Because of the antibody-mediated pathogenesis of MG, it is of particular interest to understand the effects of oral administration of the autoantigen AChR on the disease process. It is now clear that feeding AChR prior to immunization can prevent clinical manifestation of EAMG. It initially primed, then inhibited, antibody responses to foreign (Torpedo) AChR and self (rat) AChR, with a delayed onset. Cellular responses to AChR, evaluated by lymphocyte proliferation and IL-2 production, were markedly inhibited. The effects were dependent on the dose and purity of the fed antigen. Tolerance to an orally administered unrelated antigen, OVA, was more prompt in development and more profound, illustrating the influence of the nature of the antigen on tolerance. The tolerance induced was antigen specific. Oral administration of AChR after immunization resulted in inhibition of the clinical manifestation of EAMG, concomitant with a paradoxical enhancement of the AChR-antibody responses. Both the clinical benefit and the antibody response appear to be dependent on the feeding protocol. These findings suggest that a molecule with less immunogenic potential than native AChR may be required for safe and effective oral treatment of ongoing disease.

Annals of the New York Academy of SciencesVolume 681, Issue 1 p. 298-302 A Novel Therapy for Myasthenia Gravis by Reducing the Endocytosis of Acetylcholine Receptorsa RALPH W. KUNCL, RALPH W. KUNCL Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorILAN WITTSTEIN, ILAN WITTSTEIN Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorROBERT N. ADAMS, ROBERT N. ADAMS Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorWINSTON W. WIGGINS, WINSTON W. WIGGINS Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorORLANDO AVILA, ORLANDO AVILA Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorALAN PESTRONK, ALAN PESTRONK Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorKEVIN McINTOSH, KEVIN McINTOSH Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorDONNA LUCAS, DONNA LUCAS Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorSHARI DESILVA, SHARI DESILVA Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorMOHAMED LEHAR, MOHAMED LEHAR Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorDANIEL B. DRACHMAN, DANIEL B. DRACHMAN Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this author RALPH W. KUNCL, RALPH W. KUNCL Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorILAN WITTSTEIN, ILAN WITTSTEIN Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorROBERT N. ADAMS, ROBERT N. ADAMS Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorWINSTON W. WIGGINS, WINSTON W. WIGGINS Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorORLANDO AVILA, ORLANDO AVILA Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorALAN PESTRONK, ALAN PESTRONK Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorKEVIN McINTOSH, KEVIN McINTOSH Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorDONNA LUCAS, DONNA LUCAS Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorSHARI DESILVA, SHARI DESILVA Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorMOHAMED LEHAR, MOHAMED LEHAR Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this authorDANIEL B. DRACHMAN, DANIEL B. DRACHMAN Department of Neurology, The Johns Hopkins University School of Medicine, Meyer 5-119, 600 North Wolfe Street, Baltimore, Maryland 21205Search for more papers by this author First published: June 1993 https://doi.org/10.1111/j.1749-6632.1993.tb22900.xCitations: 4 a This work was supported by Grants from the Muscular Dystrophy Association, the National Institute of Neurological Diseases and Stroke (NS26455, NS23719), and by gifts from the Jay Slotkin Fund for Neuromuscular Research. R. W. Kuncl was the recipient of a Teacher Investigator Development Award (NINDS NS00734), an Andrew W. Mellon Foundation Clinician Scientist Career Development Award, and the Capitol Award for Scientific Achievement of the Myasthenia Gravis Foundation of Greater Washington, in partial support of this research. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume681, Issue1Myasthenia Gravis and Related Disorders: Experimental and Clinical AspectsJune 1993Pages 298-302 RelatedInformation

We studied the incidence and clinical correlates of serum antibodies to GM1 and GD1a gangliosides in patients with classical amyotrophic lateral sclerosis (ALS) and other “motor nerve” syndromes. Serum antibodies to GM1 and GD1a gangliosides were measured using enzyme‐linked immunosorbent assays. Our results showed that polyclonal immunoglobulin M (IgM) antibodies to the GM1 or GD1a ganglioside or both were present at serum dilutions of 1:25 to 1:4,000 in 78% (57/73) of patients with ALS. Only 8% of normal controls had similar antibodies. The pattern of serum antibody reactivity correlated with the pattern of clinical involvement in our patients. Selective reactivity to GDla ganglioside was common when upper motor neuron signs were prominent. IgM reactivity to GM1 ganglioside was common in ALS patients with prominent lower motor neuron signs. Most patients with motor neuropathies had serum reactivity to both GM1 and GDla gangliosides. These results provide further evidence of ongoing autoimmune processes in ALS patients. There is a strong relationship between serum antiganglioside antibodies and patterns of clinical involvement in ALS.

We compared the effects of treatment of patients with prednisone or cyclophosphamide on a series of different types of autoantibodies. Levels of antiacetylcholine receptor (anti-AChR) antibodies and of antibodies to GM, and GD,, gangliosides were measured in patients with a variety of neuromuscular disorders before and after treatment. Most patients had several autoantibodies present. We showed that prednisone treatment resulted in a reduction in titers of anti-AChR but not angantiglioside antibodies. Cyclophosphamide treatment produced a reduction of antiganglioside antibody titers. An intravenous and oral regimen was more effective than a single intravenous course of cyclophosphamide. We conclude that an immunosuppressive medication such as prednisone may reduce levels of some autoantibodies while producing no change in others, even in an individual patient. In addition, cyclophosphamide can suppress autoantibodies that prednisone does not. These differences in immunopharmacologic responses suggest that there are several distinct mechanisms of autoantibody production in humans. The utility of immunosuppressive medications in specific disease processes may be related in part to the mechanism of production of pathogenic antibodies.

We report the presence of serum antibodies directed against GM1 ganglioside, a defined neural antigen, in many patients with amyotrophic lateral sclerosis (ALS). We examined serum from a series of patients with well-documented clinical diagnoses. Serum antibodies to GM1 ganglioside were measured using ELIS A assays. Our results showed that polyclonal IgM anti-GM1 antibodies were present at dilutions of 1:25 to 1:2,000 in 42 of 74 (57%) patients with ALS. The anti-GM1 antibodies were especially frequent in patients with prominent lower motor neuron signs (41/59; 69%). Few normal controls (2/23) and motor-sensory neuropathy patients (3/27) had similar antibodies. Anti-GM1 antibodies did occur in patients with nonneural autoimmune disorders. However, the anti-GM1 antibodies in these patients tended to differ from those in ALS based on an analysis of their light chain types. Further examination of the role and spectrum of serum antiganglioside antibody activity in motor neuron syndromes is warranted.

We report 2 patients with a treatable, immune‐mediated motor polyneuropathy associated with antibodies to defined neural antigens. In these patients asymmetrical weakness developed in one arm and progressed over 2 to 3 years to involve the other arm, legs, and trunk. Both patients were initially diagnosed as having lower motor neuron forms of amyotrophic lateral sclerosis. However, repeated electrophysiological testing eventually showed multifocal conduction blocks in motor but not sensory fibers compatible with patchy selective demyelination. Serum testing by thin‐layer chromatography and enzyme‐linked immunosorbent assay revealed that both patients had high titers of antibody directed against GM1 and other gangliosides. Initial therapeutic trials of prednisone (100 mg daily for 4 to 6 months) and plasmapheresis were unsuccessful. Treatment with cyclophosphamide, however, was followed by Marchked improvement in strength in both patients.

A therapeutic strategy was designed to eliminate the humoral immune response to acetylcholine receptor (AChR) in ongoing experimental autoimmune myasthenia gravis (EAMG). Rats with EAMG were treated with a protocol consisting of three components: (1) A single high dose of cyclophosphamide (200 mg/kg) was used to produce a rapid and sustained fall in the anti-AChR antibody levels by preferential destruction of antibody-producing B-lymphocytes. "Memory" lymphocytes were not eliminated by cyclophosphamide. (2) Irradiation (600 rads) was used to eliminate the "memory" cells. It eliminated the anamnestic response to a challenge with the antigen AChR. (3) Bone marrow transplantation was used to repopulate the hematopoietic system after the otherwise lethal dose of cyclophosphamide. We used bone marrow from syngeneic rats with active EAMG to simulate an autologous transplant. Rats with EAMG treated with this combined protocol showed a prompt and sustained fall in the anti-AChR antibody levels and had no anamnestic response to a challenge with AChR. Thus, an affected animal's own marrow could be stored and used later for repopulation after cyclophosphamide-irradiation treatment. This treatment eliminates the animal's ongoing immune responses and reconstitutes the immune system in its original state. The success of this approach suggests that, if their safety could be established, similar "curative" strategies might be developed for the treatment of patients with severe antibody-mediated autoimmune disorders, such as myasthenia gravis.

We have treated animals with an ongoing autoimmune disease, experimental autoimmune myasthenia gravis (EAMG), using a strategy designed to eliminate the antibody-producing cells. During well-established EAMG, a single high dose of cyclophosphamide was given because of its known effectiveness against B-lymphocytes. To counteract the lethal effects of the drug, the rats were "rescued" by bone marrow cell transplantation. This treatment produced a rapid and sustained fall of antibody titers against both the immunizing antigen (Torpedo acetylcholine receptor) and the autoantigen (rat acetylcholine receptor). Immunologic memory, as measured by an anamnestic response to the antigen, was partially suppressed. Cyclophosphamide treatment produced improvement in the neuromuscular defect: treated animals had, on the average, twice as many acetylcholine receptors at neuromuscular junctions compared with untreated EAMG animals. This treatment method of short-term high doses of an immunosuppressive drug, such as cyclophosphamide, may eventually prove useful for human myasthenia gravis and other autoimmune diseases.

The pathogenesis of myasthenia gravis involves a humorally mediated autoimmune attack directed against acetylcholine receptors of skeletal muscles. Antibodies against acetylcholine receptors are detected in the serum of more than 80 per cent of patients, but the antibody titers correspond poorly with the severity of disease. To distinguish between antibody titers and antibody activity, we measured the ability of serum immunoglobulin from 49 patients to induce accelerated degradation or blockade of the binding sites of acetylcholine receptors, using a mammalian skeletal-muscle tissue-culture system. Immunoglobulin from 41 of 45 patients tested (91 per cent) increased the rate of degradation of acetylcholine receptors, and the relative increase in the degradation rate corresponded closely (P less than 0.001) with clinical status. Immunoglobulin from 42 of 48 patients tested (88 per cent) produced blockade of receptors, and the extent of the blockade also corresponded with clinical status (P less than 0.001). An index of the combined activities of the immunoglobulin in accelerating degradation and producing blockade of acetylcholine receptors was elevated in 43 of 44 patients (98 per cent) whose immunoglobulins were tested for both activities; this index predicted the patients' clinical status significantly better (P less than 0.001) than either measure alone. This finding suggests that the functional ability of antibodies to decrease the number of available acetylcholine receptors by these two mechanisms is clinically relevant in the pathogenesis of myasthenia gravis.

Annals of the New York Academy of SciencesVolume 377, Issue 1 p. 175-188 ANTIBODY-MEDIATED MECHANISMS OF ACh RECEPTOR LOSS IN MYASTHENIA GRAVIS: CLINICAL RELEVACE* Daniel B. Drachman, Daniel B. Drachman Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this authorRobert N. Adams, Robert N. Adams Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this authorLorraine F. Josifek, Lorraine F. Josifek Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this authorAlan Pestronk, Alan Pestronk Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this authorElis F. Stanley, Elis F. Stanley Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this author Daniel B. Drachman, Daniel B. Drachman Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this authorRobert N. Adams, Robert N. Adams Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this authorLorraine F. Josifek, Lorraine F. Josifek Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this authorAlan Pestronk, Alan Pestronk Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this authorElis F. Stanley, Elis F. Stanley Department of Neurology Johns Hopkins University School of Medicine Baltimore, Maryland 21205Search for more papers by this author First published: December 1981 https://doi.org/10.1111/j.1749-6632.1981.tb33731.xCitations: 25 * This work was supported by NIH Grants Nos. 5 RO1 ND04817 and 5 PO1 NS10920. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume377, Issue1Myasthenia Gravis: Pathophysiology and ManagementDecember 1981Pages 175-188 RelatedInformation

The fundamental abnormality affecting the neuromuscular junctions of myasthenic patients is a reduction of available AChRs, due to an autoimmune attack directed against the receptors. Antibodies to AChR are present in most patients, and there is evidence that they have a predominant pathogenic role in the disease, aided by complement. The mechanism of antibody action involves acceleration of the rate of degradation of AChRs, attributable to cross-linking of the receptors. In addition, antibodies may block AChRs, and may participate in producing destructive changes, perhaps in conjunction with complement. The possibility that cell-mediated mechanisms may play a role in the autoimmune responses of some myasthenic patients remains to be explored. Although the target of the autoimmune attack in myasthenic patients is probably always the acetylcholine receptors, it is not yet clear which of these immune mechanisms are most important. It is likely that the relative role of each mechanism varies from patient to patient. One of the goals of future research will be to identify the relative importance of each of these mechanisms in the individual patient, and to tailor specific immunotherapeutic measures to the abnormalities found.

Antibodies in the sera of patients with myasthenia gravis are believed to play an important role in the pathogenesis of the disorder. They have recently been shown to accelerate the degradation of acetylcholine receptors in cultured mammalian skeletal muscle and at intact neuromuscular junctions. To elucidate the mechanism of the antibody-accelerated degradation process, we have prepared cultures in which one set of acetylcholine receptors was exposed to myasthenic immunoglobulin while a second set of acetylcholine receptors, newly incorporated after exposure to the immunoglobulins, was not. The set of acetylcholine receptors with bound myasthenic immunoglobulin was degraded at 2 to 3 times the normal rate, while the second set of acetylcholine receptors without bound immunoglobulin was degraded at the control rate. This suggest that the binding of antibody from myasthenic patients alters the acetylcholine receptors in some way that causes them to be selected for preferential degradation by the muscle cells. New synthesis and incorporation of the acetyl-choline receptors into the surface membrane of cultured skeletal muscle was unaffected by exposure to myasthenic immunoglobulin.

The decrease of acetylcholine receptors at neuromuscular junctions of myasthenic patients has been attributed to an antibody-mediated autoimmune process that accelerates receptor degradation. We studied the mechanism of this process in skeletal-muscle cultures, using intact antibodies and antibody fragments. Addition of myasthenic IgG or its divalent fragment, F(ab')2, to cultures accelerated the rate of acetylcholine-receptor degradation threefold. By contrast, the monovalent fragment, Fab, from myasthenic serum had no effect on degradation, although it bound to acetylcholine receptors. Addition of a second, "piggyback" antibody to cross-link the Fab:receptor complexes resulted in a threefold increase of the degradation rate. Similarly, when acetylcholine receptors with bound alpha-bungarotoxin were cross-linked by the addition of specific antibody against alpha-bungarotoxin, the degradation rate increased approximately threefold. The effect of myasthenic patients' antibodies in accelerating degradation of acetylcholine receptors is attributed to their ability to cross-link the receptors.