大疱性类天疱疮自身反应性IgG抗体亚型研究进展

大疱性类天疱疮（BP）是一种自身免疫性表皮下大疱性皮肤病，以c3和（或）IgG在基底膜带线状沉积为特征。研究提示，抗BP180IgG抗体通过激活补体，可能是诱发大疱形成的主要原因，而自身抗体结合的抗原表位多数包括BP180NC16A结构域。由于不同IgG抗体亚型含量以及激活补体的能力不同，其致病性也不同。免疫荧光和酶联免疫吸附试验提示，IgG1和IgG4为主要的自身反应抗体亚型。体外实验和动物模型均证实，IgG1为主要的致病抗体，其含量与BP的严重程度平行；IgG4具有较弱的活化炎症细胞的致病作用和封闭抗原表位的保护作用。最近的研究提示，抗BP180IgG抗体可以不依赖激活补体和炎症细胞这两种方式诱导表皮真皮分离。因而关于各IgG亚型的致病能力，特别是IgG4的作用现在仍然不清楚。

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 BP18ONC16A 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 immunosorhent assay have confirmed that IgG1 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 pathoenesis of BP.