Concordance between radioimmunoassay and fixed cell-based assay in subjects without myasthenia gravis: optimizing the diagnostic approach

Silvia Falso, S. Marini, Cinzia Carrozza, E. Sabatelli, G. Mascagna, Martina Marini, J. Morroni, Amelia Evoli Stampanoni-B, Raffaele Iorio

Risultato della ricerca: Contributo in rivistaArticolo in rivista

Abstract

Background and Purpose: Acetylcholine receptor antibody (AChR-Ab) detection is crucial in myasthenia gravis (MG) diagnosis and, currently, the radioimmunoassay (RIA) is the gold standard. However, RIA may detect AChR-Ab against nonpathogenic intracellular epitopes. In this study, we performed fixed cell-based assay (F-CBA) in RIA-AChR-Ab positive subjects without MG symptoms, to assess whether F-CBA could show a higher specificity compared to RIA in detecting pathogenic Abs. Methods: We reviewed medical records of patients referred to our MG outpatient clinic because of RIA-AChR-Ab detection. MG diagnosis was based on clinical examination, electrophysiology and Ab detection. AChR-Abs were tested by RIA in the whole cohort. Serum samples from RIA-positive asymptomatic subjects were retested by F-CBA. Results: Of 605 subjects who tested RIA-AChR-Ab positive, MG diagnosis was confirmed in 599. Six subjects were RIA-AChR-Ab positive although they had never had MG symptoms; in four of these subjects AChR-Abs were not detected by F-CBA, whereas the remaining two (both non-MG thymoma cases) were positive also by F-CBA. Conclusions: RIA false positivity for AChR-Ab is very rare. Previous literature has demonstrated that F-CBA has higher sensitivity than RIA for MG, especially in ocular cases. Our preliminary results show that, in rare instances, F-CBA may be more specific than RIA for MG diagnosis.
Lingua originaleEnglish
pagine (da-a)N/A-N/A
RivistaEuropean Journal of Neurology
Volume31
DOI
Stato di pubblicazionePubblicato - 2024

Keywords

  • autoantibodies
  • autoimmune
  • neuromuscular junction
  • nervous system
  • diagnostic tests

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