title: Eliminating false-positive results in serum tests for neuromuscular autoimmunity.
abstract: In this study we describe the false-positive frequency in radioimmunoprecipitation assays for muscle acetylcholine receptor (AChR) and neuronal voltage-gated potassium channel (VGKC) autoantibodies, attributable to 125I-ligand immunoprecipitation. Sera were evaluated for AChR autoantibody (n = 34,095) and VGKC autoantibody (n = 11,028). We retested sera that yielded apparently positive results with 125I-ligand with and without detergent-solubilized cation-channel protein, indentified clinically validated fals-positive rates of 0.05% and 1.7% for AchR and VGKC autoantibodies, respectively. Specificity assurance in radioimmunoprecipitation assays requires subtraction of values for 125I-ligand binding.
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Metha
authors.initials: M
authors.lastname: Apiwattanakul
authors.forename: Andrew
authors.initials: A
authors.lastname: McKeon
authors.forename: Sean J
authors.initials: SJ
authors.lastname: Pittock
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Kryzer
authors.forename: Vanda A
authors.initials: VA
authors.lastname: Lennon
mesh_terms: D001323:Autoantibodies / Q000032:analysis / Q000097:blood*; D020274:Autoimmune Diseases of the Nervous System / Q000097:blood* / Q000175:diagnosis* / Q000276:immunology; D001667:Binding, Competitive / Q000502:physiology; D003902:Detergents / Q000737:chemistry; D003951:Diagnostic Errors / Q000517:prevention & control; D005189:False Positive Reactions; D006801:Humans; D007457:Iodine Radioisotopes; D008024:Ligands; D020511:Neuromuscular Junction Diseases / Q000097:blood* / Q000175:diagnosis* / Q000276:immunology; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry / Q000276:immunology; D011237:Predictive Value of Tests; D015531:Radioimmunoprecipitation Assay / Q000379:methods* / Q000592:standards; D011950:Receptors, Cholinergic / Q000276:immunology; D012680:Sensitivity and Specificity; D012995:Solubility
chemical_list: D001323:Autoantibodies; D003902:Detergents; D007457:Iodine Radioisotopes; D008024:Ligands; D024642:Potassium Channels, Voltage-Gated; D011950:Receptors, Cholinergic