Acetylcholine receptor antibodies in primary biliary cirrhosis: characterization of antigen and idiotypic specificity.
Auto-antibodies against the acetylcholine receptor of skeletal muscle are considered to be the cause of the neuromuscular dysfunction in myasthenia gravis. However, such auto-antibodies also occur in disease states not accompanied by neuromuscular symptoms. Patients with primary biliary cirrhosis have a high prevalence of different auto-antibodies, including antibodies against the acetylcholine receptor. In primary biliary cirrhosis, these anti-receptor antibodies are predominantly of IgM isotype. The IgM antibodies show a broader reactivity with receptors from other species than antibodies from myasthenic patients. Immunoglobulins from patients with primary biliary cirrhosis bear the same receptor antibody-associated idiotypes, but the repertoire is quantitatively different from that found in myasthenia gravis patients. The IgM receptor antibody activity in a serum from a patient with primary biliary cirrhosis could be inhibited by cardiolipin, poly[dT], poly[I], and ssDNA, whereas this antibody activity in serum from a patient with myasthenia gravis was slightly reduced only by cardiolipin. Generally, IgM antibodies from patients with primary biliary cirrhosis had a broader reactivity with polynucleotides and phospholipids than IgG antibodies and antibodies from patients with myasthenia gravis. These results indicate a difference in the fine specificity between acetylcholine receptor antibodies in primary biliary cirrhosis and in myasthenia gravis.
Department of Medicine, Karolinska Hospital, Stockholm, Sweden.
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Sundewall
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Lefvert
D000818:Animals; D001323:Autoantibodies / Q000032:analysis*; D000939:Epitopes / Q000032:analysis*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D007130:Immunoglobulin Idiotypes / Q000276:immunology*; D007075:Immunoglobulin M / Q000032:analysis*; D008105:Liver Cirrhosis, Biliary / Q000276:immunology*; D051379:Mice; D011950:Receptors, Cholinergic / Q000276:immunology*; D014101:Torpedo
D001323:Autoantibodies; D000939:Epitopes; D007074:Immunoglobulin G; D007130:Immunoglobulin Idiotypes; D007075:Immunoglobulin M; D011950:Receptors, Cholinergic