacute, with relapsing and remitting sensory ataxia, muscle weakness, bulbar palsy, respiratory paralysis, and ophthalmoplegia; only neck rotation was retained in the terminal stage. Autopsy showed no lymphoma cells infiltrating the nervous system. Motor neurons survived in the spinal cord, but mean diameter of the ventral spinal nerve roots was reduced considerably. The gracile fasciculus and the sural nerve were more markedly degenerated than proximal portions. Morphometric study showed that most of the proximal motor and sensory axons did not extend distally. This autopsy report provides further definition of a neuropathy associated with malignant lymphoma and IgM antibodies against disialosyl residues.

Pathogenicity of anti-ganglioside antibodies in the Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is a postinfectious inflammatory polyradiculo-neuropathy characterized by flaccid paralysis. Antibodies directed against glycolipid structures (gangliosides), which are highly expressed in the peripheral nervous system, are frequently detected in sera from GBS patients. These antibodies interfere with nerve conduction and have been shown to activate phagocytes via IgG receptors (FcgammaR). These findings support an important role of glycolipid-specific antibodies in the pathogenesis of GBS.

Severe sensory ataxia and demyelinating polyneuropathy with IgM anti-GM2 and GalNAc-GD1A antibodies

Several polyneuropathy syndromes have been described with polyclonal serum immunoglobulin G (IgG) or immunoglobulin M (IgM) binding to gangliosides GM2 and GalNAc-GD1a that contain the terminal trisaccharide moiety GalNAc(beta1-4)Gal(alpha2-3)NeuAc. We describe the clinical and electrodiagnostic features in two patients with serum IgM monoclonal anti-GM2 and anti-GalNAc-GD1a antibodies. These patients had slowly progressive, panmodal sensory loss with severe sensory ataxia. Electrodiagnostic testing showed demyelinating features. Prominent improvement in gait ataxia occurred after treatment with human immune globulin but not after other immunomodulating therapies. Enzyme-linked immunoabsorbent assay and thin-layer chromatography demonstrate that the patient's serum monoclonal IgM bound to gangliosides GM2 and GalNac-GD1a but not to gangliosides without the GalNAc(beta1-4)Gal(alpha2-3)NeuAc moiety. This neuropathy differs from previously reported neuropathy syndromes associated with polyclonal GM2 and GalNAc-GD1a antibodies and from other chronic demyelinating polyneuropathies. We conclude that a distinct syndrome of chronic demyelinating neuropathy with sensory ataxia, unresponsive to corticosteroids, is associated with monoclonal IgM binding to gangliosides with a terminal GalNAc(beta1-4)Gal(alpha2-3)NeuAc trisaccharide moiety. Diagnosis of this syndrome is important to direct appropriate treatment.

Antiganglioside antibodies in acute self-limiting ataxic neuropathy: incidence and significance

Antidisialosyl antibodies have been previously associated to chronic and acute ataxic neuropathies. We studied the presence of these antibodies in nine patients with acute self-limiting ataxic neuropathy (ASLAN) using ELISA and TLC immunodetection. One patient showed serum IgG immunoreactivity against gangliosides GD3 and GQ1b. The patient's IgG was able to bind to the nodes of Ranvier on frozen human dorsal root. Our studies confirmed that antidisialosyl reactivity is associated to ataxic neuropathy and its specific binding to the dorsal root could explain the predominant sensory involvement. Nevertheless, the low incidence of this reactivity indicates that a different pathogenic mechanism should be involved in most ASLAN patients.

Sensorimotor demyelinating neuropathy with IgM antibody against gangliosides GD1a, GT1b and GM3

We report a patient with sensorimotor demyelinating neuropathy with high-titer IgM antibody against gangliosides GD1a, GT1b and GM3. The patient was a 65-year-old male who was hospitalized with chief complaints of muscular weakness of all limbs and numbness of the hands and feet. Nerve-conduction studies revealed reduced conduction velocities of the motor nerves with increased temporal dispersion and loss of sensory nerve action potentials. Treatment with steroids was ineffective. IgM antibody against GD1a, GT1b and GM3, which are known to be the ligands for myelin-associated glycoprotein (MAG), might have played a role in the demyelination in this patient by inhibiting adhesion between myelin and axonal membrane.

Features of sensory ataxic neuropathy associated with anti-GD1b IgM antibody

Some reports have called sensory ataxic neuropathy (SAN) associated with IgM antibody against b-series gangliosides a chronic form of Miller Fisher syndrome (MFS), but this has yet to be established. We examined five patients with SAN and eight patients with IgG anti-GQ1b-positive MFS. Only one patient with SAN complained of diplopia, whose ocular movement was not limited. The other four patients had neither diplopia nor limitation of ocular movement. All the SAN patients had severe deep sense impairment, whereas one patient with MFS showed only mild vibratory sense impairment. All sera from the SAN patients had remarkably high IgM antibody titers to the b-series gangliosides GD3, GD2, GD1b, GT1b, GQ1b, GQ1b alpha, fucosyl-GD1b, and alpha galactosyl [alpha fucosyl] GD1b. An absorption study confirmed that the anti-GQ1b antibodies cross-reacted with GD3, GD2, GD1b, and GT1b. In contrast, only two samples from the MFS patients had IgG antibody to GD3, and no sample reacted with GD2, GD1b, or GT1b. SAN has different clinical or serological features from MFS, and therefore is not a chronic form of it.

Ganglioside agglutination immunoassay for rapid detection of autoantibodies in immune-mediated neuropathy

Elevated levels of serum autoantibodies directed against gangliosides are closely associated with acute and chronic autoimmune neuropathies. An agglutination immunoassay using polystyrene microparticles coated with a total extract of brain gangliosides was used to test patient sera for the presence of anti-ganglioside antibodies. Results were compared with those obtained by ELISA for anti-GM1 and anti-GQ1b ganglioside antibodies. Eight of the twelve sera from patients with multifocal motor neuropathy and seven of the thirteen sera from patients with Guillain-Barré syndrome were positive for the presence of anti-ganglioside antibodies by the ganglioside agglutination immunoassay. The assay compared favorably with the ELISA system in sensitivity and specificity, while requiring a fraction of the time and cost to perform. The new assay can serve as a rapid and effective method for detecting or screening for anti-ganglioside antibodies in patients with acute or chronic immune-mediated neuropathies. It would be particularly useful for detecting antibodies that react with multiple gangliosides, or with minor or as yet uncharacterized gangliosides.

Detection of antibody to sialyl-i, a possible antigen in patients with Meniere's disease

An autoimmune hypothesis for the etiology of Meniere's disease has been proposed. In this study, we focused on gangliosides as potential antigens for autoantibodies in Meniere's disease patients. In an attempt to investigate ganglioside antigens which respond to the serum of patients with Meniere's disease, we analyzed gangliosides of human acoustic neurinomas, and used them as antigens to broadly explore gangliosides that react to serum. All the acoustic neurinoma samples used in the present study showed a similar ganglioside profile on TLC (thin-layer chromatography). For the microscale ganglioside analysis, a newly developed TLC blotting/secondary ion mass spectrometry (SIMS) system together with TLC immunostaining method was employed. Most of the ganglioside bands could be analyzed, and they were identified as GM3, GM2, SPG, GM1a, GD3, S-i (sialyl-i ganglioside) and GD1a. GD1a was the predominant ganglioside and many neolactoseries gangliosides were recognized by immunological analysis. Next, the immune reactivity of serum samples, from patients with Meniere's disease, with the acoustic neurinoma gangliosides was studied by TLC immunostaining. The result showed that five of 11 patients with Meniere's disease and one of eight normal subjects reacted with a specific band, which was identified as S-i by the TLC blotting/SIMS system. The findings of the present study indicate that S-i ganglioside is an autoantigen and possibly involved in the pathogenesis of Meniere's disease.

Ataxic form of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)

We reported a 64-year-old male with an eight-month history of gait disturbance and sensory impairment. The patient initially noticed unsteadiness of gait and numbness in his feet, and these symptoms progressed until he was unable to walk without assistance five months later. Vibratory sensation and position sense were markedly diminished, and deep tendon reflexes were absent in all extremities. Motor conduction velocities were slow with prolonged distal latencies, and sensory nerve action potentials (SNAP) were not elicited. Sural nerve biopsy revealed a mild loss of myelinated fibres and segmental demyelination. Cerebrospinal fluid showed normal cell count with protein 526 mg/dL. Anti-GM1, anti-GM2 and anti-GA1 antibodies in serum were positive. We diagnosed chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) presenting ataxia. Steroid therapy provided immediate improvement of symptoms and signs. This case suggests that CIDP should be considered as one of the potential causes of ataxic neuropathy.

Waldenström's macroglobulinemia: clinical features, complications, and management

PURPOSE

To review the clinical features, complications, and treatment of Waldenström's macroglobulinemia, a low-grade lymphoproliferative disorder that produces monoclonal immunoglobulin (Ig) M.

METHODS

A review of published reports was facilitated by the use of a MEDLINE computer search and by manual search of the Index Medicus.

RESULTS

The clinical manifestations associated with Waldenström's macroglobulinemia can be classified according to those related to direct tumor infiltration, to the amount and specific properties of circulating IgM, and to the deposition of IgM in various tissues. Asymptomatic patients should be followed without treatment. For symptomatic patients, standard treatment consists primarily of oral chlorambucil; nucleoside analogs, such as fludarabine and cladribine, are effective in one third of previously treated patients and in up to 80% of previously untreated patients. Preliminary evidence suggests that anti-CD20 monoclonal antibody may be active in about 30% of previously treated patients and that high-dose therapy with autologous stem-cell rescue is effective in most patients, including some with resistance to nucleoside analogs.

CONCLUSION

Waldenström's macroglobulinemia has a wide clinical spectrum that practicing physicians need to recognize early to reach the correct diagnosis. When therapy is indicated, oral chlorambucil is the standard primary treatment, but cladribine or fludarabine can be used when a rapid cytoreduction is desirable. Prospective randomized trials are required to elucidate the impact of nucleoside analogs on patients' survival. A nucleoside analog is the treatment of choice for patients who have been previously treated with an alkylating agent.

The immunopathogenesis of Miller Fisher syndrome

Over the past decade, remarkable progress has been made in our understanding of the pathogenesis of Miller Fisher syndrome (MFS), a clinical variant of Guillain Barré syndrome (GBS). MFS comprises the clinical triad of ataxia, areflexia and ophthalmoplegia. It is associated with acute-phase IgG antibodies to GQ1b and GT1a gangliosides in over 90% of cases which are highly disease specific. Like GBS, MFS is a post-infectious syndrome following diverse infections, but particular attention has been paid to its association with Campylobacter jejuni enteritis. Serostrains of C. jejuni isolated from infected patients bear ganglioside-like epitopes in their lipopolysaccharide core oligosaccharides, which elicit humoral immune responses exhibiting molecular mimicry with GQ1b/GT1a gangliosides. These antibodies are believed to be the principal cause of the syndrome and physiological studies aimed at proving this have focused on the motor-nerve terminal as a potential site of pathogenic action. This review describes these findings and formulates a pathogenesis model based on our current state of knowledge.