N. E. Gilhus

Titin Antibodies in Patients with Late Onset Myasthenia Gravis: Clinical Correlations

We have tested sera from 21 thymectomized patients with onset of MG after 40 years of age and without thymoma for antibodies against titin, using ELISA with the titin peptide MGT-30. Titin is a myofibrillar protein unique to striated muscle and important for the elastic recoil of muscle cells. Titin antibodies were detected in 9 of the 21 sera. MG symptoms as assessed by a 6 point disability score (0-5) were significantly more severe in the titin antibody positive patients both at peak of illness; 3.7 vs. 3.1 (p < 0.02) and at latest follow up; 2.1 vs. 0.8 (p < 0.01). All titin antibody positive patients were on immunosuppressive drug treatment at least follow-up, whereas only 3 of 12 patients without titin antibodies used immunosuppressive drugs. The presence of circulating titin antibodies in late-onset non-thymoma MG patients indicates a more severe disease.

Myasthenia gravis patients with a thymoma have antibodies against a high molecular weight protein in sarcoplasmic reticulum

Our purpose was to investigate whether components of the sarcoplasmic reticulum (SR) are relevant antigens in myasthenia gravis (MG). Using enzyme-linked immunosorbent assay (ELISA), 75 MG sera and 120 control sera were examined for IgG antibodies against SR prepared from rabbit skeletal muscle. 16/30 thymoma MG patients had IgG antibodies that reacted with SR. 1/30 MG patients with thymic hyperplasia and 3/15 MG patients with thymic atrophy had SR antibodies in low concentrations. Control sera were negative. Using immunoblot, SR antibodies were detected in the thymoma group only. 14/30 sera from thymoma patients reacted with a protein of 320 kDa relative molecular weight. The only reported SR protein with similar electrophoretic mobility is the subunit of the spanning protein which links junctional SR to sarcolemma and functions as a calcium-release channel.

Ryanodine receptor antibodies are associated with severe myasthenia gravis

Sera from 32 thymoma patients, 29 of them with myasthenia gravis (MG), were tested for the presence of circulating antibodies to the ryanodine receptor (RyR) in Western blot RyR is a channel protein essential for the excitation‐contraction coupling in skeletal muscle. MG severity was scored according to the Osserman classification during 1–17 years of follow‐up (mean 7 years). Fifteen patients (14 MG and 1 non‐MG) were RyR‐antibody positive. RyR‐positive patients had a significantly higher frequency of invasive thymomas (p = 0.01), and also a more severe MG than RyR‐antibody negative patients (p = 0.04). The use of immunosuppressive drugs at latest follow‐up was more frequent in RyR‐antibody positive than in RyR‐antibody negative patients (p = 0.02). Thus the presence of RyR‐antibodies in thymoma patients is associated with a more severe disease and can be used as a prognostic marker.

Cell‐Mediated Immune Response Against Titin in Myasthenia Gravis: Evidence for the Involvement of Th1 and Th2 cells

Myasthenia gravis (MG) patients may have circulating autoantibodies against titin. In this study, we have stimulated T cells from MG patients with a recombinant polypeptide containing the main immunogenic region of titin, MGT‐30 (myasthenia gravis titin‐30 kDa). In an ELISpot assay, MGT‐30 reactive interferon (IFN)‐γ secreting cells (Th1 cells) were detected in six of 10 titin antibody positive MG patients. Such cells were not detected in any of the five titin antibody negative MG patients or in the seven blood donors. In three patients, the stimulated number of cells decreased when total remission of MG symptoms was achieved after thymectomy or following a period of intensive immunosuppressive medication. We detected MGT‐30 interleukin (IL)‐4 secreting cells (Th2 cells) in two of five titin antibody positive MG patients, but not in the two titin antibody negative patients or the five blood donors examined. We conclude that titin antibody positive MG patients have a combined Th1/Th2 cell mediated immunity against the muscle protein titin.

Open Facilities for Training in European Neurology (OFTEN): a European Board of Neurology initiative

The European Board of Neurology has established Open Facilities for Training in European Neurology (OFTEN) by creating a databank of excellent or good neurological departments from 14 European countries willing to receive trainees from abroad (http://www.uems.be/neuro.htm). Further expansion of this databank with an increased number of participating departments and countries is planned. The databank should make it easier both to find a relevant department for training abroad and to obtain funding from various sources. No financial support is available in the program itself. The ultimate aim of this cross‐European training is to improve neurological skill, knowledge and attitude. It will also promote European co‐operation and harmonization in quality of care.

Titin antibody positive myasthenia gravis patients have a cellular immune response against the main immunogenic region of titin

Some myasthenia gravis (MG) patients have antibodies against non‐acetylcholine receptor (AChR) epitopes of skeletal muscle including titin. Peripheral blood lymphocytes from 11 MG patients and 13 blood‐donors were tested for lymphocyte proliferation after stimulation with the titin peptide MGT‐30, which represents the main immunogenic region. Four out of seven titin antibody positive patients had significant stimulation defined as a stimulation index (SI) above 2. Neither of the four titin antibody negative patients nor the 13 blood‐donors had SI above 2 (p = 0.001). Mean SI was significantly higher for T‐cells from titin antibody positive MG patients, SI = 2.2 ± 0.8, compared to titin antibody negative patients, SI = 0.9 ± 0.2 (p = 0.01), and blood‐donors, SI = 0.8 ±0.3 (p > 0.0005). After MGT‐30 stimulation, IL‐4 was detected in the blood lymphocyte culture supernatant from four of the five MG patients examined, but from none of the eight blood‐donors. Thus, MG patients with anti‐titin antibodies have a T‐cell mediated immune reaction against titin.

Thymic lymphoepitheliomas and skeletal muscle expressing common antigen(s)

Rabbit antiserum to a citric acid extract of human skeletal muscle (CA) stained epithelial thymoma cells as well as skeletal muscle. Thymomas from two myasthenia gravis (MG) pàtients showing no circulating anti‐CA antibodies prior to thymectomy were also stained by the antiserum. Thus, in these patients as well, the thymoma and skeletal muscle possess common antigens. The rabbit and the human antibodies most probably reacted with different antigens, apparently located close to each other in the cell membrane. The reason why anti‐CA antibodies cannot be detected in serum from a few MG patients with a thymoma may be that the thymoma‐associated antigen is not present in vivo in these cases, or that an inhibiting factor blocks the antibody synthesis. Both patients developed anti‐CA antibodies post‐operatively, which favours the latter explanation.

Myasthenia gravis muscle antibodies examined by ELISA : IgG and IgM antibodies characterize different patient subgroups

Sera from 90 myasthenia gravis (MG) patients were examined for antibodies against skeletal muscle citric acid extract (CA) antigens by ELISA and indirect haemagglutination (IHA). 31% (ELISA) and 24% (IHA) of the sera were positive, and the results of the two tests were in good agreement. 18 of 28 patients positive in ELISA had IgG CA‐antibodies, 10 had IgM and 3 IgA CA‐antibodies. The patients with IgG antibodies had a high mean age of MG disease onset, and 9/14 thymectomized patients had a thymoma. Patients with IgM CA‐antibodies had a much lower age of onset and 4/5 thymectomized patients had thymus hyperplasia. IgM antibody positive patients had a long disease duration, indicating that they produce IgM antibodies for an indefinite period of time without switching to IgG antibody production.

Task force on minimum standards for health care of people with multiple sclerosis: June 1999

M. P. Barnes, N. E. Gilhus and M. Wender On behalf of the EFNS Scientist Panels on Neurorehabilitation, Neuroimmunology and Demyelinating Disease University of Newcastle upon Tyne, Hunters Moor Regional Neurorehabilitation Centre, Hunters Road, Newcastle upon Tyne, UK; Department of Neurology, University of Bergen, Haukeland Hospital, Bergen, Norway; and Neuroimmunological Unit, Medical Research Centre, Polish Academy of Science, Poznan, Poland

Accessory Molecule Expression in Human Thymomas and Thymus

Paraneoplastic MG is probably caused by sensitisation of T-cells to muscle-like epitopes presented on the neoplastic epithelial cells. Accessory molecules on antigen-presenting cells and T-cells are important for the outcome of the immunisation process. In this study, cryostat sections from 13 thymomas (11 with MG, 2 without; 10 non-invasive, 3 invasive; 3 spindle-cell, 10 polygonal-cell thymomas) and 6 normal thymuses from children were examined for the accessory molecules ICAM-1, VCAM-1, LFA-3 and CD28 using commercially available mouse monoclonal antibodies and immunoperoxidase staining.