Antisera to the ganglioside GM1 do not have anti-myelin or anti-axon activities in vitro

Myelin Antigens and Antimyelin Antibodies

The purpose of this review is to provide an historical perspective on studies of serum derived antimyelin antibodies. Antimyelin antibodies can be defined by their action on myelinating organotypic nervous system tissue cultures and include demyelinating antibodies, which have destructive effects on myelin when applied to already myelinated cultures, and myelination inhibiting antibodies, which prevent myelin formation when applied to cultures prior to myelination. Myelin antigens were evaluated in animal studies for their ability to induce experimental allergic encephalomyelitis, an inflammatory demyelinating disease, and correlated with the induction of antimyelin antibodies. As tissue culture demyelinating activity was also found in sera from some patients with multiple sclerosis, a human inflammatory demyelinating disease, studies were undertaken to characterize the nature of the demyelinating factors.

Antiglycolipid antibodies in motor neuropathies

In peripheral neuropathies with monoclonal gammopathy, mainly IgM, it appears clear from clinical, electrophysiological, and experimental data, that the target glycolipid or glycolipid epitope for the IgM is related to the type of neuropathy--purely sensory, predominantly sensory, or uniquely motor. Investigations have focused on chronic peripheral neuropathies associated with polyclonal IgM reactivity to glycolipids. Although IgM anti-GM1 antibodies are present in normal controls, there is a subgroup of motor neuropathies with high titer anti-GM1 antibodies, mainly multifocal neuropathies with conduction blocks (MMNCB). Another subgroup of MMNCB may include IgM anti-SGPG antibodies that do not cross-react with MAG. The importance of the fine structure of the epitope has to be considered in view of the pathogenicity of the antibody. It may bear consequences on its binding properties on the neuronal surfaces and on its biological implications.

In vitro modulation of changes in ganglioside patterns of differentiating neurons in the presence of an anti-GM1 antibody

Retinal cells from 7-day-old chicken embryos were cultured in the presence of a polyclonal anti-GM1 antibody, at low and high density in a "sandwich cell culture". Cells that were about 80% neurofilament positive at all times, changed their morphology and emitted processes as controls. By examining immunocytochemical expression of gangliosides, cells cultured in the presence of the antibody maintained GD3 expression longer than controls, albeit the expression of the gangliotetraosylgangliosides (GTOG) was not considerably affected. This leads to an extension of the transient period in which differentiating cells coexpressed both types of gangliosides (GD3 and GTOG). At 3-4 days in vitro the relative synthesis of GD3 was about 30% higher and that of GD1a about 40% lower than in controls, indicating a delay in the shift of the synthesis pattern. Nevertheless, the pattern of ganglioside composition resembled at 4 days in vitro. Results indicate that the anti-GM1 antibody may modulate the expression and synthesis of gangliosides without a detectable decrease in neuritogenesis. Considering that the emission of neurites occurs in coexpressing GD3 and GTOG neurons, it is suggested that neuritogenesis could be irrespective of losing the GD3 expression.

Inhibition of neurite outgrowth of neuroblastoma Neuro-2a cells by cholera toxin B-subunit and anti-GM1 antibody

The role of cell surface GM1 ganglioside in neurite outgrowth of Neuro-2a neuroblastoma cells was investigated by application of anti-GM1 antibody and the B subunit of cholera toxin (cholera B) to cultured cells stimulated to grow neurites in various ways. When the cells were simultaneously treated with stimulatory agent and cholera B, inhibition, as measured by percent of neurite-bearing cells, was observed with most stimuli: neuraminidase; GD1a ganglioside, retinoic acid, and low serum. However, with dibutyryl cyclic AMP the small reduction observed was not statistically significant. The inhibitory effect of cholera B on neurite outgrowth induced by low serum was dose-dependent, reaching a maximum at 200 ng/mL; 48 h after washout of cholera B the cells were released from inhibition and regrew neurites at nearly the previous rate in the presence of low serum. When the cells were exposed to stimulus for 6 h or more the inhibitory effect of subsequent addition of cholera B was reduced or eliminated; inhibition thus occurs during an early stage of neurite initiation. Anti-GM1 antibody at dilutions of 1:100-1:400 had the same inhibitory effect as cholera B with cells stimulated by GD1a or retinoic acid, whereas anti-GM2 antibody had no effect at 1:200 or 1:400; inhibition by the latter antibody at 1:100 dilution was similar to that attained with control ascites fluid. These results point to a pivotal role for cell surface GM1 in Neuro-2a differentiation induced by many (but not all) neuritogenic agents.

CSF and serum ganglioside antibody patterns in MS

The authors determined CSF and serum IgG and IgM antibodies to seven gangliosides in 48 patients with multiple sclerosis. Differing ganglioside antibody patterns in CSF but not serum allowed to reclassify 93% of MS patients correctly when compared to patients with Guillain-Barré syndrome or neuroborreliosis. This suggest that the antibody patterns are neither random nor alike in inflammatory diseases of the nervous system. CSF ganglioside antibody titres were found to be different for patients with relapsing remitting (RRMS; n = 35) and chronic progressive (CPMS; n = 13) multiple sclerosis. Our study reveals characteristic ganglioside antibody patterns in MS and confirms previous evidence of disturbed immunoregulation in MS.

Effects of Guillain-Barré sera containing antibodies against glycolipids in cultures of rat Schwann cells and sensory neurons

Serum samples from 52 patients with the acute Guillain-Barré syndrome (GBS), 19 patients with other neurological disorders, and 18 healthy volunteers were tested for cytotoxicity in cultures of rat Schwann cells and dorsal root ganglion neurons. The samples were also examined by enzyme-linked immunosorbent assay for IgG and IgM antibodies against various acidic and neutral glycolipids. Samples from 16 of the 52 (31%) acute GBS patients and from 1 of the 6 patients with chronic inflammatory demyelinating polyneuropathy produced myelin breakdown in culture. Although 10 of the 16 cytotoxic acute GBS serum samples contained anti-glycolipid immunoglobulins, there was no correlation in individual samples between cytotoxic activity and the presence of antibodies against specific glycolipids. While our results do not exclude a role for anti-glycolipid antibodies in the pathogenesis of the acute GBS, the cytotoxic effects of acute GBS serum in cultures of Schwann cells and sensory neurons are probably not due to these antibodies alone.

Ganglioside antibodies: a lack of diagnostic specificity and clinical utility?

Serum IgG and IgM antibodies to gangliosides GM1, GM2, GM3, AGM1, GD1a, GD1b and GT1b were determined in 210 patients with different degenerative and inflammatory disorders including motor neuron diseases, peripheral radiculopathies and neuropathies, multiple sclerosis and neuroborreliosis. No single disorder was associated specifically with ganglioside antibodies. No characteristic patterns of ganglioside antibodies were observed in any disease category. However, 32% of all patients had pathological antibody titres to at least one ganglioside. Four patients had pathological IgG and IgM titres for all gangliosides evaluated. They suffered from systemic lupus erythematosus [2], neuroborreliosis and schizophrenia, respectively. The results of this study indicate that the introduction of ganglioside antibody determination as a differential diagnostic test in clinical neurology is only helpful in a few patients with typical lower motor neuron syndromes.