Receptor Antibodies In Myasthenia Gravis Research Articles

Interventional Effect of Jianpi Bushen Granule Combined with Western Medicine on the Level of Serum Acetylcholine Receptor Antibodies in Myasthenia Gravis Patients

Objective: This study is aimed to investigate the clinical significance of regulating effect of Jianpi Bushen Granule (JBG) combined with Western medicine on the level of serum acetylcholine receptor antibodies (AchRAb) in myasthenia gravis (MG) patients, so as to offer a theoretical basis of the targeted therapy with AchRAb. Methods: We detected the level of anti-AchRAb with enzyme linked immunosorbent assay (ELISA) in the sera from 60 cases of MG patients (randomly divided into the trial group 30 cases, control group 30) for before and after treatment 6 months, and the clinical evaluation carried out by the Quantitative score of myasthenia gravis (QMG) for before and after treatment 3,6 months. Results: (1) Comparison of the level of serum AchRAb:All included MG patients, the positive rate of serum AchRAb was about 81.67% (49/60), and the trial group was 83.33% (25/30), the control group was 90% (27/30), and the serum AchRAb levels of the trial group (0.994 ± 0.417) was lower than that of the contral group (1.068 ± 0.358), but there was no significant difference between the two groups before treatment (P > 0.05). After 6 months of treatment, the serum AchRAb levels of the trial group (0.721 ± 0.280) was also significantly lower than that of the contral group (0.907 ± 0.387), and the serum AchRAb levels was decreased dramatically compared with the same group before treatment, there was significant difference between the two groups (P < 0.05). (2)Comparison of QMG scoring:QMG scoring was decreased dramatically in the trial group compared with that of the control group after treatment, there was significant difference (P < 0.05), moreover, the total effective rate in the trial group (50%,86.67%)was significantly higher than those in the control groups (23.33%, 40%) after 3,6 months treatment (P < 0.05). There was also significant difference in the clinical evaluation by the QMG between the two groups before and after treatment. (3) Adverse reactions: no obvious adverse reactions appeared among the two groups. Conclusions: JBG combined with Western medicine therapy on MG by regulating the level of patients’ serum AchRAb shows definite effects, and it is worthy of further studying. Abbreviations:< JBG: Jianpi Bushen Granule; AchRAb: acetylcholine receptor antibodiesin; MG: myasthenia gravis; ELISA: enzyme linked immunosorbent assay; QMG: Quantitative score of myasthenia gravis; AchR: acetylcholine receptor; N2AchRab: nicotinic acetylcholine receptor; TCM: Traditional Chinese Medicine; MuSK: muscle-specific kinase; NMJ: neuromuscular junction

G.P.11.06 Clinical correlations of binding and blocking acetylcholine receptor antibodies in myasthenia gravis

G.P.11.06 Clinical correlations of binding and blocking acetylcholine receptor antibodies in myasthenia gravis

Stiff, twitchy or wobbly—are GAD antibodies pathogenic?

Over the last decade or so there has been increasing recognition of the importance of measuring antibodies to neuronal proteins in the diagnosis and management of disease. Such antibodies can be classified into two main groups. First, there are those that are markers for a disease process, such as the paraneoplastic antibodies against Hu, Yo, Ma2, but which are not thought to cause the disease. This is because their targets are cytoplasmic or nuclear proteins that are not exposed on the surface of the neurons, and because the patients do not respond to immunotherapies such as plasma exchange, intravenous immunoglobulins or corticosteroids. Moreover, the antibodies do not necessarily associate with specific syndromes; for instance, Hu antibodies can be found in a wide range of disorders from neuronopathy to limbic encephalitis. By contrast, the second group includes those that are not only diagnostic biomarkers but are also pathogenic (or likely to be). These bind to important membrane proteins, their epitopes exposed on the outside of the target cells; they are usually syndrome specific, e.g. the acetylcholine receptor antibodies in myasthenia gravis and, most importantly, the patients do well with treatments that reduce the levels of the antibodies. Where do glutamic acid decarboxylase (GAD) antibodies, that are found in diabetes and stiff-person syndrome (SPS), fit into this scheme? GAD is a cytoplasmic enzyme …

Myasthenia gravis: presentation and outcome in 104 patients managed in a single institution

BACKGROUND AND OBJECTIVESFew studies have attempted to delineate the clinical profile of myasthenia gravis (MG) among people of Arab ancestry. Therefore, we sought to clarify the clinical profile, the outcome of treatment and the role of thymectomy in non-thymomatous MG in Saudi Arabia.PATIENTS AND METHODSWe retrospectively studied 104 patients followed over a mean period of 7.2 years (range, 1 to 22 years) at the King Khaled University Hospital, Riyadh, Saudi Arabia. Disease outcomes were compared among thymectomized and non-thymectomized patients according to the post-intervention status criteria of the Myasthenia Gravis Foundation of America (MGFA).RESULTSAge of onset was 22.5±9.3 years (mean±SD) in females and 28.2±15.9 years in males, with peaks in the second and third decades among females and the third and fourth decades among males. At diagnosis, a majority of patients had moderate generalized weakness, equivalent to MGFA class III severity. After medical treatment with or without thymectomy, 9.6% of all patients had achieved complete stable remission, 3.8% had pharmacological remission, 27.9% had minimal manifestations, 23.1% were improved, 20.2% were unchanged and 15.4% were worse. Only thymectomized patients without a thymoma achieved remission, a significant benefit over those who had no thymectomy (P=.02).CONCLUSIONMG presents at a younger age among Saudi Arabs compared to other racial groups. Thymectomy conferred significant benefits towards achievement of remission.

FC1.1 Correlating neuromuscular instability with acetylcholine receptor antibodies in myasthenia gravis

FC1.1 Correlating neuromuscular instability with acetylcholine receptor antibodies in myasthenia gravis

Acetylcholine receptor antibodies in myasthenia gravis are associated with greater risk of diabetes and thyroid disease

Myasthenia gravis (MG) may be associated with the presence of acetylcholine receptor antibodies (AChRAb) [seropositive MG (SPMG)] or their absence [seronegative MG (SNMG)]. Along with features of MG, the presence of the AChRAb may relate to the existence of other immune-mediated diseases. We sought to determine the association of SPMG with other potential autoimmune diseases. A retrospective evaluation of prospectively identified MG patients at a tertiary care center was performed, with patients separated into SPMG and SNMG. Prevalence of other immune-mediated disorders, as well as the epidemiology, sensitivity of diagnostic testing, and thymic pathology, was contrasted between both patient groups. Of the 109 MG patients identified, 66% were SPMG. SPMG was associated with a greater likelihood of significant repetitive stimulation decrement, the presence of either thymoma or thymic hyperplasia, and the presence of thyroid disease. In addition, all patients with a diagnosis of diabetes, concurrent with MG, were found to be SPMG. AChRAb and SPMG impart not only a distinctive clinical and electrophysiological phenotype of MG, but are also associated with the heightened presence of endocrinological disease.

Titin and ryanodine receptor antibodies in myasthenia gravis

Some myasthenia gravis (MG) patients have antibodies against skeletal muscle antigens in addition to the acetylcholine receptor (AChR). Two major antigens for non-AchR antibodies in MG are the Ca(2+) release channel of the sarcoplasmic reticulum, the ryanodine receptor (RyR) and titin, a gigantic filamentous muscle protein essential for muscle structure, function and development. RyR and titin antibodies are found mainly in thymoma MG patients and in a few late-onset MG patients and correlate with a severe MG disease. The presence of titin antibodies, which bind to key regions near the A/I junction and in the central I-band, correlates with myopathy. The immunosuppressant (FK506), which enhances Ca(2+) release from the RyR, seems to have a symptomatic effect on MG patients with RyR antibodies. The RyR antibodies recognize a region near the N-terminus important for channel regulation and inhibit Ca(2+) release in vitro. However, evidence that antibodies against the intracellular antigens RyR and titin are pathogenic in vivo is still missing.

Ryanodine receptor antibodies in myasthenia gravis: epitope mapping and effect on calcium release in vitro.

Patients with myasthenia gravis can have antibodies against skeletal muscle ryanodine receptor (Ry1), the sarcoplasmic reticulum calcium-release channel, which plays a crucial role in excitation-contraction coupling. We have screened a panel of overlapping Ry1 fusion proteins with Ry1 antibody-containing myasthenia gravis sera to identify the main immunogenic region. The pc2 Ry1 fusion protein representing a Ry1 region close to the N-terminus (residues 799-1172) was identified as the main immunogenic region for the antibodies. The binding kinetics of the Ry1 antibodies to the pc2 Ry1 fusion protein were tested using an optical biosensor. Ry1 antibodies in the IgG fraction from sera of patients with myasthenia gravis bound with high affinity and with a stoichiometry of 1:1. The functional effect of these Ry1 antibodies was tested in an in vitro Ca2+-release assay. The Ry1 antibodies induced a twofold increase of the half-maximal concentration for 4-Cl-m-cresol-induced Ca2+ release from terminal cisternae vesicles but had no effect on V(max). The effect on 4-Cl-m-cresol-induced Ca2+ release was specific, as preincubation of the active IgG fraction with the pc2 Ry1 fusion protein abolished the inhibition. These data suggest that the Ry1 sequence defined by residues 799-1172 is involved in the regulation of Ry1 function, and that this regulation could be functionally affected in vivo in patients with myasthenia gravis.

β 2-Adrenergic receptor antibodies in myasthenia gravis

Although autoantibodies against the nicotinic acetylcholine receptor are the characteristic feature of the autoimmune disease myasthenia gravis (MG), no strong correlation is found between the autoantibody titer and the degree of clinical severity. Numerous studies have attempted to detect the presence of other autoantibody populations that might have a role in the pathology of the disease. We report, for the first time, that 18% of the MG patients we screened have antibodies in their serum to a peptide corresponding to the second extracellular loop of the human β 2-adrenergic receptor (residues 172–197). Affinity purified antibodies to the β 2-adrenergic receptor peptide 172–197 reacted with the human β 2-adrenergic receptor protein obtained from transfected E. coli cell membrane extracts, but did not cross-react with the human AChR. Sufficient material was obtained from nine MG patients and it was found that the gamma globulin fraction from these patients immunoprecipitated the receptor, and that affinity purified IgG to peptide 172–197 competed for receptor binding with the β-antagonist iodo-cyanopindolol. Using truncated peptides or amino acid modification procedures, no immunodominant B-cell epitope could be detected within region 172–197. Thus, a subpopulation of MG patients possesses anti-β 2-adrenergic receptor antibodies which are a distinct set of autoantibodies with possible pharmacological activity.

Immunological specificity and cross-reactivity of anti-acetylcholine receptor and anti-presynaptic membrane receptor antibodies in myasthenia gravis

Antibodies against acetylcholine receptor (AChR), a protein that binds to α-bungarotoxin (α-BuTx), are characteristic for myasthenia gravis (MG) and are considered to be of importance in the pathogenesis of the disease. Antibodies against a β-BuTx binding protein, presynaptic membrane receptor (PsmR), have also been reported in most MG patients. We have analysed the specificity and cross-reactivity of antibodies to bovine AChR and PsmR in sera from 11 patients with MG. More than 90% of antibodies to PsmR were adsorbed specifically by PsmR conjugated affinity chromatography. Similarly, more than 90% of anti-AChR antibodies were absorbed by AChR conjugated affinity chromatography. Specificities of antibodies from affinity chromatography were also confirmed by ELISA and agarose isoelectric focusing. However, the antibodies to PsmR and AChR from MG patients' sera showed about 45–55% cross-reactivity, and there was a high correlation between serum levels of both antibodies. The demonstration of anti-PsmR antibodies could be important in documenting presynaptic damage and understanding the pathogenetic process in MG.

Therapeutic immunoadsorption of acetylcholine receptor antibodies in myasthenia gravis.

Therapeutic immunoadsorption of acetylcholine receptor antibodies in myasthenia gravis.

Acetylcholine receptor antibodies in myasthenia gravis: use of a qualitative assay for diagnostic purposes.

We have modified the techniques of Lindstrom and of Tindall to measure serum acetylcholine receptor antibody using human antigen bound to 125I-alpha Bungarotoxin. By using 10 microliters of serum and precipitating antigen-antibody complexes with an excess of staph A, we found that only one out of 43 patients with clinically diagnosed active generalized Myasthenia Gravis had no antibodies. In pooling these results with the results of tests done for diagnostic purposes we found positive results in 54/55 generalized active MG, 8/21 MG in remission, 16/37 ocular MG and 0/55 healthy controls. Two out of 38 non MG were also positive and their clinical diagnosis of botulism and penicillamine treated rheumatoid arthritis have been confirmed by a one year follow-up. Most of these sera were also tested for reactivity with fetal calf AchR. Six out of 49 samples positive with the human receptor were negative with calf receptor. We conclude that our technique is extremely useful for the diagnosis of Myasthenia Gravis and that fetal calf antigen cannot replace human antigen in the assay.

Antimuscle and antiacetylcholine receptor antibodies in myasthenia gravis

The sera of 134 patients were examined for antimuscle antibodies by immunofluorescence (IF). These derived from 77 myasthenics, 30 myasthenics with thymoma, 6 patients with thymoma and no clinical evidence of myasthenia, and 21 patients with other autoimmune or neuromuscular diseases. Three separate patterns of antimuscle antibodies could be identified in the myasthenic sera by examination of the relaxed glycerinated myofibrils by both IF and phase-contrast optics: A-band (9 with thymoma, 1 without), I-band (11 with thymoma, 17 without), and a mixed A plus I pattern (5 with thymoma, 3 without). Seventy-seven myasthenic serum samples (24 with thymoma, 53 without) were available for evaluation of antibodies to acetylcholine receptor (anti-AChR) by radioimmunoassay. Ninety-one percent reacted with crude human receptor extract and 80% with receptor extracted from denervated rat muscle. There was no correlation between the titers of anti-AChR and the presence or staining patterns of antimuscle antibodies, but patients without anti-AChR did not have antimuscle antibodies. Myasthenics with thymoma had the highest prevalence of anti-AChR (23/24) and of antimuscle antibodies (25/30), and 15 of the 20 positives stained A-bands alone or with I-band, as compared to 4 of 21 positive reactions in those without tumor. Immunoabsorption, which removed or significantly reduced anti-AChR, did not alter antimuscle reactivity. The discrepancies between anti-AChR levels and the presence and types of antimuscle antibodies suggest that these are independent autoantibodies. Current theories of immunopathogenesis implicate altered thymic antigens or a major breakdown in immune regulation, either of which could explain their production.

Anti-acetylcholine receptor antibodies in myasthenia gravis: Part 3. The effect of thymectomy

The clinical condition and the serum levels of antibodies to acetylcholine receptor protein were followed in 30 patients with myasthenia gravis before and in a period varying from 2 to 4 (mean 3) yr after thymectomy. Twenty-five patients improved in the 2 yr following thymectomy. A highly significant correlation was found between the change in clinical condition and the change in antibody levels. Only 3 patients improved without a fall of antibody level. Prethymectomy antibody levels were positively correlated with the severity of the clinical condition and with the degree of thymus hypertrophy.

Displacement of 125I-α-bungarotoxin from 125I-α-bungarotoxin-labelled acetylcholine receptor complexes by anti-acetylcholine receptor antibodies in myasthenia gravis

Displacement of 125I-α-bungarotoxin from 125I-α-bungarotoxin-labelled acetylcholine receptor complexes by anti-acetylcholine receptor antibodies in myasthenia gravis

人工レセプターとその血液浄化治療への応用

Newly developed artificial receptors and their clinical application are briefly described from the standpoint of biomimetic organic chemistry. Artificial receptors dealt with here are those for immune complexes in immune complex diseases, for anti-acetylcholine receptor antibodies in myasthenia gravis, and for low density lipoprotein in familial hypercholesterolemia, and are classified by intermolecular interaction forces, which are hydrophobic and electrostatic.

A practical enzyme immunoassay for anti-acetylcholine receptor antibodies in Myasthenia Gravis

A practical enzyme immunoassay (EIA) has been developed for the measurement of anti-acetylcholine receptor (AChR) antibodies in sera from patients with myasthenia gravis (MG). This system is based on the double antibody technique, using denervated rat muscle AChR labeled with horseradish peroxidase-linked α-bungarotoxin (HRP-αBGT). This method has the following advantages compared to conventional radioimmunoassay (RIA): (1) HRP-αBGT is more stable than [ 125I]αBGT and can be used for at least one year without any loss of the binding activity to AChR and enzymatic activity, (2) the procedure avoids the use of radioactive isotopes, and (3) the equipment for our EIA is more economical than that for RIA.

Analysis of false negative results in the immunoassay for anti-acetylcholine receptor antibodies in myasthenia gravis

Possible causes for the failure of immunoassays to detect anti-acetylcholine receptor activity in serum from confirmed myasthenia gravis (MG) patients were investigated. A more sensitive assay, using Protein A to trap immune complexes (ARIA), was applied to 65 MG sera which were negative in the usual assay and to 42 normal human sera. Normal and negative MG sera had antibody (Ab) activity in the same range (50–70 p M). Titers present in 70% of normal sera appeared to the specific antireceptor antibodies as defined by tests for antigen specificity. Thus, higher sensitivity assays did not improve discrimination of MG from normals. In a second group of 108 MG sera studied, 48 were negative by the usual assay criteria in a rat acetylcholine receptor immunoassay. Further detailed analysis of this negative group showed that 3 48 had IgG 3 antibody not detectable in the test, 14 48 had Ab's recognizing human receptor determinants exclusively, 29 48 had toxin blocking Ab's not determined by immunoassays, and 6 48 were negative in all tests. The results indicate that the exclusive occurrence of toxin-blocking antibodies in MG subjects is a major factor contributing to false negatives in the ARIA test. Estimates of the amount of Ab's with this functionality indicated that they are present in very much smaller amounts than other classes of anti-receptor Ab's. Degree of blocking activity in patient serum showed a fair correlation with severity of disease. Thus, blocking antibodies appear capable of causing all degrees of disease severity in the absence of other types of antireceptor Ab's. The development of a sensitive and quantitative in vitro assay for blocking antibodies combined with the usual immunoassay would be a major improvement for a MG diagnostic test, with >94% positivity predicted.

Anti-acetylcholine receptor antibodies in myasthenia gravis: Part 2. Clinical and serological follow-up of individual patients

Circulating antibodies to acetylcholine receptor protein (anti-AChR) were measured in the sera collected from 75 patients (53 women, 22 men, ages 9–83 year, 20 with a thymoma) with myasthenia gravis (MG) during 5–44 (mean 25) months. The clinical state of each patient was graded on a 6-point scale. Anti-AChR concentrations were measured by a radioimmunoassay with human antigen. We analysed the relation between the change in clinical state and the change in anti-AChR concentration in 155 periods (1–7, mean 2.1 per patient). The change in clinical state is given as the difference in score at the onset and at the end of this period. The change in anti-AChR concentration is expressed as the percentage of the original concentration at the onset of the period. The results were analysed in relation to the therapy and to the severity of the MG at the onset of each period. A strong correlation between a change in anti-AChR concentration and a change in clinical condition existed during treatment with prednisone or immunosuppression and in the period after thymectomy, while a weaker correlation was present in periods without immunosuppression. In only 3 patients did the changes in anti-AChR concentration preceed the clinical change. No changes in anti-AChR concentrations were found if improvement was due to the effect of anticholinesterases or if deterioration was caused by infection or emotion. The serial measurement of anti-AChR may be a valuable method of following the basic trend of the MG in severely affected patients.

Immune regulation in myasthenia gravis: evidence for an increased suppressor T-cell population.

The production of anti-acetylcholine receptor antibodies in myasthenia gravis represents a persistent and unexplained break in self-tolerance. The studies reported here demonstrate an altered regulatory T-cell population with an increase in the percentage of circulating T-suppressor cells as defined by two independently developed murine monoclonal antibody markers. Leu 2a- and OKT8a-positive cells were significantly increased within the T-cell population in myasthenia gravis (25.0 +/- 6.4% versus 20.7 +/- 2.9% and 34.9 +/- 7.0% versus 26.0 +/- 3.2%, respectively) compared to an age- and sex-equivalent group. In addition, the circulating total T-cell population was reduced in myasthenia gravis. Patients with symptomatically uncontrolled disease (with or without immunosuppression) demonstrated significantly altered ratios of helper to suppressor T-cells, while patients whose myasthenia symptoms were controlled did not differ from normal subjects.