A novel MuSK cell-based myasthenia gravis diagnostic assay.

To improve the clinical diagnosis of neural autoimmune diseases, we developed an in-house muscle-specific kinase (MuSK) antibody cell-based assay (CBA) and compared its performance with RIA, ELISA, and other CBAs. Sera from patients with myasthenia gravis (MG) and other autoimmune diseases were analyzed. We found 46 (18.3%) MuSK-CBA Ab positive cases among 251 AChR-Ab negative cases [patients] and 4 (0.6%) MuSK-CBA Ab positive cases [among] the 624 AChR-Ab positive samples. Comparing these with available clinic assays, our highly specific CBA method is more sensitive than commercial ELISA and IFA(indirect immunofluorescence assay).