Pemphigoid (herpes) gestationis: Neue aspekte zur pathogenese und diagnostik

Pemphigoid gestationis (PG) is an autoimmune subepidermal blistering disease associated with pregnancy. Patients can present with blisters or with itchy macular, papular, urticarial or eczematous lesions. Direct immunofluorescence microscopy of perilesional skin biopsies shows linear deposits of C3 along the basement membrane. Recent biochemical and molecular biologic studies have shed light on the pathogenesis of PG. Antibodies are directed against the 180-kDa bullous pemphigoid antigen (BP180), also referred to as type XVII collagen. BP180 is an important component of epidermal hemidesmosomes, epithelial structures essential for adhesion of basal keratinocytes to the cutaneous basement membrane. Circulating anti-BP180 autoantibodies predominantly belong to the lgG1 and lgG3 subclasses. Binding of the antibodies leads to complement activation, infiltration of inflammatory cells into the skin, and, finally, to subepidermal blister formation. These autoantibodies can be demonstrated by immunoblotting and ELISA techniques using recombinant BP180 as the target antigen. Both tests are sensitive and specific and in most cases make it easier to distinguish between PG and other pregnancy-associated skin diseases without resorting to skin biopsy.