Immunosuppressants increase the levels of natural autoantibodies reactive with glycosaminoglycans in myasthenia gravis

• Carbohydrate-reactive antibodies are investigated in sera of myasthenia patients.
• Αnti-α-mannose IgG level is increased in anti-AChR-positive myasthenia patients.
• Anti-chondroitin-sulphate C IgG levels are increased in patients with myasthenia.
• Immunosuppressants increase levels of anti-glycosaminoglycan IgM natural antibodies.

Increasing number of evidences support the role of glycosylation in the evolution of autoimmunity. We examined carbohydrate-reactive natural autoantibodies systematically for the first time in patients with autoimmune myasthenia gravis.Antibodies reactive to glycosaminoglycans were measured with CovaLink ELISA in the sera of 59 myasthenia patients as well as in 54 healthy controls. We used the GlycoChip carbohydrate array to characterize individual carbohydrate recognition patterns.Chondroitin-sulphate C and anti-α-mannose-specific IgG levels were significantly elevated in myasthenia patients. Unexpectedly, we found that immunosuppressants increased the levels of the protective IgM glycosaminoglycan-reactive natural antibodies demonstrating a new role for these agents in immunoregulation.