The start of an autoimmune disease: idiotypic network during early progression of myasthenia gravis.

Anti-acetylcholine-receptor antibodies of IgG and IgM classes and antiidiotypic antibodies were determined in patients with myasthenia gravis at various times after the start of the disease. Patients with a disease duration of less than one year had a higher prevalence of antiidiotypic antibodies (31/32) than patients who had had the disease for more than 5 years (49/79), and the concentration of antiidiotypic antibodies was also higher in patients with early disease (p less than 0.005). The concentrations of antiidiotypic antibodies decreased during progression of the disease concomittant with an increase in IgG anti-receptor antibodies. A change from IgM to IgG anti-receptor antibody production was also found. In two patients, who developed myasthenia after bone-marrow grafting and who were followed before start of disease, antiidiotypic antibodies appeared before anti-receptor antibodies and before symptoms of myasthenia were present. The high prevalence and concentration of antiidiotypic antibodies in early disease indicate that development and expression of antiidiotypic antibodies are important in early myasthenia gravis.