Evidence for the presence of immunoreactive acetylcholine receptors on human thymus cells.
Triton extracts from thymuses and thymomas from either normal subjects or MG patients specifically bind [125I] alpha-bungarotoxin (alpha Bgt). This binding is saturable (apparent Ks = 5.9 X 10(-9) M) and can be inhibited by cold alpha Bgt, acetylcholine or nicotinic agonists. These results demonstrate the presence on human thymus cells of acetylcholine receptor (ACh.R), 2.8% for normal human thymus in regard of ACh.R concentration in human muscle. Normal human thymic extracts were used as an antigen source in the radioimmunoassay for the detection of anti-ACh.R antibodies in positive MG patients' sera. 72% of these sera were also positive with the thymic antigen. The demonstration of ACh.R in human thymus brings further support to the hypothesis of intrathymic autosensitivity against ACh.R as a major factor in MG pathogenesis.
D000906:Antibodies / Q000032:analysis; D000941:Antigens / Q000032:analysis; D002038:Bungarotoxins / Q000378:metabolism; D000939:Epitopes; D006801:Humans; D009157:Myasthenia Gravis / Q000276:immunology / Q000473:pathology; D011092:Polyethylene Glycols / Q000276:immunology; D011950:Receptors, Cholinergic / Q000276:immunology*; D013945:Thymoma / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology*; D013953:Thymus Neoplasms / Q000276:immunology
D000906:Antibodies; D000941:Antigens; D002038:Bungarotoxins; D000939:Epitopes; D011950:Receptors, Cholinergic; D011092:Polyethylene Glycols