Heavy and light chain isotypes of immunoglobulin in epidermolysis bullosa acquisita.

Epidermolysis bullosa acquisita (EBA) is a chronic acquired blistering disease with characteristic clinical, pathologic, and immunopathologic features. The disease is characterized immunopathologically by circulating and tissue-bound IgG class autoantibodies (EBA antibodies) to the basement membrane zone of stratified squamous epithelium. Previous studies have shown that circulating and tissue-bound EBA antibodies are heterogenous in their ability to activate complement and have raised the possibility that functional heterogeneity might be related to IgG subclass restriction. In this study, we have characterized the IgG subclasses of the circulating and tissue-bound EBA antibodies by immunofluorescence and have examined the relationship between IgG subclass and complement binding. The results show that EBA antibodies belonging to all IgG subclasses are present in the skin of EBA patients. The results also show that EBA antibodies belonging to all IgG subclasses are present in the sera of most patients, including sera with and without complement binding EBA antibodies.