Live cell-based assays (l-CBAs) may be useful in the diagnosis and characterization of some cases of myasthenia gravis (MG), according to a study recently published in the Journal of Neurology, Neurosurgery and Psychiatry.

“Our findings validate the addition of CBAs to the diagnostic work-up of MG as they can speed up the serological confirmation in radioimmunoprecipitation assay-negative patients, prompting treatment decisions and improving outcome,” the authors explained.

The study included 82 patients previously diagnosed with MG and classified as seronegative (SNMG), out of which 72% had the generalized form of the disease and 28% had the ocular form. All participants underwent l-CBAs, detecting clustered acetylcholine receptor (AChR) antibodies and muscle-specific kinase (MuSK) antibodies in 19.5% and 8.5% of the cases, respectively. Although also tested, no patient had detectable lipoprotein receptor-related protein 4 antibodies during the essay. 

Read more about MG testing

Interestingly, individuals with a triple negative result were overall younger, with milder disease, and showcased better clinical outcomes after initiating immunotherapy. 

Although l-CBAs have been previously described as a tool for determining AChR and MuSK autoantibodies in patients with MG, their clinical value in daily medical practice has not yet been established.

The fact that approximately 1 out of 3 individuals with SNMG were successfully identified as producers of these antibodies suggests that l-CBAs should be considered as a screening test when suspecting MG, as it could aid in decision making regarding a therapeutic approach with a timely instauration. These results further call for working on making l-CBAs widely available, as explained by Damato and the team.

“In clinical practice, the diagnosis of MG can be challenging in patients with negative results on AChR and MuSK antibody using standard assays, highlighting the need for a consensus on clinical and electrophysiological criteria for the diagnosis of SNMG and the importance of including CBAs in the diagnostic work-up of these patients,” the authors concluded. 

Reference

Damato V, Spagni G, Monte G, et al. Clinical value of cell-based assays in the characterisation of seronegative myasthenia gravis. J Neurol Neurosurg Psychiatry. Published online July 14, 2022. doi:10.1136/jnnp-2022- 329284