Autoantigens of cicatricial pemphigoid and their pathogenetic significance

Cicatrical pemphigoid (CP) comprises a group of patients with a chronic subepidermal blistering disease which primarily involves mucous membranes; lesions characteristically heal with scarring. Immunofluorescence investigations typically demonstrate deposits of tissue bound and circulating immunoreactants of the IgG and less frequently of the IgA class in a linear pattern along the basement membrane zone. These autoantibodies are thought to play an important role in the blister formation of CP. Most patients show binding to the bullous pemphigoid antigen 2 (BPag2), collagen type XVII, with a molecular-weight of 180 kD. A smaller group of patients with CP have autoantibodies to laminin 5. Animal models confirm that autoantibodies binding to these two adhesion molecules (BPag2 and laminin 5) are important in blister formation. There are other autoantigens described in CP; however, they are only found in small groups of CP patients and most of them are not further characterised. The described molecules are part of the hemidesmosomal adhesion complex. Impaired function of any component of this complex may lead to a separation of the epidermis from the dermis; better knowledge about the single molecules and the exact localisation of epitopes within these molecules may lead to further understanding of the clinical picture.