Background:  Myasthenia gravis (MG) is an autoimmune disease caused by serum auto-antibodies (autoAbs) against components of the muscle membrane at the neuromuscular junction (NMJ). Most cases of MG (80 to 85%) involve autoAbs directed against acetylcholine receptor (AChR) but a minority of patients (15 to 20%) instead reveals autoAbs directed against other components of the NMJ.
Our aim in this study is to establish a functional and reliable anti-MuSK CBA  and to screen a set of Algerian MG samples with this assay and try to detect anti-MuSK antibodies
Patients and methods : A set of  20 of the patients’ sera were selected to be tested with a CBA for MuSK (MuSK-CBA, mean age: 29.47 years). All sera have been first assayed by  radioimmunopreciitation assay (RIPA) for the detection of  anti-AChR and anti-MuSK antibodies. 06 samples were anti-AChR seropositive while the remaining 14 sera were anti-AChR  seronegative. All  sera have been seronegative for anti-MuSK by RIPA.
Results: None of the 20 patients” sample s micrographs were scores higher than the negative controls which translates to the absence of anti-MuSK antibodies in every serum. They scored the anti-MuSK positive-control sera images an average of 98.60 ± 1.21% (mean ± SD range= 91-100%, where 100% means unequivocally positive; n=4 scorers).
Conclusion: The Cell-based for anti-MuSK detection was able to clearly distinguish RIPA-positive and RIPA-negative control samples. Despite its proven robustness by others groups, our CBA did not detect anti-MuSK antibodies in any of our MG patients’ sera.
Key words: Myasthenia gravis (MG), anti-MuSK, autoimmune disease