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The association between myasthenia gravis (MG) and polymorphic amino acid domains in the HLA-DQ molecule was studied in 79 Swedish patients and 155 unrelated, population-based controls. A domain unique for DQB1 ∗ 0201 was positively associated in MG patients with thymic hyperplasia or an early disease onset, and two domains with residues common to DQA1 ∗ 01 alleles or DQB1 ∗ 05 and DQB1 ∗ 06 alleles were negatively associated in patients with thymic hyperplasia or an early disease onset. Our results suggest that MG associated with thymic hyperplasia and thymoma differ in their HLA-DQ association and thus are likely to have different pathogenic mechanisms.

Multiple myeloma is characterized by a proliferation of clonal B lymphocytes and plasma cells. The idiotypic structure of clonal immunoglobulin (Ig) expressed on the tumour B-cell surface can be regarded as a tumour-specific antigen and, as such, a potential target for anti-idiotypic T and B-cells in an immune regulation of the tumour-cell clone. Active immunization using the autologous mono-clonal Ig as a 'vaccine' was shown to induce tumour-specific immunity in murine B-cell tumours and in human B-cell lymphoma. With the aim to induce or amplify an anti-idiotypic response in multiple myeloma, five stage I-III patients were repeatedly immunized with the autologous monoclonal IgG. Induction of idiotype-specific cellular immunity was analysed in vitro by an enzyme-linked immunospot assay (interferon-gamma and interleukin-4 secreting cells). B cells secreting anti-idiotypic IgM antibodies were also analysed. An anti-idiotypic T-cell response was amplified 1.9-5-fold in three of the five patients during immunization. The number of B cells secreting anti-idiotypic antibodies also increased in these three patients. In two of the patients induction of idiotype-specific immunity was associated with a gradual decrease of blood CD19+ B cells. The induced T-cell response was eliminated during repeated immunization. Further studies are warranted to optimize the immunization schedule in order to achieve a long-lasting T-cell immunity against idiotypic determinants on the tumour clone. A role for immunity in controlling the tumour clone remains to be established.

SUMMARY Eighteen percent of patients with myasthenia gravis (MG) have serum antibodies against a synthetic peptide corresponding to the second extracellular loop of the human β2AR (residues 172–197). In this study we examined T and B cell responses to the peptide, using assays to detect individual cells secreting interferon-gamma (IFN-γ) and IL-4 or antibodies against the peptide, and by measuring thymidine incorporation in response to the peptide. The peptide from the β2AR induced cytokine secretion from blood mononuclear cells in 67% of MG patients, compared with 14–28% of the control groups. Cells secreting antibodies binding to the peptide were present in 54% of MG patients and in 19–28% of controls. The numbers of β2AR-reactive cells were higher in MG patients than in controls. Peptide-induced increase in thymidine incorporation in cells was also more frequently demonstrated in patients (26%) compared with controls (about 10%). Activation of cells was dependent on monocytes and on MHC class II DR antigen. Based on the pattern of the cytokine secretion induced, β2AR-reactive T cells comprise both T helper type-1 and type-2 subsets. In addition, control peptide-reactive T and B cells were much less frequently demonstrated in the patients, and the number of such cells did not differ between the groups. Our results show that β2AR-reactive cells are present in most patients with MG. Such autoreactive antibodies and cells might play a role in the pathogenesis of the disease by influencing the function of skeletal muscle and immune systems.

Abstract Oxidative modification of LDL has been proposed as an early and crucial step in the development of atherosclerosis, and antibodies against such modified LDL are found in both healthy individuals and patients with atherosclerosis. In this study, 62 patients who were surgically treated for peripheral arterial occlusive disease below the age of 50 were investigated and compared with age- and sex-matched healthy individuals in a case-control study. Autoantibodies against oxidized LDL were measured with an enzyme-linked immunosorbent assay method. Risk factors such as smoking, hypertension, family history of premature cardiovascular events, and lipoprotein levels were also determined. The patients had significantly higher levels of autoantibodies against oxidized LDL; significantly higher levels of total cholesterol, LDL cholesterol, triglycerides, and apo A-I; and significantly lower levels of HDL cholesterol than did control subjects. In multivariate analyses autoantibodies against oxidized LDL discriminated better between patients and control subjects than did any of the different lipoprotein analyses. Among patients, the presence of hypertension and a family history of cardiovascular events were the only factors significantly associated with increased levels of autoantibodies against oxidized LDL.

Neonatal autoimmune diseases are thought to be due to the transfer of maternal autoantibodies. However, there is a puzzling lack of correlation between maternal autoantibody titres and disease in the neonate. So far, no factor reliably predictive of neonatal disease has been found. Agalactosyl IgG is a variable feature of normal IgG. Preliminary studies indicated that the percentage of agalactosyl IgG is lower in the serum of normal neonates, than in the serum of the mother at delivery. Since raised % agalactosyl IgG is often associated with autoimmune disease we sought to determine whether this relationship holds true in a neonatal autoimmune disease. We measured the % agalactosyl IgG in paired maternal-cord sera from patients with myasthenia gravis, some of whom had offspring with neonatal myasthenia gravis. We found that the percentage of agalactosyl IgG was significantly higher in affected than in unaffected neonates. Moreover % agalactosyl IgG was higher in sera of affected neonates than in serum from their mothers, while unaffected infants of mothers with myasthenia had %Gal(0) lower than their mothers, mimicking the normal situation. This suggests that in affected neonates a high proportion of the IgG is synthesised by the baby itself rather than derived from the mother. This agrees with previous evidence based on the presence of idiotypes not found in the mother which implied that the neonates with neonatal myasthenia gravis produce their own autoantibodies.

We treated a patient with severe myasthenia gravis with a chimeric (murine/human) anti-CD4 monoclonal antibody (cM-T412) for 7 days and followed the therapeutic effect by standardized muscle function tests, single-fiber electromyography, and immunologic examinations of disease-specific B- and T-cell functions. Clinical and electrophysiologic improvement began within 4 days, lasted for 3 months, and was maximal between days 16 and 58. The CD4+ lymphocytes decreased to a minimum of 80 cells per microliters of peripheral blood, recovered slowly during the first year of follow-up, and did not correlate with changes in disease severity. T-cell stimulation by human acetylcholine receptor was abolished by the treatment but became detectable at the time of worsening of symptoms. The concentration of acetylcholine receptor antibodies in serum was not decreased by the treatment. The results suggest that anti-CD4 antibody administration could be effective in the treatment of severe myasthenia gravis and indicate that acetylcholine receptor-specific T lymphocytes might contribute to the disturbed neuromuscular transmission in the disease.

Patients with myasthenia gravis have a high prevalence of acetylcholine receptor-specific T lymphocytes in the peripheral blood. Our earlier study shows that these T lymphocytes are stimulated to secrete interferon (IFN)-gamma and interleukin (IL)-2 in response to the autoantigen. Such stimulated T cells may be subdivided into different subsets according to the pattern of cytokine production. In the present study we have investigated the subpopulations of cells by analyzing their IL-4, IFN-gamma and IL-2 secretion pattern. Autoantigen-stimulated IL-4 secretion was found in 55% of the patients, IFN-gamma secretion in 86% and IL-2 secretion in 72%. T lymphocytes from all patients who responded with increased IL-2 secretion also showed increased IFN-gamma secretion. Stimulated IL-4 secretion was detected both in the presence and absence of stimulated IFN-gamma secretion. Depletion of monocytes/macrophages from peripheral blood mononuclear cell preparation and treatment of the cells with a mouse anti-human HLA-DR antibody abolished the secretion of IFN-gamma and IL-4. There were positive correlations between the numbers of IFN-gamma- and IL-2-secreting T cells and the numbers of B cells secreting antibodies against the acetylcholine receptor. Our results show that acetylcholine receptor-stimulated T lymphocytes secrete IL-4, IFN-gamma and/or IL-2. This T cell response is major histocompatibility complex (MHC) class II-restricted and monocyte/macrophage-dependent. Our study indicates that both Th1/Th2 or Th0 subpopulations of the T lymphocytes are involved in the autoimmune response in myasthenia gravis.

In animals fed a hypercholesterolemic diet, development of atherosclerosis is preceded by attachment of mononuclear leukocytes to the arterial endothelium. Early lesions begin to develop as monocytes migrate into the intima and ingest lipids. A major part of these lipids is believed to be derived from oxidatively modified low density lipoprotein (LDL). In the present study we demonstrate that human mononuclear leukocytes exposed to low concentrations of copper-oxidized LDL secrete one or several factors that stimulate the expression of intercellular adhesion molecule-1 (ICAM-1, CD54), vascular cell adhesion molecule (VCAM-1) and endothelial selectin (E-selectin-1, ELAM-1), whereas native LDL was found to be without effect. Exposure of endothelial cells to non-conditioned medium containing oxidized LDL did not influence the expression of adhesion molecules. Incubation of endothelial cells with conditioned medium from mononuclear cells grown in the presence of oxidized LDL also resulted in a three-fold increase in the binding of monocytoid U937 cells. The present findings suggest that mononuclear leukocytes exposed to oxidatively modified LDL in early atherosclerotic lesions may stimulate the recruitment of other leukocytes by secreting cytokines which induce the expression of adhesion molecules on the endothelium.

A 27-year-old woman with severe recurrent angioedema and urticaria since 5 years was found to have high levels of circulating immune complexes in the peripheral blood. These immune complexes contained antibodies against bovine serum albumin. Elimination of bovine products from the diet resulted in disappearance of immune complexes within 2 days and addition again to the diet led to reappearance within 24 h. The patient has now been in complete remission during 4.5 years under treatment with a diet free of bovine proteins but containing products from chicken, egg, pork and fish. The immune complexes have not reappeared. Thus, immune complexes containing antibodies against alimentary antigens can provoke acute vascular damage manifested as angioedema and urticaria. In such cases, elimination of the causative antigen from the diet can result in patient being cured.

In myasthenia gravis the production of anti-acetylcholine receptor antibodies is modulated by acetylcholine receptor-specific T cells. Most B- and T-cell epitopes are located on the alpha-subunit of the receptor. In order to map the fine specificity of the antigen-specific T cells in myasthenia gravis, T-cell stimulation in response to 70 hexapeptides was studied in 24 patients and 24 healthy individuals. The hexapeptides overlapped with one amino acid and represented residues 10-84 of the NH2-terminal part of the alpha-subunit of the receptor. The IFN-gamma secretion from single T cells was used to detect T-cell stimulation. A significant difference in the T-cell response to several of the peptides was found between patients and healthy controls. The majority of the hexapeptides induced T-cell stimulation in at least one of the patients. Peptide-induced T-cell stimulation was evident in all but one of the patients. The results indicate that different epitopes and multiple T-cell clones are involved in the T-cell recognition of the acetylcholine receptor.

CD5+ B cells might be involved in autoimmunity mainly as autoantibody-producing cells. To investigate the possible role of these cells in myasthenia gravis, we studied the numbers of CD5 + B cells, CD5+ B cells, and CD19+ B cells as well as CD5+ T cells in the peripheral blood from 31 patients with myasthenia gravis and 31 healthy individuals. Both absolute percentages (percent of peripheral blood mononuclear cells) and relative percentages (percent of total CD19+ B cells) of CD5+ B cells were the same in patients as in controls. The numbers of CD5+ B cells and CD19+ B cells were the same in both groups, whereas CD5+ T cells were lower in the patients. There was no correlation between clinical stage, sex, thymectomy, or pathology of thymus and the levels of CD5+ B cells, CD5+ B cells, or CD19+ B cells. Patients treated with azathioprine had lower levels of CD5+ B cells than untreated patients and controls. Our results show that patients with myasthenia gravis have the same levels of CD5 + B cells as healthy individuals.

Oxidation and scavenger receptor-mediated uptake of low density lipoprotein (LDL) in intimal macrophages are believed to be key events in the development of atherosclerosis. We report here that oxidized LDL increases DNA synthesis, expression of HLA-DR, and interleukin-2 receptors in T cells. The stimulatory effect of oxidized LDL was not due to a direct effect on T cells but required the presence of monocytes. Oxidized LDL also stimulated the release of interleukin-1 beta from monocytes. The maximal effect of oxidized LDL on T-cell activation and interleukin-1 beta release occurred at a concentration of 1 micrograms/ml. Native LDL also had the capacity to activate T cells, although only at higher concentrations. The stimulatory effect of both native and oxidized LDL was inhibited by superoxide dismutase. Monocytes as well as T cells were found to have the ability to oxidize LDL, suggesting that the stimulatory effect of native LDL may arise as a result of LDL oxidation during incubation with monocytes and T cells. The results suggest that oxidized LDL may activate T cells in atherosclerotic lesions.

To determine the extent of V-gene heterogeneity of blood T lymphocytes in patients suffering from Myasthenia Gravis (MG), we used eight recently available monoclonal antibodies (MoAb), directed against different V alpha and V beta gene products of the variable part of the T-cell receptor (TCR), covering approximately 25% of the alpha/beta T cells in normal peripheral blood (PBL) of healthy individuals. Using a two-colour immunofluorescence method, we could calculate the expression of alpha/beta V segments within the two major T-cell subsets, CD4-/CD8+ and CD4+/CD8- lymphocytes. Twenty-seven per cent (4/15) of the MG patients had T cells showing signs of abnormal expansion. Furthermore, among these expanded T cells, a restricted V beta 12 gene expansion could be seen, in three out of four patients. No correlation between TCR V-gene usage and HLA haplotypes (HLA-A, -B, -DR and -DQ) could be seen. Our data suggest that the majority of MG patients have abnormally expanded T-cell clones. The relevance of these findings is discussed.

In vitro functional properties of peripheral blood mononuclear cells were evaluated in 29 patients with myasthenia gravis and in 11 healthy controls. Spontaneous cell proliferation was higher in patients than in controls. The production of interleukin-2 and interferon-gamma and the proliferative response to different mitogens were reduced in the patients. A positive correlation was found between the production of interleukin-2 and interferon-gamma. These defects in T cell function were the most pronounced in nonthymectomized patients. Patients with severe disease had a higher percentage of cells bearing the interleukin-2 receptor and a higher spontaneous production of tumor necrosis factor alpha in cell culture than in patients with mild disease. There was no difference between patients and controls in the level of soluble interleukin-2 receptor in cell culture supernatants or in sera. The results indicate a partially suppressed T cell function in myasthenia gravis. This defect was less pronounced in patients studied after thymectomy.

The production of anti-idiotypic antibodies from Epstein-Barr virus transformed peripheral blood lymphocytes was analysed in 12 patients with multiple myeloma and monoclonal gammopathy of undetermined significance. A low anti-idiotype production was found in patients with advanced disease (multiple myeloma stage III), whereas the production was high in patients with multiple myeloma stage I and monoclonal gammopathy of undetermined significance (MGUS) (P less than 0.01). The study supports the existence of an immunological network response in patients with monoclonal gammopathies.

Lymphocytes from two patients with multiple myeloma stage I and one patient with monoclonal gammopathy of undetermined significance were found to proliferate specifically in response to low concentrations of F(ab′)2 fragments of the autologous M component. T cell clones isolated from repeatedly stimulated cultures bound specifically the autologous idiotype and proliferated after addition of soluble idiotype and exogenous interleukin-2. The majority of clones were CD8+ and showed negligible staining for CD4. Idiotype-binding clones could not be isolated from cultures of lymphocytes from a healthy control stimulated under the same conditions. The study provides support for the existence of idiotype-reactive T cells in monoclonal gammopathies. Such cells might have a regulatory role on the tumour cell clone and may be important for a future therapeutic approach.

✓ The fluid of cystic brain tumors was characterized with regard to the protein content. In most malignant tumors, the concentrations of immunoglobulins G and M (IgG and IgM) were higher relative to other proteins in the cyst fluid than in the serum of the same patient. A markedly elevated ratio of monomeric to pentameric IgM was detected in the cyst fluid of two patients with glioblastomas. The results indicate a local immunoglobulin synthesis in malignant cystic brain tumors. It is hypothesized that higher-than-expected concentrations of IgG and IgM in cyst fluid as compared to plasma are a sign of an ongoing immune response triggered by the tumor.

Serum from patients with myasthenia gravis (MG) contain antibodies to numerous skeletal muscle components in addition to the acetylcholine receptor (AChR). Certain non-AChR skeletal muscle autoantibodies have been shown by absorption to cross-react with cardiac muscle, leading to the designation of ‘skeletal and heart’ or SH antibodies. This study describes a new procedure for the extraction of human cardiac muscle which allows direct determination of SH antibody reactivity. Serologic evaluation of 17 patients with MG revealed 9 17 (53%) were seropositive for SH antibody to cardiac muscle. Absorption of selected MG serum samples with cardiac muscle extracts, reduced or eliminated reactivity to skeletal muscle in all cases, confirming the presence of cross-reactive antibodies. Immunoblot analysis of cardiac muscle extracts demonstrated several distinct antigenic components, which were unrelated to the acetylcholine receptor or to previously identified striatonal muscle proteins. Serum samples from individual MG patients displayed different immunoblot reactivity patterns to the antigens in cardiac muscle extracts, providing the first evidence of multiple heart-reactive SH antibodies in MG.

The development of inhibitory antibodies is a severe and costly complication to replacement therapy occurring in 10–15% of patients with hemophilia A, and the aim of the Malmo International Brother Study (MIBS) is to evaluate host genetic factors associated with this adverse effect of treatment. In the present study, factor VIII mutations, HLA genotypes and polymorphisms of the interleukin IL-1beta, IL-4 and IL-10 genes known to influence antibody production in autoimmune diseases, were analyzed in 164 patients with hemophilia A (120 severe, 30 moderate and 14 mild) belonging to 78 unrelated families. Seventy-seven (47.0%) of the subjects had a history of inhibitors (57 high-responding, 20 low-responding) in 54 unrelated families (34 discordant, 20 concordant siblings). In 24 families, no inhibitor was reported in any of the siblings. Seventy-five patients (45.7%) in 36 families had an inversion. In this group, 40 patients (53.3%) in 28 families had inhibitors (17 concordant, 11 discordant). Weak associations between inhibitor development and the HLA alleles A26 and B44 were found. No association was found with the IL-1beta Taq 1 RFLP alleles in exon 5, and the −590 C/T SNP in the promoter region of IL-4. There was however, a strong association between an allele with 134 bp in one of the CA repeat microsatellites, IL-10G, located in the promoter region of the IL-10 gene, and development of inhibitor. Allele 134 was found in 32 (41.6%) of the patients with inhibitors compared with 12 (13.8%) of the inhibitor negative patients (p

The automated turbidimetric method presented allows a fast and accurate quantitation of plasma proteins. The analysis requires somewhat more antiserum than the radial immunodiffusion and the electroimmunoassay. However, this is compensated for by more rapid results and lower labour cost. The reference values for albumin, haptoglobin and IgG are the same as obtained by other immunological methods. The correlations with radial immunodiffusion and electroimmunoassay are good within the normal range. At high monoclonal IgG concentrations this method is better correlated to dye binding properties (scanning of electropherograms) than is the electroimmunoassay.

Clinical Observations. A total of 53 MG patients have been treated with different immunosuppressive methods (alone or combined) with the following effects: Thymectomy was performed in 38 patients. The improvement was excellent in 15, and moderate or uncertain in 20. In three patients severe long-lasting deterioration followed the operation. ACTH treatment (n=32): Initial deterioration during the 5-7 days of heavy ACTH treatment (1000 IU) was followed by an improvement lasting on an average 4 months. The improvement was good or moderate in 78% of the patients. Betamethazone treatment has been tried in six patients where ACTH and azathioprine was ineffective. In four of these patients the results were excellent. Azathioprine treatment has been given to 26 patients for periods up to 7 years. An improvement is measurable after 6-12 weeks and it seems maximal after about 1 year. Of the 26, 80% responded favorable with reduction in the need for cholinesterase inhibitors. Severe complications were seen in three patients with one death. Drainage of thoracic duct lymph was initiated in 14 patients up to 4 weeks with rapid improvement lasting as long as drainage was performed. Long-termed effects of the drainage may be present, however. Retransfusion of homologous cell-free lymph precipitated a return of the myasthenic symptoms. Biochemical Studies on Myasthenic Lymph. Using a membrane preparation from the electric organ from Torpedo marmorata and tritiated Naja naja siamensis neurotoxin we demonstrated a decreasing binding of toxin to the receptor in the presence of MG lymph gamma-globulin fraction. Gammaglobulins from controls showed almost no inhibition of the neurotoxin binding. Immunological Studies. An increased frequency of HL-A1 and 8 was found in female patients. LD typing was also performed. During a period of three weeks of thoracic duct drainage 130X10(9) or about 10% of total number of lymphocytes in the body were removed. In the lymph an initial decrease in the proportion of thymus-derived lymphocytes (T cells) occurred, which was accompanied by a sequent increase in the proportion of bone-marrow-derived lymphocytes (B cells). Towards the end of drainage this effect was reverted. Mitogenic stimulation using lymphocytes from thoracic duct drainage revealed no differences as compared to normal cells. The proportions of T and B cells was studied in the peripheral blood in nine patients treated with ACTH. During treatment there was an initial decrease in the proportion of T cells accompanied by a subsequent rise in the proportion of B cells, which was maximal after 3-10 days. These proportions were reverted to normal 1-5 days after the maximal change. The effect of azathioprine on T and B cells has also been studied.

A pair of identical twins, 47 years of age, who have been discordant for myasthenia gravis for 15 years were studied with regard to clinical status, neuromuscular function, and presence and properties of myasthenia specific autoantibodies. The autoantibody repertoire was tested in serum, as produced by peripheral lymphocytes in culture and as revealed by B cell lines. The healthy twin had no clinical signs of myasthenia and no signs of impaired neuromuscular function on electrophysiological tests. The autoantibody repertoire and the avidity of the anti-receptor antibodies were similar in both individuals. Epstein-Barr virus transformation of peripheral lymphocytes revealed a higher incidence of B cells committed to make autoantibodies in the healthy twin than in her myasthenic sister.

Fifty-eight first-degree relatives to 40 patients with myasthenia gravis were investigated regarding presence of acetylcholine receptor antibodies, anti-idiotypic antibodies against the receptor antibodies and clinical and electrophysiological signs of disturbed neuromuscular function. No relative had clinical signs of muscle weakness. The prevalence of low concentrations of receptor antibodies was 54%, of anti-idiotypic antibodies 37% and of pathological and borderline single fibre EMG 45%. No sibling, only 2/11 children and 3/14 parents were normal in all three tests. A combination of receptor antibodies and anti-idiotypic antibodies was the most common finding and was especially frequent in children. In female siblings and children there was a positive correlation between the presence of HLA-antigen A1 and/or B8 and that of receptor antibodies and anti-idiotypic antibodies. Male siblings and children showed no such correlation but had a higher frequency of pathological single fibre EMG than females.

Aspects of acetylcholine receptor immunology and circulating receptor antibodies are reviewed with regard to both human and experimental myasthenia gravis. Receptor antibodies that have negligible cross-reactivity with skeletal muscle receptor can nonetheless cause destruction of the postsynaptic motor endplate area. Antibodies to mammalian skeletal muscle receptor can bind in-situ receptors. Transfer of myasthenic IgG increases neurophysiologic symptoms in rabbits showing slight signs of experimental myasthenia gravis, suggesting a block of in-situ receptors. Determination of receptor antibodies using RIA tests and partially purified human skeletal muscle receptor has been evaluated in the diagnosis of myasthenia gravis. Ninety percent of Swedish myasthenic patients in one study were found to have receptor antibodies. A rough correlation has been found between antibody titer and the severity of disease. Immunosuppressive treatment and thymectomy decrease the titer. In patients with thymoma, high antibody titers remain. When taken together, antibody-titer determination and electrophysiologic tests--particularly single-fiber electromyography--are very valuable diagnostic tools.

Neuromuscular transmission and the staircase phenomenon in the adductor pollicis muscle were studied in six patients with myasthenia gravis before and 24 hours after single plasma exchanges given in short series over one to four weeks. An improvement in neuromuscular transmission was observed in all patients but one within 24 hours, suggesting that an immunological block of receptor sites is reversible or that acetylcholine receptors are rapidly resynthesized. In addition to a neuromuscular transmission defect, two of the patients also showed evidence of impaired excitation-contraction coupling with a negative staircase phenomenon and reduced posttetanic twitch potentiation. This condition became normal after plasma exchange, which may indicate that a reversible immunological impairment of the sarcoplasmic reticulum was present. Improvement lasted up to several months. The anti-acetylcholine receptor antibody titers were lowered in response to single plasma exchanges, but actual titer levels showed poor correlation with clinical and electrophysiological changes.

The B-cell repertoire in a patient with benign monoclonal gammopathy of unknown significance was studied using Epstein-Barr virus transformation of peripheral lymphocytes. The presence of anti-idiotypic B cells producing monoclonal antibodies that reacted with idiotypic determinants on the monoclonal immunoglobulin was verified. The two monoclonal anti-idiotypic antibodies studied were of the IgM-kappa type. Such anti-idiotypic antibodies may be part of an idiotypic network regulation of the monoclonal B-cell population.

Anti-acetylcholine receptor antibody associated idiotypes were defined by six murine monoclonal antibodies raised against purified receptor antibodies. Four of the monoclonal antibodies bound to idiotopes located within or close to the antigen binding site of the anti-receptor antibodies; the other two monoclonal antibodies were directed against framework determinants. These monoclonal antibodies recognized idiotopes present on immunoglobulins in 14-60% of patients presenting myasthenia gravis, indicating substantial idiotype sharing. These idiotopes were also found in patients with no detectable anti-receptor antibody activity in their serum. In all patients studied, the pattern of idiotypes fluctuated considerably during the course of the disease regardless of clinical symptoms. This suggests continuous modulation of the autoimmune process in myasthenia gravis.

Forty patients with myasthenia gravis were HLA tissue typed and the amount of anti-acetylcholine receptor protein antibody determined. Sera from seven patients were tested for antibody titer by repeated determinations and the serum concentration was found to be stable. Patients with thymoma had higher titers than patients with normal thymus histology or hyperplasia. Individuals with thymoma lacking HLA-B8 were found to have a higher concentration of antibodies than HLA-B8 negative individuals with hyperplasia. No statistically significant differences were obtained when comparing the amount of antibody in HLA-B8 positive and negative individuals. Titers in patients subjected to thymectomy more than 8 years before sampling did not deviate from those in non-thymectomized myasthenics.

Spontaneous and pokeweed mitogen-induced production of specific autoantibodies were studied in cultures of peripheral blood mononuclear cells from patients with different clinical stages of myasthenia gravis. Receptor antibody-related idiotypes and anti-idiotypic antibodies were defined by binding to mouse monoclonal anti-idiotypic and anti-receptor antibodies, respectively. Patients with severe disease had a more complete spectrum of idiotypes in serum, and cells from such patients spontaneously produced more antibody species and higher concentration of both idiotypes and anti-idiotypes than patients with mild disease. The frequencies of antibody specificities in tissue culture supernatants more closely reflected disease activity than those in serum. Tissue culture for the study of different species of autoantibodies has proved to be a useful tool for monitoring the disease and the effects of treatment.

A 50-year-old woman with muscular fatigue and monoclonal gammopathy of unknown significance was shown to have high levels of antibodies against the acetylcholine receptor of the skeletal muscle endplate. The specific antibody activity was exclusively associated with the monoclonal component. There were no objective signs of myasthenia gravis. This is the first reported case with antibody activity against the acetylcholine receptor found in a monoclonal immunoglobulin fraction.