Evaluation of serum IgG subclass concentrations in myasthenia gravis patients

Myasthenia gravis (MG) is an autoimmune disease characterized by preferential production of a variety of autoantibodies. We aimed to investigate serum IgG subclass levels in MG patients. Serum IgG subclass levels from 85 MG patients were determined by the immunonephelometric assay. The median levels of IgG1, IgG2, IgG3, and IgG4 in MG patients were 7,360 mg/L, 5,750 mg/L, 860 mg/L, and 340 mg/L, respectively. When compared with normal controls, a significant increase of IgG1 (p = .000), IgG2 (p = .000), IgG3 (p = .000), and IgG4 (p = .029) was observed in MG patients. When the MG patients were divided into different groups, higher levels of IgG1 and IgG3 were observed in anti-AChR antibody positive group. Also, the level of IgG1 was statistically higher in female than that in male, and the level of IgG4 in late-onset group was significantly higher than that in early-onset group. There was a significant inverse correlation between the concentrations of IgG2 and IgG4 and disease duration. Our data suggested that IgG subclasses were preferentially produced during the process of MG, which could enable us a better understanding of MG.