Combined features of myasthenia gravis and Eaton-Lambert syndrome: anti-ganglioside antibodies in serum

Antiganglioside antibodies and paraneoplastic neuromuscular junction disorder?

Based on the instructions in “Guide for authors”, our manuscript is a case reports and was submitted under “Letters to the Editor”, which should not include an abstract.

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Antiganglioside antibodies in paraneoplastic neuromuscular junction disorders.

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Antiganglioside antibodies binding receptors at neuromuscular junction motor nerves terminal.

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Electrophysiological evidences of neuromuscular transmission defect in presence of antiganglioside antibodies.

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Respond to immunotherapy of paraneoplastic neurological symptoms in advance to treatment of underlying malignancy.

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The necessity of malignancy and paraneoplastic work up in seronegative new onset neuromuscular junction disorders.

Factors affecting the fine specificity and sensitivity of serum antiganglioside antibodies in ELISA

The major problem associated with ELISA of serum antiganglioside antibodies is the high background values (absorbancy of sera added to wells without ganglioside), which interfere with the accurate assessment of the fine specificity and sensitivity of these antibodies. This investigation identifies factors elevating the background values and/or decreasing the fine specificity, and describes strategies to minimize their influence. Using sera of neuropathy and melanoma patients, we found that highest background values were observed with the polystyrene 'tissue culture' microtiter plates; of the various 'non-tissue culture' microtiter plates tested, the lowest background values (> 0.060) were observed with Costar-3590 (H), Immunolon-3, Immunolon-1, Falcon-3915 (in increasing order). Background artifact of polystyrene microtest plates was significantly reduced by gamma irradiation (at 40 kRad) and/or use of detergent Tween-20 (0.1%) in the washing step. Even after controlling the background values, the fine specificity, namely, the ability of the antibody to distinguish between the target epitope of an antigen and epitopes of related antigens (when moles of antigen/well is constant) varied with different microtiter plates. Using sera with high affinity and specificity for GM2, GD3 or GM3, we observed that Immunolon-1, Immunolon-3 and particularly Falcon-3915 were superior for assessing the abilities of the antibodies to distinguish closely related epitopes found on other gangliosides. The reactivity of antiganglioside antibodies was more consistent after detergent treatment. The reactivity of antibodies to GD3 is significantly enhanced after treatment with Tween-20, but that of antibodies reacting to GM1 and GM2 is reduced. Fine specificity of the antiglycolipid antibodies was resolved better by coating glycolipids in mol/well rather than by weight/well. Based on these results, a protocol for a sensitive and reproducible ELISA for serum antiganglioside antibodies is recommended. The protocol takes into consideration the suitability of polystyrene plates, coating based on the number of molecules, pertinency of the solvent for coating, use of human serum albumin for blocking, dilution and washing steps and use of 0.1% Tween-20 to further minimize the background absorbancy.

Antiganglioside antibodies in patients with neuropsychiatric systemic lupus erythematosus

Antiganglioside antibodies (AGA) were determined in sera and cerebrospinal fluids (CSF) from 50 systemic lupus erythematosus (SLE) patients, and age-matched normal controls. The SLE patients were subdivided according to the type of clinical manifestation into two groups: neuropsychiatric SLE and active SLE without neuropsychiatric manifestation. The presence of these antibodies showed a significant correlation between IgG AGA in the CSF and IgM AGA in the serum and neuropsychiatric SLE. Fifteen patients had this antibody in the CSF without detectable levels in the serum. No correlation was seen between anticardiolipin antibodies in the serum of CSF and neuropsychiatric SLE. The present work suggests that antibodies against gangliosides may be a marker for neuropsychiatric SLE and that intrathecal antibody production can result in the development of this manifestation.

[Electrophysiologic data on myasthenic syndromes of the Lambert-Eaton type. A series of 23 cases]

The electrophysiological data of 23 adult patients with Lambert-Eaton myasthenic syndrome (LEMS) have been reviewed. Lung carcinoma was disclosed in 17. In six cases with an EMG follow-up ranging between one and 17 years no carcinoma was detected. The results of repetitive nerve stimulation test (RNS) were not statistically different between the 2 groups. Low CMAP ulnar amplitude was present in all patients (mean: 1.7 mV). Decremental response at low rate of stimulation (3 Hz) was present in 17/20 (means: 30%). An abnormal incremental response at high rate of stimulation was present in all cases (mean: 826%). The authors emphasize the interest of a 50 Hz stimulation for 4 s. Increase of the 'F-wave' amplitude was noticed in some cases. Electrophysiological changes suggestive of an associated mild neuropathy were noticed in eight patients but H-reflex was present in 3/3 cases. SFEMG abnormalities were found in 6/6 cases. In one case, stimulated SFEMG showed more blockings and an increased jitter with low rate of stimulation. In one case the electrical pattern of RNS could be misinterpreted as myasthenia gravis in one tested muscle only. The author's results suggest that CMAP amplitude and RNS test could be used to appreciate the short-term improvement of LEMS with treatment and in some cases for the long-term follow-up.

Effect of thymectomy and immunosuppressive therapy on anti-neuroblastoma antibody levels in patients with myasthenia gravis

Antibodies reacting with human neuroblastoma cells (NBL) are distinct from the "classical" anti-acetylcholine receptor (AChR) antibodies in myasthenia gravis (MG). The influence of therapeutic interventions on serum anti-NBL antibody levels was followed in 42 MG patients. Thymectomy alone was performed in 28 patients while immunosuppressive medication was given to 14 patients out of whom 10 also had a thymectomy. In most patients serum anti-NBL antibody titers declined after thymectomy and/or during immunosuppressive treatment, though individual variations in the antibody response could be observed. Sequential examinations of individual patients revealed an association between the clinical severity of MG and anti-NBL antibody levels. No correlation between the treatment-induced changes of anti-NBL and anti-acetylcholine receptor (AChR) antibody titers could be observed during the follow-up period in MG patients positive for both types of antibodies. These findings further emphasize the immunological complexity of MG. Anti-NBL antibodies represent a pathogenic marker of the disease and display a regulation different from that of the anti-AChR antibodies.

Anti-neuroblastoma antibodies in myasthenia gravis: clinical and immunological correlations

Forty-four of 109 myasthenia gravis (MG) patients (40%) had serum antibodies against human neuroblastoma cells (NBL). Anti-NBL antibodies were most frequent in the sera of MG patients who had either a hyperplastic thymus or a thymoma, clinically mild to moderately severe generalized MG, and a long disease duration (greater than or equal to 11 years). No correlation between individual anti-NBL antibody and anti-acetylcholine receptor (AChR) antibody titers was observed. Seven of the 19 patients negative for anti-AChR antibodies (37%) had anti-NBL antibodies in their sera. These findings provide further evidence for immunological heterogeneity in MG. In addition to the typical autoantibodies to the AChR, autoimmunization against neural antigens can frequently be detected in these patients.