A potential role for B-cell activating factor in the pathogenesis of autoimmune myasthenia gravis

Objective: To compare serum B-cell activating factor (BAFF) levels in patients with myasthenia gravis (MG) with those in control subjects without MG. Design: Case-control study. Subjects: Forty-three patients with MG were compared with control subjects without MG. These included 48 healthy subjects, 25 patients with multiple sclerosis, and 3 patients with amyotrophic lateral sclerosis. Results: In all subjects studied, there was no correlation between the serum BAFF level and the concentration of total IgG, IgA, or IgM. The BAFF levels in patients with multiple sclerosis or amyotrophic lateral sclerosis were not significantly different from those in healthy subjects. However, BAFF levels in patients with MG were significantly higher than those of all the control subjects. There was no correlation or dependence between the serum BAFF level and the extent or severity of disease. There was a trend for BAFF levels to be higher in patients who were seropositive for acetylcholine receptor-specific antibodies. Conclusions: We report that BAFF levels are increased in patients with autoimmune MG. Our data suggest that BAFF is likely to play a role in the pathogenesis of MG by promoting the survival and maturation of autoreactive B cells.