Myasthenia gravis as an autoimmune disease: clinical aspects

Acute presentation of autoimmune hepatitis in a patient with myasthenia gravis, thymoma, Hashimoto thyroiditis and connective tissue disorder

Myasthenia gravis is an antibody-mediated autoimmune disease at the neuromuscular junctions. It can be associated with many other autoimmune diseases. We report a case of acute presentation of autoimmune hepatitis with myasthenia gravis, thymoma, Hashimoto thyroiditis and connective tissue disorder.

Chronic myeloid leukemia in myasthenia gravis after long-term treatment with 6-mercaptopurine

A woman with myasthenia gravis and a thymoma did not respond sufficiently to thymectomy. She was treated with 6-mercaptopurine. Withdrawal of this treatment was several times followed by an aggravation of myasthenic symptoms. After more than 12 1/2 years treatment she developed Ph1-positive chronic myeloid leukemia (CML). No other case of CML following immunosuppressive treatment has been described. Because the therapeutic agent is potentially leukemogenic, the possibility cannot be definitely excluded that the development of CML is not a mere coincidence.

Treatment Principles in the Management of Autoimmune Myasthenia Gravis

The pathogenesis of myasthenia gravis (MG) involves a T cell-directed antibody-mediated autoimmune attack on the nicotinic acetylcholine receptor (AChR) or, occasionally, on other postsynaptic antigens. The antibodies induce their effects through complement-mediated destruction of the postsynaptic endplate membrane with resultant reduction in endplate AChR, and to a lesser degree by increased turnover of endplate AChR or blockade of AChR function. Considerable progress in the treatment of MG has accrued from so-called symptomatic treatments, including improved critical care of seriously ill patients and medications (e.g., cholinesterase inhibitors) increasing the concentration of acetylcholine at the remaining endplate AChRs. Information from other autoimmune diseases and from the response of the normal immune system to invading pathogens supports the view that the course of MG is characterized by exacerbations and remissions. Therefore, the goal in MG treatment is to induce and maintain a remission. This usually involves combinations of short-term and long-term immunosuppressive agents. Selection of the particular combinations of agents in a given patient is guided by the goal of minimizing the cost/benefit ratio of the regimen in an individual patient. In general, the plan involves an initial forceful attack followed by a slow and measured withdrawal.

Autoimmune Disorders of Neuronal Potassium Channels

Antibodies to voltage-gated potassium channels (VGKCs) appear likely to be the effector mechanisms in many patients with acquired peripheral nerve hyperexcitability (APNH) syndromes, a group of disorders that include neuromyotonia, cramp-fasciculation syndrome, and Isaacs' syndrome. They may contribute to the associated autonomic changes. Through a central action, they may also be the effector mechanism in those with Morvan's syndrome and in some patients with limbic encephalitis. Evidence supporting this hypothesis includes the increased association of APNH with autoimmune diseases (in particular, myasthenia gravis and thymoma), the response to plasmapheresis, passive transfer of APNH to experimental animals by patients' plasma or immunoglobulins, the action of their serum on VGKC currents studied in vitro, and the presence in many patients of IgG antibodies to VGKCs.

Myasthenia gravis with ocular involvement in older patients

BACKGROUND

There has been little previous study reporting the eye findings and presentation of elderly patients with myasthenia gravis. The purpose of this study was to review the findings and course of myasthenia gravis after the sixth decade of life.

METHODS

Retrospective observational case series. The authors reviewed the clinical records of 27 patients with onset of myasthenia gravis at age 60 years or more who were seen at a tertiary care academic ophthalmology centre in Houston between January 1992 and March 1999. The diagnosis of myasthenia gravis was based on conventional clinical and laboratory criteria.

RESULTS

Twenty patients (74%) were men. Of the 16 patients who underwent testing for anti-acetylcholine receptor antibodies, 11 (69%) were seropositive. Concurrent thyroid disease was found in seven patients (26%), including five (71%) of the seven women. No patient had thymoma. Sixteen patients (59%) manifested generalized symptoms during follow-up; 12 did so within 1 year of disease onset. Patients responded well to both anticholinesterase and corticosteroid therapy. At the most recent follow-up visit 18 patients (67%) were clinically improved, and no patient was clinically worse.

INTERPRETATION

Myasthenia gravis in this study was characterized by a male predominance, high rate of concurrent thyroid disease, high rate of progression to mild generalized symptoms, absence of thymoma, good response to medical therapy and minimal life-threatening complications. Clinicians should consider the diagnosis of myasthenia gravis in an older patient presenting with diplopia or ptosis.

Myasthenia gravis and associated autoimmune diseases in children

Myasthenia gravis has been associated with other autoimmune disorders. We report two children with myasthenia gravis and another autoimmune disease: an 18-month-old boy with ocular myasthenia gravis and Hashimoto's disease and a 14-year-old girl presenting with autoimmune polymyositis, then generalized myasthenia gravis 2 years later. The rare combinations of myasthenia gravis and Hashimoto's disease or polymyositis in children are discussed, and we also briefly review myasthenia gravis and other associated autoimmune diseases in children.

Does myasthenia gravis affect the brain?

Associations between myasthenia gravis (MG) and CNS functions have been made for over 80 years. An increased incidence of psychiatric disorders, epilepsy and multiple sclerosis as well as electroencephalographic (EEG) abnormalities and abnormal evoked responses have been noted in patients with MG. Descriptions of sleep and memory disturbances in MG patients appeared as knowledge accumulated about the role of brain cholinergic systems in sleep and memory. The inference of many of these studies has been that the alleged central cholinergic effects in MG were caused either by the anticholinesterases used to treat MG or by antibodies to muscle nicotinic acetylcholine receptor (nAchR) present in the serum and cerebrospinal fluid (CSF) of MG patients. The antigenic differences between muscle nAchR and neuronal nAchRs, together with the very low concentrations of muscle nAchR antibodies in the CSF, make highly unlikely the claims that CNS cholinergic systems are affected by these muscle antibodies in MG patients. Evoked response abnormalities, if indeed present, are more likely caused by peripheral than central mechanisms, and sleep abnormalities in MG also probably originate in the periphery rather than in the CNS, the result of hypoxia caused by oropharyngeal, intercostal and diaphragmatic muscle weakness which may worsen during sleep, especially during REM sleep. Such hypoxia may account for some of the EEG abnormalities noted in MG patients, but the association of MG with epilepsy appears to be either coincidental or the result of uncontrolled MG. Significant excessive daytime sleepiness resulting from sleep disturbances can also impair memory and the performance of MG patients on neuropsychological tests, as can the presence of mental depression. The psychological aspects of MG can be attributed to the expected consequences of a chronic but unpredictable neuromuscular disease involving weakness of breathing, swallowing, talking, limb and eye movement. Considering the number and variety of claims for direct CNS involvement in MG, the evidence for this is remarkably unconvincing. The quality of MG treatment, both physical and psychological, is a presently undefined variable which might help explain the diametrically opposed results which have been obtained in some of the studies reviewed. Adequate respiratory muscle strength during sleep is an often overlooked peripheral influence upon mental functioning and general well-being of MG patients.

Myasthenia gravis

Adult-onset myasthenia gravis is an acquired autoimmune disorder of neuromuscular transmission in which acetylcholine receptor antibodies attack the postsynaptic membrane of the neuromuscular junction. Although the cause of this disease is unknown, the role of immune responses in its pathogenesis is well established. Circulating acetylcholine receptor antibodies are present in 80% to 90% of patients with the generalized form of myasthenia gravis. Most patients have ptosis, diplopia, dysarthria and dysphagia. The weakness and fatigue worsen on exertion and improve with rest. Respiratory muscle and limb weakness are rare at the onset of the disease. For the past two decades, there has been considerable progress in understanding the diagnosis and management of myasthenia gravis. The diagnosis is based on clinical presentation, neurologic examination, and confirmation by means of electrophysiologic testing and immunologic studies. Myasthenia gravis mimics many neuromuscular diseases and even illnesses such as depression and chronic fatigue syndrome. One should always exclude drug-induced myasthenia gravis for all patients. With the introduction of new modalities of treatment, particularly immunosuppressive or immunomodulating drugs, plasma exchange and thymectomy, the morbidity and mortality of myasthenia gravis have decreased dramatically to the point that myasthenia gravis should not be considered as serious a disease as it once was. Although the several therapeutic options are usually effective and have meant independence in daily life to many patients with myasthenia gravis, well-designed, controlled, prospective studies are still lacking.

Myasthenia gravis in Hong Kong Chinese. 1. Epidemiology and adult disease

A territory-wide study of myasthenia gravis (MG) was conducted in Hong Kong. Two hundred and sixty-two Chinese patients (159 adult and 103 paediatric onset) were identified, corresponding to a point prevalence and period prevalence of 53.5 and 62.2 per million respectively, and an average annual incidence of 4.0 per million population. Nine patients died, 7 from MG, giving a case fatality rate of 0.027. Female predominance was present in the whole group of patients (female to male ratio 1.6:1) and in those with adult disease (ratio 2.1:1), but not in those with onset in childhood (ration 1.1:1). Onset of disease was most common in the first 3 decades of life, and became less common in subsequent decades. Juvenile onset MG occurred in 39.3% of patients and restricted ocular MG in 47.9%. Familial occurrence was found in 5 patients. In the 159 adult onset patients, ocular disease was most common (32.7%), followed by mild generalised (29.6%), moderately severe generalised (24.5%), fulminating (11.9%) and late severe disease (1.3%). The mean age of onset of symptoms was 36.7 years. The symptomatology was similar to that of Caucasoid populations. Autoimmune thyroid disease was the commonest associated disease, and the incidence of thymoma among thymic abnormalities was high at 38%.

Myasthenia gravis and lymphoblastic lymphoma antiacetylcholine receptor antibody as a tumor marker--a case report

This report documents an association between lymphoblastic lymphoma and myasthenia gravis. Elevation of acetylcholine receptor antibody titer was an unusual marker for the lymphoblastic lymphoma. Following chemotherapy all symptoms of myasthenia gravis resolved and the acetylcholine receptor antibody titer normalized. The patient remains in complete remission off all therapy 20 months since the diagnosis of myasthenia gravis was made and 12 months after chemotherapy for her lymphoma.

Association of HLA-DRw9 with myasthenia gravis in Chinese

HLA phenotypes were studied in 59 Chinese myasthenia gravis (MG) patients. Unfractionated peripheral blood mononuclear cells were used for typing of HLA-A, B and C, and B-enriched lymphocytes for HLA-DR. Seventy-nine healthy subjects were included as controls. When compared with healthy controls, the patients showed significant increases in HLA-Bw46 (47.5% versus 14%, chi 2 = 18.7, P less than 0.001), HLA-DRw9 (59.3% versus 11%, chi 2 = 35.7, P less than 0.001), while HLA-DR3 was decreased (3.4% versus 32.9%, chi 2 = 18.2, P less than 0.001). Further analysis showed that the primary association was with DRw9 and the increase in Bw46 was secondary to it. Both HLA-Bw46 and -DRw9 were increased in all subgroups except where the age of onset was greater than 40 years. Finally, the HLA-A2-Bw46-DRw9 combination was also significantly increased in patients (25.4% versus 5.1%, chi 2 = 11.5, P less than 0.001), especially in the subgroups of MG with age of onset of less than 10 and males with age of onset of less than 40 years.

[Acute systemic lupus erythematosus after thymectomy for myasthenia. Sequential study of lymphocyte subpopulations]

A 35 year-old woman developed severe systemic lupus erythematosus 9 years after thymectomy for myasthenia gravis. "Seric Thymic Factor" (STF) was low; T helpers subset, T helpers/T suppressors ratio and to a lesser extent T suppressors subset were decreased. Suppressor cell function investigated by Concanavaline A lymphocyte reactivity was low. Under cyclophosphamide, plasmapheresis and steroids all clinical and biological symptoms improved but STF remained low; T helpers, T suppressors subsets and T helpers/T suppressors ratio increased but did not reach the normal range. Statistical and immunological arguments suggest that the association between systemic lupus erythematosus and myasthenia gravis did not occur only by chance. Moreover, thymectomy might have played a role by decreasing the number and function of some subpopulations of lymphocytes.

The cerebrospinal fluid in myasthenia gravis

We examined the number of leucocytes and the concentration of total protein, albumin and IgG in the cerebrospinal fluid (CSF) from 46 patients with myasthenia gravis (MG) and 50 controls. Mean leucocyte number in the MG patients was 1634 cells/ml (controls 1244), mean total protein 0.38 g/l (controls 0.32), mean IgG 0.034 g/l (controls 0.025) and mean albumin 0.199 g/l (controls 0.176). No evidence of intrathecal IgG synthesis was demonstrated. The CSF was normal in most cases. When pathological changes occurred they were slight and could be attributed to associated diseases or to iatrogenic blood contamination of the CSF. We demonstrated that an artificial blood contamination of the CSF, although macroscopically undetectable, increased the CSF albumin concentration and the CSF albumin/serum albumin ratio considerably.

Cancer risks in patients with chronic lymphocytic thyroiditis

The incidence of malignant tumors and leukemia was analyzed in 829 patients with chronic lymphocytic thyroiditis and in 829 individually age-matched and sex-matched patients with colloid goiter. Diagnoses were based on cytologic studies of specimens obtained by fine-needle aspiration biopsy. The patients were examined between 1959 and 1978 and were followed in the Swedish Cancer Register between 1959 and 1981. There was no increased risk for the total number of tumors in the thyroiditis group (53 observed vs. 52.7 expected) or in the colloid-goiter group (40 vs. 53.2, respectively; P not significant). There were six lung cancers in the thyroiditis group (2.9 expected, P not significant), and one in the group with colloid goiter. Patients with thyroiditis had an increased risk of myeloproliferative and lymphoproliferative neoplasms (12 observed vs. 3.0 expected, P less than 0.001). The risk of malignant thyroid lymphoma was greatly increased, with an estimated relative risk of 67 (4 observed vs. 0.06 expected, P less than 0.000001). There was no increased risk for any type of tumor among patients with colloid goiter.

[Thyroid diseases and myasthenia gravis]

In a group of 304 myasthenic patients 15 cases with thyropathies were reported: nine with hyperthyroidism, one with hypothyroidism and five with nontoxic goiter. Four patients presented diffuse simple goiter and one a multinodular goiter with normal thyroid function. No patient came from an endemic goiter region, not even familial goiter. The prevalence and influence of hyperthyroidism on myasthenic symptomatology were studied. Our findings suggest that there is no clinical correlation between both myasthenia symptomatology and thyroid dysfunction, neither significant influence on myasthenic symptoms when the endocrine disorders improve.

[Diseases and syndromes associated with myasthenia gravis in a group of 304 patients]

Epidemiologic and clinic studies of both diseases and syndromes associated in a group of 304 myasthenic patients were made. A comparative projection between the present cases and those of other authors was presented.

Imbalances in T-cell subpopulations in myasthenia gravis

Distributions of peripheral blood lymphocyte subpopulations and T-cell subsets were studied in 38 patients with myasthenia gravis (MG) and 23 healthy controls. T cells were detected by rosette formation with sheep red blood cells and B cells with erythrocyte-antibody-complement (EAC) complexes. T mu cells were identified by rosette formation of T cells with Ox RBC-IgM complexes, and T gamma cells with Ox RBC-IgG complexes. The means of total lymphocyte count and active T cell percentage were marginally significantly lower in MG patients than in normal controls (0.05 less than P less than 0.1). The mean percentage of T mu cells was higher in MG patients than in controls (50.2 +/- 11.8% vs. 38.5 +/- 15.3%, P less than 0.01), whereas that of T gamma cells in the former was lower than that in the latter (20.4 +/- 7.1% vs. 27.6 +/- 6.2%, P less than 0.001). Thus, the loss of regulatory suppressor T cells and the increase of helper T cells in the patients are in favour of regarding MG as an autoimmune disease. The fact that the percentage of T gamma cells was significantly decreased in MG patients after autologus serum incubation, and that no such a phenomenon was seen in normal controls, may suggest a possible role of serum factors in the pathogenesis of MG.

Current trends in the management of myasthenia gravis: plasmapheresis and immunosuppressive therapy

In recent years a considerable body of evidence has accumulated to demonstrate autoimmune mechanisms in myasthenia gravis. This evidence has important implications for the aetiology, diagnosis and management of the disease. The primary abnormality in myasthenia gravis is related to the presence of antibody which reacts with the acetylcholine receptor. Measurement of this IgG antibody in the serum has become the most reliable diagnostic adjunct to the edrophonium test, and in an individual patient, the level of the serum antibody relates closely to the clinical indices. In cases of myasthenia where control with anticholinesterase drugs is unsatisfactory, methods to lower the antiacetylcholine receptor antibody are indicated: these may include thymectomy, immunosuppressive therapy of plasmapheresis. Two patients with very severe disease are described in whom all types of therapy were used and in whom survival depended ultimately on the use of plasmapheresis. These patients illustrate the importance of receptor antibody in the clinical manifestations of myasthenia gravis and in its management.

Myasthenia gravis with a monoclonal gammopathy--report of a case

An elderly man with relapsing myasthenia gravis was found to have hypergammaglobulinaemia, a monoclonal peak of gamma mobility and paraproteinaemia IgG, type K. Bence-Jones proteinuria, type K was present. This is the fourth report of myasthenia gravis associated with a monoclonal gammopathy. Myasthenia gravis is considered to be an autoimmune disease. Recent findings implicate a dysfunction of cellular immunity in the pathogenesis of both immunoproliferative and autoimmune disease. We suggest that the association of myasthenia gravis and monoclonal gammopathy in our patient might have stemmed from a disorder of T lymphocyte function.

Plasma-exchange combined with immunosuppressive therapy in myasthenia gravis

Twenty-one patients with myasthenia gravis underwent a course of plasma exchange combined with immunosuppressive therapy. In fifteen there was dramatic clinical improvement which has been maintained for periods up to 19 months. Nine of these patients now take no anticholinesterase drugs. Six patients had a recurrence 3--9 months after the first course but in the three given a second course remissions were again obtained.

[Thymectomy in myasthenia gravis. Evaluation of the results in 73 patients]

An evaluation of results obtained after 73 thymectomies is reported. A transthoracic approach was used on all of the patients. Thymomas were found in 9 out of the 73 patients with myasthenia. All of the 64 patients without thymomas suffered from generalized myasthenia gravis with predominance of severe forms. The results of the early, intermediate and late post-operative course were analysed. A comparative study of results as related to age, sex, duration of disease and presence or absence of thymomas was made. Statistical analysis failed to show any significant difference in the results of thymectomy between selected and randomly chosen patients without thymomas.

Myasthenia gravis: a personal view of pathogenesis and mechanism, part 1

A review of our current knowledge of the etiology and pathogenesis of myasthenia gravis is presented, with particular emphasis on the immunological aspects of the disease. Part 1, published in this issue, deals with the clinical and genetic features of myasthenia gravis which led to the autoimmune theory of the etiology of this disease. Various theories in this field are reviewed, and recent advances in our knowledge of the acetylcholine receptor protein, and its immunology, are examined. Part 2, which will appear in the March/April issue, provides a review of the dysfunction of physiology, pharmacology, and structure of the neuromuscular junction in myasthenia gravis, and the part played by the autoimmune process.

Follow-up study of myasthenic children after thymectomy

The results of thymectomy of 28 myasthenic children observed from 1 to 9 years after operation are discussed. Improvement was obtained in 19 cases (67.8%), with full remission in 12 cases (42.8%). Six children died. No correlation was found between the results of thymectomy and the duration of the disease, sex or histological findings in the thymus. No increase of incidence or severity of infections were observed in thymectomized children. Caution is recommended regarding vaccination of myasthenic children.

Assessment of cellular and humoral immunity of myasthenics

A close association of autoimmune diseases or autoimmune phenomena in myasthenia gravis is well known. A comprehensive immunological study of 22 patients with myasthenia gravis showed that changes in the immune system mainly involve the thymus-derived lymphocytes (T cells). Anti-thymus antibody was present in 90% of the patients, and it paralleled the frequency of thymic abnormality in myasthenia gravis. It is postulated that in myasthenia gravis the altered T cell functions caused by anti-thymus antibody result in the formation of an array of autoantibodies including the factor which blocks the neuromuscular transmission.

Leucocyte migration inhibition in myasthenia gravis. The effect of thymectomy

Cellular hypersensitivity in myasthenia gravis (MG) to the thymus, muscles and peripheral nerves was examined by the method of the leucocyte migration inhibition test. The group of MG patients without thymoma had inhibition of leucocyte migration by thymus antigens. After thymectomy, they had a normal value of leucocyte migration. However, in the group of MG patients with thymoma, the inhibition of leucocyte migration by thymus antigens was observed after thymectomy. No significant inhibition of leucocyte migration was observed using muscle and peripheral nerve antigens. Cellular immunity in myasthenia gravis and the pathogenesis of the disease was discussed.

Immunoperoxidase localization of alpha bungarotoxin: a new approach to myasthenia gravis

The IPBT method has made it possible to precisely visualize the AChR. Normal distribution of AChR is at the peaks of the postjunctional folds of the muscle sarcolemmal membrane with a small amount present on the axonal tip as well. Denervated muscle fibers have extrajunctional AChR. In MG, there are also denervated-appearing fibers but these do not have extrajuctional AChR with the IPBT stain. To explain this, we have been able to demonstrate a serum factor capable of blocking the binding of alpha-BuTx to the AChR and have shown for the first time that this factor is capable of acting at the neuromuscular junction itself. This blocking factor may play a major role in causing the weakness of MG.

Immunology and thoracic surgery

This report reviews the current status of three types of diseases in which knowledge of immunology is changing the practice of thoracic surgery. Evidence is presented for myasthenia gravis being an autoimmune disease. Thymectomy is widely considered to be the therapy of choice for patients with generalized myasthenia regardless of age or sex. Opportunistic pulmonary infections of unusual types are being encountered frequently in patients receiving immunosuppressive drugs for organ transplantation or malignancy. The important role of bronchial brushing and open lung biopsy is stressed. Immunotherapy of several types is currently being investigated experimentally and clinically and promises to change therapy for bronchogenic and esophageal neoplasms.

Studies on the nature of autoimmunity in myasthenia gravis. Evidence for an immunodeficiency type

Clinical and laboratory data continue to support the concept of a genetically determined breakdown of immunological tolerance in myasthenia gravis with immunological damage to the motor end plates. The demonstration of impaired function of thymus-derived lymphocytes and of IgA deficiency correlate well with the clinical data in which there is an increase incidence of autoimmune diseases associated with anergy. Whilst the exact pathogenesis of myasthenia gravis is unknown, the available data support the concept of an immune deficiency disorder.

Detection of anti-acetylcholine receptor factors in serum and thymus from patients with myasthenia gravis

Since the blood and thymus of patients with myasthenia gravis may contain inhibitors of neuromuscular transmission that affect acetylcholine receptors of striated muscle, we used denervated rat muscle to test for inhibitors in 43 serums and 18 thymus glands from such patients. Seven per cent of serums inhibited the binding of 125l alpha-bungarotoxin to triton-solubilized receptors; 65 per cent interfered with binding of toxin-labeled receptors to concanavalin-A coupled to Sepharose gel, and 85 per cent formed IgG-receptor complexes detectable by immunoprecipitation. Serum inhibitory activity varied widely among patients with similar clinical manifestations and was not correlated with duration of myasthenia gravis or thymectomy. Among thymus extracts, 44 per cent were inhibitory in the concanavalin-A binding assay, whereas 72 per cent contained anti-receptor IgG. Thus, serums from patients with myasthenia gravis contain more than one anti-receptor factor.

Increased frequency of HL-A8 in Sjogren's syndrome

The histocompatibility antigen, HL-A8, was found to be elevated in patients with Sjogren's syndrome. Among 24 patients, the frequency of HL-A8 was 58% compared to 21% among controls (P less than 0.001 after correction). With the addition of this disorder to the list of other autoimmune diseases associated with HL-A8, it now seems possible to postulate a single basis autoimmune defect gene in high linkage disequilibrium with HL-A8.

Humoral antibodies to acetylcholine receptor in patients with myasthenia gravis

Sera from patients with myasthenia gravis (M.G.) were studied by the quantitative micro-scale complement-fixation assay for the presence of humoral antibodies against acetylcholine receptor (AChR). The purified receptor was extracted from the electrogenic tissue of the electric ray, Torpedo californica. A significant difference in the antibody titres was observed between myasthenic and non-myasthenic patients. Out of fifteen patients with myasthenia gravis, at least 12 (80%) had antibodies against AChR. Only one case out of twenty-four controls had an indication of anti-receptor antibodies. In view of observations on the role of AChR as the autoantigen in myasthenia gravis, such antibodies may have significance in producing the neuro-muscular block characteristic of the disease.

Myasthenia gravis associated with penicillamine treatment for rheumatoid arthritis

Four patients with rheumatoid arthritis (R.A.) developed myasthenia gravis after taking penicillamine. In one patient withdrawal of the drug was followed by spontaneous remission of the myasthenia, and in two the dose of anticholinesterase was subsequently reduced. In the fourth patient continuing penicillamine treatment was associated with increasingly severe myasthenic features, but on withdrawal of the drug these resolved. As myasthenia gravis rarely complicates R.A. its onset in these patients shortly after the start of penicillamine treatment suggested that penicillamine may have precipitated this condition.