Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Sep;93(9):995-1000.
doi: 10.1136/jnnp-2022-329284. Epub 2022 Jul 14.

Clinical value of cell-based assays in the characterisation of seronegative myasthenia gravis

Valentina Damato  1   2   3 , Gregorio Spagni  4   5 , Gabriele Monte  4   6 , Mark Woodhall  7 , Leslie Jacobson  7 , Silvia Falso  4 , Thomas Smith  7 , Raffaele Iorio  5 , Patrick Waters  3   7 , Sarosh R Irani  3   7 , Angela Vincent  7 , Amelia Evoli  4   5
Affiliations

Clinical value of cell-based assays in the characterisation of seronegative myasthenia gravis

Valentina Damato et al. J Neurol Neurosurg Psychiatry. 2022 Sep.

Abstract

Objective: Patients with myasthenia gravis without acetylcholine receptor (AChR) or muscle-specific kinase (MuSK) antibodies detected by radioimmunoprecipitation assays (RIAs) are classified as seronegative myasthenia gravis (SNMG). Live cell-based assays (l-CBAs) can detect additional antibodies to clustered AChR, MuSK and low-density lipoprotein receptor-related protein 4 (LRP4), but positivity rates are variable and both clinical relevance and utility of CBA platforms remain unclear.

Methods: Sera from 82 patients with SNMG were tested by l-CBAs. Human embryonic kidney cells were transfected to individually express clustered AChR, MuSK or LRP4; or transfected to jointly express both clustered adult AChR and MuSK. Sera from 30 and 20 patients positive by RIA for AChR or MuSK antibodies were used as comparators.

Results: 53 of 82 (72%) patients with SNMG had generalised and 29 (28%) had ocular disease. The clustered AChR CBA detected antibodies in 16 of 82 patients (19.5%; including 4 patients with solely fetal AChR antibodies), while 7 of 82 (8.5%) patients had MuSK antibodies. A novel exploratory combined adult AChR-MuSK l-CBA efficiently detected all these antibodies in a subset of the SNMG cohort. No LRP4 antibodies were identified. Overall, patients with SNMG with clustered AChR antibodies, CBA-positive MuSK-MG or triple seronegative were younger, had less severe disease than patients with RIA-positive MG and had a better clinical outcome when immunotherapy was started soon after disease onset, although the time interval from onset to immunotherapy was not different when compared with patients with RIA-positive MG.

Conclusion: Around one-third of patients with SNMG had AChR or MuSK antibodies by l-CBAs, which were efficiently detected with a combined l-CBA. The results in this large and unselected cohort of patients with MG demonstrate the diagnostic usefulness of performing CBAs and the importance of making these tests more widely available.

Keywords: MYASTHENIA; NEUROIMMUNOLOGY; NEUROMUSCULAR.

PubMed Disclaimer

Conflict of interest statement

Competing interests: AV and the University of Oxford held a patent for detection of MuSK antibody assays (expired 2020), licensed to Athena Diagnostics; AV received a proportion of royalties. SRI and PW are co-applicants and receive royalties on patent application WO/2010/046716 entitled ‘Neurological Autoimmune Disorders’ (the patent has been licensed for the development of assays for LGI1 and other VGKC-complex antibodies) and have filed two other patents regarding autoantibody diagnostic algorithms.

Publication types

Substances

LinkOut - more resources