Pathogenetic studies in bullous pemphigoid--review of the literature and our own results.

Abstract

ABSTRACTBullous pemphigoid (bP) is a blister‐forming disease, probably of autoimmune nature. Its genetic background has not been established yet. Associations with other autoimmune diseases and, to some extend, with malignant tumors are noteworthy. The blisters are located subepidermally in the lamina lucida between the cytoplasmic membrane of the basal cells and the lamina densa of the basement membrane. The bP antigen, which is produced by basal cells, serves as an attachment factor and can be liberated into the blister fluid, probably by serine proteases from leucocytes. The formation of antigen‐antibody complexes is favoured afterwards. Freely circulating bP antibodies, mostly of the IgG class, are fixed in the skin tissue in vivo and in vitro and bind complement. Components of the classical complement pathway as well as of the amplification loop are activated locally in the skin tissue and fixed. The content of immune complexes is increased in the serum and in the blister fluid. They partially consist of specific bP antigen‐antibody complexes. The determination of the entire bP antibody titer (after immune complex splitting) correlates well with the clinical course of the disease.Chemotactic factors for neutrophils and eosinophils are released into the blister fluid after complement activation, so that leucocyte attraction is mediated. Deviations of humoral and cellular immune reactivity have not been studied sufficiently. There might be an immune modulating effect of immune complexes and other serum factors on T‐lymphocytes due to steric hindrance of surface receptors. In vivo and in vitro models in rabbit cornea, skin explants, and frozen sectioned skin tissue suggest that the interaction of circulating bP antibodies with the bP antigen followed by complement activation and attraction of neutrophils might be the primary immunopathological mechanism, producing an immune complex mediated inflammation.