A new test offers a rapid, sensitive and inexpensive way to detect anti-acetylcholine receptor (AChR) antibodies in patients with myasthenia gravis (MG).
The study with that finding, “A Simple, Rapid and Non-Radiolabeled Immune Assay to Detect Anti-AChR Antibodies in Myasthenia Gravis,” was published in the journal Laboratory Medicine.
Approximately 75% to 95% of patients with MG have anti-AChR antibodies in their blood, which target AChRs in the neuromuscular junction — the site where nerve cells and muscle connect — leading to symptoms such as fatigue and weakness in the skeletal muscles. Anti-AChR antibodies may be classified as binding, blocking or modulating according to their action.
The available techniques to detect anti-AChR antibodies in MG patients present complications such as using radioactive materials not allowed in all laboratories, or being technically challenging. As such, having a simpler, rapid, nonradioactive and sensitive test would be beneficial, the researchers from the National Institute of Mental Health and Neurosciences, in India, considered.
The team evaluated the dot blot assay, which detects, analyzes and identifies proteins on a paper membrane, comparing it to a technique called ELISA (both a commercial and their own version) as a way to bind anti-AChR antibodies and diagnose MG.
For this purpose, the scientists collected sera from patients with MG, patients without MG (but who had conditions such as multiple sclerosis, epilepsy, connective-tissue disease, and motor neuron disorders), and healthy controls, 85 each. MG patients were categorized into ocular MG (OMG, 34 patients) and generalized MG (GMG, 51 individuals).
The results revealed that the dot blot test and both the in-house and commercial ELISA assays detected anti-AChR antibodies in 65 MG patients (76.5%). Specifically, the three assays found the targeted antibodies in 47 GMG patients (92.2%) and 18 individuals with OMG (52.9%). This finding “is in line with other reports demonstrating the low prevalence of anti-AChR antibodies in OMG, compared with GMG,” the researchers wrote.
All three tests did not detect anti-AChR antibodies in the healthy controls and in the non-MG patients. The dot blot test and the in-house ELISA assay showed similar diagnostic ability to detect anti-AChR antibodies. Also, the findings revealed the sensitivity and specificity of the in-house ELISA was 100% comparable to those of the commercial assay.
Overall, the study showed that “the dot-blot assay is a rapid, simple, sensitive tool for the serological testing of patients with clinical suspicion of or confirmed MG,” the team wrote. “It will be useful in resource-limited laboratories because it offers less financial and technical burden, compared with other methods,” they added.