Immunoglobulin G subclasses of autoreactive antibodies in bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune subepidermal bullous disorder characterized by linear deposition of immunoglobulin G (IgG) and/or C3 along the basement membrane zone.It is supposed that anti-BP180 IgG antibodies play a major role in bulla formation via activation of complement.The BP180NC16A domain has been observed in the majority of antigenic epitopes binding to autoantibodies in BP.The differences in both serum concentrations and the ability to activate complement proteins contribute to the variety in the pathogenicity of different IgG subclasses of autoantibodies.Both immunofluorescence assay and enzyme-linked immunosorbent assay have comfirmed that lgGl and IgG4 are the predominant IgG subclasses of anti-BP180 autoantibodies.Furthermore,in vitro experiment and animal experiment have demonstrated that IgG1 autoantibodies are the primary pathogenic autoantibody,and their serum levels are correlated with disease severity.By contrast,IgG4 may play a weak pathogenic role by slightly activating leucocytes as well as a protective role by blocking the epitopes of pathogenic autoantigens in BP.Latest studies have revealed that anti-BP180 autoantibodies may induce the separation of dermis and epidermis independent of the activation of complement proteins as well as inflammatory cells.The real function of different IgG subclasses of autoantibodies,especially the IgG4 subclass,remains unclear in the pathogenesis of BP. Key words: Pemphigoid, bullous;  Immunoglobulin G;  Autoantibodies