Strain differences in the autoimmune response of mice to acetylcholine receptors.
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In this 'double-blind', randomized, placebo-controlled phase II trial, we compared an altered peptide ligand of myelin basic protein with placebo, evaluating their safety and influence on magnetic resonance imaging in relapsing-remitting multiple sclerosis. A safety board suspended the trial because of hypersensitivity reactions in 9% of the patients. There were no increases in either clinical relapses or in new enhancing lesions in any patient, even those with hypersensitivity reactions. Secondary analysis of those patients completing the study showed that the volume and number of enhancing lesions were reduced at a dose of 5 mg. There was also a regulatory type 2 T helper-cell response to altered peptide ligand that cross-reacted with the native peptide.
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In the K/BxN mouse model of rheumatoid arthritis, the transfer of autoantibodies specific for glucose-6-phosphate isomerase (GPI) into naïve mice rapidly induces joint-specific inflammation similar to that seen in human rheumatoid arthritis. The ubiquitous expression of GPI and the systemic circulation of anti-GPI immunoglobulin G (IgG) seem incongruous with the tissue specificity of this disease. By using PET (positron emission tomography), we show here that purified anti-GPI IgG localizes specifically to distal joints in the front and rear limbs within minutes of intravenous injection, reaches saturation by 20 min and remains localized for at least 24 h. In contrast, control IgG does not localize to joints or cause inflammation. The rapid kinetics of anti-GPI IgG joint localization supports a model in which autoantibodies bind directly to pre-existing extracellular GPI in normal healthy mouse joints.
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Microsomal antibodies and antibodies directed toward the receptor for thyroid-stimulating hormone (TSH) decreased in parallel while patients with Graves' disease were taking carbimazole, whereas no significant changes were observed during treatment with placebo or propranolol. The changes in autoantibody levels during carbimazole treatment were independent of changes in serum thyroxine and could have been due to a direct effect of the drug on autoantibody synthesis. Evidence for this suggestion was provided when low doses of methimazole (the active metabolite of carbimazole) were found to inhibit thyroid-autoantibody production in cultured lymphocytes. Since thyroid lymphocytes are probably a major site of thyroid-antibody synthesis in Graves' disease and methimazole is concentrated in the thyroid during treatment, a local action of the drug on antibody production seems likely. This possibility could be important in the use of carbimazole to control hyperthyroidism.
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The immunoglobulin (Ig) class and IgG subclasses of autoantibodies to commercial VDRL antigen, creatine kinase (CK), and fibronectin (Fn) in the sera of patients with various stages of syphilis were quantified using solid-phase radioimmunoassays (RIA) and ELISA. Sera from patients with active secondary syphilis, initially positive for anti-Fn and anti-CK autoantibodies by RIA, were re-evaluated by ELISA using monoclonal antibodies (MoAb) for detection of human Ig class and subclass responses. Results of these assays revealed that anti-Fn and anti-CK responses were not only IgG in nature, but dramatically skewed to IgG1 and IgG3 subclasses. While the restricted, co-expression of these isotypes seemingly paralleled anti-treponemal activity, inverse relationships actually existed between the subclass responses to Fn and those to Treponema pallidum. In contrast, anti-VDRL were predominantly IgM in 17 of 22 patients. Of those sera exhibiting detectable anti-VDRL IgG activity, responses appeared to be restricted to IgG1. These results suggest that different control mechanisms may be responsible for regulation of the various autoantibody responses expressed during syphilitic infection.
The C terminal region of a Trypanosoma cruzi ribosomal P protein, encoded by the lambda gt11 JL5 recombinant, defined a major antigenic determinant in chronic Chagas heart disease. Immunopurified anti-JL5 antibodies were tested for anti-human ribosome reactivity by immunoblotting. They recognized the parasite ribosomal P proteins and clearly reacted with the corresponding human P proteins. The peptide R-13, that comprises the 13 C terminal residues of the JL5 recombinant and defines the specificity shared between chronic Chagas heart disease anti-JL5 antibodies and the systemic lupus erythematosus (SLE) anti-P antibodies, was used to study the specificity and the IgG subclass distribution of the anti-R-13 response by ELISA. The R-13 autoepitope is recognized mainly by sera from chagasic patients, but not by sera from malaria patients. Moreover, there was a significant correlation between anti-R-13 antibody levels and anti-T. cruzi antibody titres. The anti-R-13 response was mainly restricted to the IgG1 heavy chain isotype and correlated with the anti-T. cruzi isotype distribution.
Autoantibodies against myeloperoxidase and elastase were found in a study of nine patients who had developed glomerulonephritis after treatment with hydralazine, but not in patients who were treated with hydralazine without side-effects. Circulating IgM isotype antibodies against myeloperoxidase, and IgM and IgG anti-elastase, were mainly present during the initial months after withdrawal of the drug. By contrast, IgG isotype antibodies against myeloperoxidase, initially found in seven patients, had increased in concentration and were present in all patients at follow-up after 4-12 years.
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Pretreatment of rats with low doses of purified fraction of rat male accessory glands (containing the autoantigen) markedly reduced the immune response to autoantigen when animals were subsequently challenged with modified rat male accessory glands in complete Freund's adjuvant. The rats pretreated with low doses of antigen prior to immunization showed marked suppression of delayed-type hypersensitivity reaction (P less than 0.001) when compared to control animals (pretreated with rat lung saline extract or 0.15 M NaCl). There was also enhancement of migration of macrophages in test male rats, whereas the migration was inhibited in control male rats (P less than 0.01). The stimulation of migration found in the male rats in which the response was inhibited would suggest the presence of a migration stimulation factor, which is considered a marker of suppressor cell activity. Humoral immunity was also reduced. Pretreatment of rats with low doses of the antigen markedly reduced the immune response, probably because of the induction of suppressor cells.
OBJECTIVES: To determine the significance of anti-laminin antibodies in patients with collagen vascular diseases using a large control population of normal individuals. METHODS: Anti-laminin antibodies of IgG isotypes were determined using an ELISA assay in a population consisting of 73 patients with systemic sclerosis, 10 with urticarial vasculitis, five with leukocytoclastic vasculitis, 13 with giant cell arteritis, and eight with dermatomyositis. Sera from 134 healthy individuals served as controls. RESULTS: Only eight sera in the systemic sclerosis group, one in the leukocytoclastic group and one in the giant cell arteritis group were abnormal. No other sera were abnormal. CONCLUSION: These data contradict previous studies using smaller numbers of controls. The necessity for an adequate control population to define abnormal when comparing immune responses among groups is frequently under-emphasised in rheumatological studies.
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The ability to induce antibodies to rat male accessory glands in male and female rats was demonstrated, but a higher response with wider specificity was revealed in female animals. In order to investigate whether this different response may be influenced by sexual hormones we castrated male and female rats at 4 or 30 days after birth. After that we studied the course and specificity of their humoral response to male accessory glands comparing them with that of sham-operated, sex-matched, littermate controls. Orchidectomy in male or oophorectomy in female rats changed neither the course nor specificity of humoral immune response. We conclude, therefore, that hormonal factors do not play any important role in the experimental model under study.
An immunodominant and potentially pathogenic epitope associated with bullous pemphigoid (BP) and herpes gestationis (HG) has recently been mapped by our laboratory to a noncollagenous stretch of the extracellular domain of the human BP180 antigen. This antigenic site, designated the MCW-1 epitope, has been shown to be recognized by the majority of BP and HG sera. Interestingly, the MCW-1 epitope is absent from the murine BP180 molecule, and therefore, human autoantibodies directed against this site could not be tested for pathogenicity using the conventional passive transfer mouse model. Alternatively, rabbit antibodies were prepared against recombinant forms of the human MCW-1 epitope and the murine NC16A domain and were tested for pathogenicity by passive transfer experiments. Neonatal mice injected with rabbit antimurine BP180 IgG developed a subepidermal blistering disease that closely mimicked BP and HG at the clinical, histological and immunological levels. Rabbit IgG specific for the human MCW-1 epitope was not pathogenic. These results suggest that the autoantibodies against the MCW-1 epitope of the human BP180 antigen found in BP and HG sera may be relevant in the pathogenesis of blister formation in these patients.
Levels of anti-Ku (p70/p80) antibodies were measured longitudinally in sera from four individuals with systemic lupus erythematosus or related disorders. Antibodies to the native Ku antigen (p70/p80 complex) varied over a range of up to 577-fold. Large fluctuations were also observed in the levels of autoantibodies to several distinct epitopes of the Ku (p70/p80) antigen. Levels of these individual autoantibody populations generally paralleled one another, suggesting that they are coordinately regulated. A similar pattern of anti-DNA antibody fluctuation was seen in some sera. To examine the possibility that these autoantibodies were generated by polyclonal B cell activation, the levels of anti-Ku (p70/p80) and anti-DNA antibodies were compared to the levels of antibodies to Escherichia coli proteins, tetanus toxoid, and bovine insulin, transferrin, cytochrome c, serum albumin, and thyroglobulin. In sera from the same individual, anti-Ku (p70/p80) antibodies were sometimes produced in the complete absence of polyclonal activation, and at other times were accompanied by increased polyclonal activation. Anti-DNA antibody levels more closely paralleled the level of polyclonal activation than did the anti-Ku (p70/p80) levels. These studies suggest that anti-Ku (p70/p80) antibodies are generated by an antigen-selective mechanism, but that polyclonal activation frequently, although not invariably, accompanies autoantibody production. This observation is consistent with the possibility that polyclonal activation might be secondary to autoantibody production.
To gain insight into the mechanisms of autoantibody induction, sera from 40 patients with systemic lupus erythematosus (SLE) were tested by ELISAs for antibody binding to denatured individual histones, native histone-histone complexes, histone-DNA subnucleosome complexes, three forms of chromatin, and DNA. Whole chromatin was the most reactive substrate, with 88% of the patients positive. By chi-square analysis, only the presence of anti-(H2A-H2B), anti-[(H2A-H2B)-DNA], and antichromatin were correlated with kidney disease measured by proteinuria > 0.5 g/d. SLE patients could be divided into two groups based on their antibody-binding pattern to the above substrates. Antibodies from about half of the patients reacted with chromatin and the (H2A-H2B)-DNA subnucleosome complex but displayed very low or no reactivity with native DNA or the (H3-H4)2-DNA subnucleosome complex. An additional third of the patients had antibody reactivity to chromatin, as well as to both subnucleosome structures and DNA. Strikingly, all sera that bound to any of the components of chromatin also bound to whole chromatin, and adsorption with chromatin removed 85-100% of reactivity to (H2A-H2B)-DNA, (H3-H4)2-DNA, and native DNA. Individual sera often bound to several different epitopes on chromatin, with some epitopes requiring quaternary protein-DNA interactions. These results are consistent with chromatin being a potent immunogenic stimulus in SLE. Taken together with previous studies, we suggest that antibody activity to the (H2A-H2B)-DNA component signals the initial breakdown of immune tolerance whereas responses to (H3-H4)2-DNA and native DNA reflect subsequent global loss of tolerance to chromatin.