Catabolism of pemphigus foliaceus autoantibodies by high-dose IVIg therapy.

High-dose intravenous immunoglobulin (HD-IVIg) has several distinguishing therapeutic characteristics. However, a certain number of pemphigus cases have been experienced, which did not respond to HD-IVIg. This is the first case report that the serum level of anti-desmoglein (Dsg) 1 antibody rebounded, critically associated with IgG serum level. We describe a patient with pemphigus foliaceus (PF), unresponsive to oral prednisolone followed by pulse therapy and double-filtration plasmapheresis, in whom clinical remission was induced by 4 courses of HD-IVIg. Anti-Dsg1 antibody levels, serum IgG and disease activity were monitored. Anti-Dsg1 antibody titers rapidly decreased after IVIg treatment when total IgG levels were high; however, the serum level of anti-Dsg1 antibody rebounded as the total IgG level returned to normal. The levels of anti-Dsg1 antibody were decreased for an average of 13.7 days after treatment. The therapeutic effect of IVIg treatment was associated with an increased serum level of total IgG. IVIg therapy reduced the titers of autoantibody by accelerating the catabolism of immunoglobulin induced by high IgG serum levels. IVIg itself appears to accelerate IgG degradation rather than suppress IgG production. Sufficient suppression of antibody production is critical for successful treatment with IVIg.