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PubMed1994

Highly conserved TCR beta chain CDR3 sequences among immunodominant acetylcholine receptor-reactive T cells in murine myasthenia gravis.

In C57BL/6 (B6) mice, the T cell response to acetylcholine receptor from Torpedo californica (TAChR) provides a specific antibody response and symptoms of muscular weakness similar to those displayed in the human disease myasthenia gravis. We had found previously that the B6 T cell response to AChR shows limited clonality, both in terms of the epitopes recognized and in terms of the diversity of the TCR V beta gene segments used. We now report that all TAChR-reactive B6 T cell clones which responded to the dominant antigenic epitope and expressed the dominant TCR V beta 6 gene segment exhibited conservation of amino acid sequence in the VDJ junctional region (CDR3) of the TCR beta chain. The conserved sequence motif contained a glutamic acid residue in the CDR3 of TCR beta. Analysis of TCR beta sequences from antigen-primed lymph node cells (LNC) showed a similar enrichment for sequences having a glutamic acid in CDR3, although the overall appearance of the LNC sequences was somewhat more heterogeneous and consistent with a gradual in vitro selection of the subset of TCR found in the T cell clones. As the first example of TCR sequences in this model of myasthenia gravis, these results begin to provide a context for understanding self-non-self discrimination of AChR. In particular, the unusually conserved CDR3 sequence suggests that the conserved V beta gene utilization seen previously is directly related to recognition of the immunodominant peptide epitope in association with the experimental autoimmune myasthenia gravis-susceptibility determining MHC class II molecule I-Ab.

Amino Acid Sequence↗

PubMedDate not supplied

Inheritance of congenital myasthenia gravis in smooth fox terrier dogs.

The phenotypes with respect to congenital myasthenia gravis of 132 smooth fox terrier dogs from 25 matings were analyzed. These included both prospective and retrospective matings. It was determined that congenital myasthenia gravis in the smooth fox terrier dog breed is inherited in an autosomal recessive manner with complete penetrance. We propose the symbol mg for the gene for congenital myasthenia gravis in the smooth fox terrier. Attempts to maintain live affected dogs to adulthood were unsuccessful and it is concluded that this is a lethal trait.

Animals↗

PubMed1995

D-penicillamine-induced myasthenia gravis: diagnosis obscured by coexisting chronic obstructive pulmonary disease.

D-penicillamine, a drug used to treat rheumatoid arthritis, Wilson's disease, and cystinuria, can cause myasthenia gravis. Fortunately, the myasthenia typically resolves after discontinuation of the drug. The diagnosis may be missed if weakness is blamed on a patient's underlying disease(s), in particular, rheumatoid arthritis. Reported here are the cases of two patients with chronic obstructive lung disease who were taking D-penicillamine for rheumatoid arthritis, then experienced increasing respiratory failure. At first, their problem seemed to stem from chronic lung disease, but further evaluation revealed the cause of the hypoventilation to be D-penicillamine-induced myasthenia gravis.

Aged↗

PubMed1991

Thymolipoma in association with myasthenia gravis.

A 52-year-old male presented with an anterior mediastinal tumor associated with a 2-year history of myasthenia gravis. The patient underwent thymectomy and a 185-g, 10 X 8 X 3.5 cm, well-delineated tumor was resected. On histologic examination the tumor proved to be a thymolipoma composed of mature adipose elements containing cords and nests of thymic tissue. The latter consisted mainly of cortical areas, the thymocytes of which displayed an immunohistochemical profile of cortical cells, i.e., CD 1+, CD 4+, CD 8+, and frequently Ki 67+. Ultrastructural study confirmed the predominant cortical differentiation of the thymic component. No germinal centers, dendritic reticulum cells, or myoid cells were detected by histologic, immunohistochemical, and ultrastructural studies. The association of thymolipoma with myasthenia gravis is rare; this case is the 10th reported. Our findings lead us to believe that (a) the cortical differentiation of the thymic component and the active thymocyte proliferation could represent a factor leading to myasthenia gravis; and (b) thymolipoma could be a peculiar form of thymoma rather than a mixed tumor of mesenchymal and entodermal origin, a lipoma, or a hamartoma of the thymic gland. The reported association of thymolipomas with other immune disturbances or with neoplastic conditions usually associated with true thymomas support these findings.

Antibodies, Monoclonal↗

PubMed1980

Prediction of the need for postoperative mechanical ventilation in myasthenia gravis.

In order to determine predictors for the postoperative need of mechanical ventilation in patients with myasthenia gravis undergoing thymectomy, the authors retrospectively applied multivariate discriminant analysis to preoperative physical, historical, and laboratory data of 24 myasthenic patients. They identified four risk factors--duration of myasthenia, respiratory disease, pyridostigmine dosage, and vital capacity--that allowed prediction of which patients would need postoperative mechanical ventilation and which could readily have their tracheas extubated. The four factors were weighted according to their respective importance in making this prediction and combined to form a preoperative scoring system. Using the resultant scores for each patient, the authors correctly predicted ventilatory need in 91 per cent of the patients, and only conservative errors (predicting the need for ventilatory support) were made. Traditionally used criteria for evaluating myasthenic patients were poorer predictors than the four factors identified by the authors. The scoring system may be clinically useful in the preoperative evaluation and postoperative care of the patient with myasthenia gravis, for its identifies important variables in the evaluation of the myasthenic patient and serves as an aid to the physician in identifying those able to tolerate early tracheal extubation.

Adult↗

PubMed1987

Aggressive surgical approach for drug-free remission from myasthenia gravis.

A series of 27 patients with generalized myasthenia gravis is presented. All patients were treated by a sternal split and extended thymectomy and radical mediastinal dissection. The overall drug-free remission rate was 63%, although three additional patients are likely to achieve drug-free remission in the near future, with the total drug-free remission rate then being 74%. Of the remaining patients, all but three improved and require decreased medication, for an improvement rate of approximately 90%. One patient who has not improved had an invasive malignant thymoma. Drug-free remission was achieved in 46% of the male patients and in 82% of the female patients despite that the mean duration of disease was greater than 3.5 years. There was one serious complication, that of sterile sternal dehiscence. There was no mortality. The results suggest that an aggressive, radical surgical approach to myasthenia gravis, even in a group of patients considered somewhat less favorable because of a relatively long duration of disease, can result in a high percentage of drug-free remissions. Radical surgery for myasthenia gravis appears to be the treatment of choice, with medical therapy being reserved for those patients who are not likely to survive operation.

Adolescent↗

PubMed1987

Effects of thymectomy in myasthenia gravis.

Factors influencing onset of remission in myasthenia gravis were evaluated in 2062 patients, of whom 962 had had thymectomy. Multivariate analysis showed that appearance of early remissions among all patients was significantly and independently influenced by thymectomy, by milder disease, and by absence of coexisting thymomas. Patients with mild generalized symptoms treated with thymectomy reached remission more frequently, even when compared with those with ocular myasthenia treated without surgery. Short duration of disease before thymectomy in mild cases was another factor associated with earlier remissions. Mortality for all patients was significantly and independently influenced by severity of symptoms, age, associated thymomas, and failure to remove the thymus. Patients without thymectomy and with thymomas had, in addition, earlier onset of extrathymic neoplasms. Morbidity after the transcervical approach was minimal. This study demonstrates that early thymectomy by the transcervical approach, when technically feasible, has significant clinical advantages over the transthoracic approach and should be advocated for all patients with myasthenia gravis, including those with ocular disease.

Evaluation Studies as Topic↗

PubMed1996

Long-term outcome and quality of life after thymectomy for myasthenia gravis.

OBJECTIVE: The authors identify criteria suitable to predict long-term clinical improvement and evaluate quality of life after thymectomy for myasthenia. DESIGN: Retrospective analysis with long-term follow-up (mean 92 months) was conducted for 86 patients and questionnaire interviews were performed for 65 patients who underwent thymectomy between 1976 and 1993. MAIN OUTCOME MEASURES: The authors used the Osserman Score and the European Organization for Research and Treatment of Cancer quality-of-life questionnaire. RESULTS: After thymectomy, lasting benefits were achieved predominantly by patients with moderate and severe myasthenia, and this association was significant (p < 0.001) in both bivariable and multiple analyses. No correlation was observed between outcome and thymic pathology, patient age or gender, duration of disease, preoperative plasmapheresis, and medication. Restitution to normal was complete at most recent follow-up as to physical status, working ability, and cognitive and social functions, but some emotional and vegetative deficits remained. CONCLUSION: Future patient selection for thymectomy should-apart from those with suspected thymoma-concentrate on patients with moderate and severe myasthenia unresponsive to conservative management.

Adult↗

PubMed1993

Myasthenia gravis and pregnancy.

Pregnancy is certainly an option open to patients with myasthenia gravis. Preconceptional counseling is the ideal, with the goal of discontinuing or reducing corticosteroid medications in patients requiring those agents. Alterations in physiology will require ongoing and careful assessment of the pregnant myasthenic or cholinergic crises. Antenatal testing for fetal well-being may be difficult to interpret. A small number of fetuses with fetal myasthenia gravis will be diagnosed by ultrasound. Attempts may be made to decrease the amount of circulating antibody crossing to the fetus. Interventions may include starting or increasing corticosteroid therapy, therapy with azathioprine, or plasmapheresis. Thymectomy is usually not performed during pregnancy. The intrapartum period will increase fatigue in the mother and may precipitate a myasthenic crisis. Epidural anesthesia is currently the agent of choice for decreasing pain and fatigue. An outlet forceps or vacuum delivery will shorten the second stage of labor in those patients who are unable to push repetitively. Cesarean delivery is preferably avoided in those patients at risk for pulmonary and thrombo-embolic complications. Narcotic and sedative medications may be used in the presence of careful and continuous assessment; they may increase respiratory and muscular symptoms. The postpartum period may be associated with an increase in exacerbations. Support services may help to eliminate or to reduce potent stressors during this time. Medication dosages may need to be adjusted as the mother's body returns to her prepregnant state. Transient, neonatal myasthenia is seen in up to 21% of maternal myasthenic cases, even in those patients with no detectable circulating antibody.

Adrenal Cortex Hormones↗

PubMed1983

Myasthenia gravis and pregnancy: a reappraisal of thymectomy.

A retrospective review of pregnancy in patients with myasthenia gravis at Duke University was conducted. Twelve new cases of pregnancy in eight myasthenic mothers are reported. In general, thymectomy was the primary treatment modality in these patients and preceded the gestational period in all cases. The clinical course of myasthenia gravis in these pregnancies prompted a literature review of previous case reports. Comparison of clinical symptomatology, course of disease, and maternal and perinatal morbidity and mortality revealed that the incidence of clinical exacerbation was less in the thymectomy than in the nonthymectomy group. The role of the thymus in the pathogenesis of myasthenia gravis is reviewed. The rationale for the use and timing of thymectomy in the treatment of the myasthenic patient is presented. This review supports the continued use of thymectomy for the initial treatment of the young, nonpregnant myasthenic female patient.

Adolescent↗

PubMed1980

Coexistence of systemic lupus erythematosus and myasthenia gravis.

The coexistence of myasthenia gravis and systemic lupus erythematosus in a 52-year-old woman is reported. Review of the literature shows that systemic lupus erythematosus occurs much more often in the myasthenia gravis population than in the population in general. Myasthenia gravis should be considered in the differential diagnosis in a patient with weakness and systemic lupus erythematosus.

Diagnosis, Differential↗

PubMedDate not supplied

Pericarditis in myasthenia gravis.

Myasthenia gravis is an autoimmune disorder with antibodies to the acetylcholine receptors (Ach R) in skeletal muscles. Myocardial involvement can present as a myocarditis or with arrhythmias. To our knowledge, there is no documentation in the literature of pericardial involvement in myasthenia gravis. We report the presence of pericardial effusion and atrioventricular conduction block in a patient with myasthenia gravis that responded appropriately to immunosuppressive therapy and plasma exchanges.

Heart Block↗

PubMed2002

Anti-p110 autoantibodies identify a subtype of "seronegative" myasthenia gravis with prominent oculobulbar involvement.

Myasthenia gravis (MG) is an autoimmune disease characterized by muscle weakness and pathogenetic autoantibodies directed against the nicotinic acetylcholine receptor (seropositive myasthenia gravis; SPMG). Nearly 15% to 20% of MG patients do not have these antibodies (seronegative myasthenia gravis; SNMG), but several evidence indicate that these patients have circulating pathogenic autoantibodies directed against other muscle antigens. Using the TE671 rhabdomyosarcoma cell line as an antigen source, we analyzed sera from 63 SNMG and 26 SPMG patients and 26 healthy blood donors by FACS analysis. We found that 40 of 63 SNMG patients and only 1 of 26 SPMG patients had IgG binding to the TE671 cell line. None of the sera bound to the unrelated MRC5 cell line. To identify the antigen, we analyzed sera immunoreactivity in more detail by immunoprecipitation of biotinylated membrane proteins from TE671 cells. When the immunoprecipitated proteins were separated by SDS-PAGE electrophoresis and then transferred to nitrocellulose membranes, we found that SNMG IgG identify a band corresponding to a protein with a molecular weight of 110 kDa (P110), which is not recognized by seropositive MG sera. This anti-P110 immunoreactivity is significantly associated with a distinct clinical picture characterized by a prominent involvement of ocular and bulbar muscles, with frequent respiratory problems (p < 0.005), and is recognized by a specific antimuscle specific kinase (MuSK) antiserum. In a recent article, the presence of anti-MuSK antibodies was described in SNMG. Our results confirm the presence of these antibodies in SNMG and suggest that anti-P110/MuSK autoantibodies identify a subtype of SNMG in which the different pathogenesis induces the distinct clinical picture.

Adolescent↗

PubMed2006

Extrathymic tumors in patients with myasthenia gravis: a 35-year retrospective study.

OBJECTIVE: Autoimmune diseases are frequently associated with malignant tumor. In addition, prolonged immunosuppression may favor the development of malignancy. While the coincidence of myasthenia gravis and extrathymic tumor has been reported, the risk and features of these tumors are not well understood. REVIEW SUMMARY: We treated 305 patients with myasthenia gravis from 1968-2003, including 48 thymoma cases. Two hundred twenty-nine patients had undergone thymectomy and 76 had not. We examined cancer risk, tumor characteristics, and associations to medications. We encountered 9 cases of extrathymic tumor. Cancer risk in the thymoma cases was 6.3% and 2.3% in the nonthymoma cases, a statistically insignificant difference. Azathioprine was administered to only 14 in this series of patients; however, 2 patients developed cancer. CONCLUSIONS: Cancer risk in patients with myasthenia gravis is 2.6%, similar to that of the general population in Japan. We neurologists need to be aware that prolonged immunosuppression may favor the development of malignancy.

Adult↗

PubMed2000

A case of linear scleroderma and myasthenia gravis.

We report a case of a 28-year-old woman with myasthenia gravis who developed linear scleroderma seven years later. Myasthenia gravis and scleroderma are rarely found in direct association with each other; there are only five such reported cases, all of which were systemic scleroderma patients. Although localized and systemic scleroderma are distinct entities, autoimmunity is believed to be involved in the pathogenesis of both. Myasthenia gravis and scleroderma may occur coincidentally, but an autoimmune predisposition seems to be the more likely underlying cause, as evidenced by an increased incidence of autoantibodies and autoimmune diseases.

Adult↗

PubMed2005

Circulating and thymic CD4 CD25 T regulatory cells in myasthenia gravis: effect of immunosuppressive treatment.

Accumulating evidence indicates an immunosuppressive role of the thymus-derived CD4+ T-cell population constitutively expressing high level of CD25, T regulatory (Treg) cells, in autoimmune diseases. Here we show that the number of Treg cells in the blood is significantly lower in untreated myasthenia gravis patients than in age-matched healthy subjects, whereas it is normal or elevated in patients on immunosuppressive therapy (prednisone frequently associated with azathioprine). Therapeutic thymectomy (Tx) for either the thymoma or non-neoplastic thymic alterations that are often associated with myasthenia gravis provided unique material for studying intrathymic Treg cells and correlating them with their peripheral counterparts. We observed that Tx prevents the increase of Treg cells in the circulation that follows immunosuppressive therapy (particularly evident if the thymus is not neoplastic), indicating that the thymus contributes to Treg-cell normalization. However, thymic Treg cells are not modulated by immunosuppressive therapy and even in thymectomized patients Treg-cell numbers in the blood eventually recover. The present findings suggest that a deficiency in Treg cells favours the development of myasthenia gravis and that their normalization is an important clinical benefit of immunosuppressive therapy. Treg normalization appears to be largely thymus independent and possibly reflects the reported capacity of corticosteroids to promote Treg-cell development.

Adolescent↗

PubMed1981

Anti-idiotypic antibodies against the receptor antibodies in myasthenia gravis.

Anti-idiotypic antibodies were prepared against purified acetylcholine receptor antibodies from two patients with myasthenia gravis. The purified idiotypes did not cross-react. Reaction with idiotypes from other patients were found in 8% and 37%, respectively, which suggests that shared idiotypic specificities occur. The anti-idiotypic IgG fractions had no receptor-like activity and did not bind cholinergic ligands. Receptor antibodies from two mothers and their newborn children with neonatal myasthenia gravis showed marked differences in the reactions with an anti-idiotypic antibody. This suggests that not passive transfer of maternal antibodies but a transient synthesis of a receptor antibody with a different specificity is an important factor in the pathogenesis of neonatal myasthenia gravis.

Atropine↗

PubMed1998

Myasthenia gravis with alopecia totalis.

Myasthenia gravis was diagnosed on the basis of a positive Tensilon test in a 4-year-old male child with alopecia totalis. His scalp hair and eyebrows had began to disappear at the age of 10 months. No other physical abnormalities such as motor paralysis, were seen except for left ptosis and alopecia totalis. His serum titer of anti-acetylcholine receptor antibody was elevated. No immune system abnormalities (C3, C4, CH50, C-reactive protein, antinuclear antibody or lymphocyte function disorders) were detected. Although alopecia areata and alopecia totalis are sometimes present in adults with autoimmune diseases and myasthenia gravis, this association is rare in children. The present case represents the youngest patient with myasthenia gravis associated with alopecia totalis.

Alopecia↗