We studied the longitudinal relation between disease severity and titers of antigen-specific
IgG subclasses in sera of patients with myasthenia gravis and antibodies to Muscle Specific
Kinase (MuSK MG). Six patients were included of whom 55 samples had been collected
during 2.5–13.4 years. Anti-MuSK antibodies were determined by ELISA and with a cell-
based immunofluorescence assay. Disease severity was scored on a semi continuous
scale. Only antigen-specific IgG4, and not IgG1, titers were significantly associated with …