Pemphigoid gestationis.

Abstract

ORIGINAL ARTICLE, p 120 Pemphigoid gestationis (PG) is a rare and self‐limiting immunobullous disorder of pregnancy, the exact pathogenesis of which has not been fully characterized. It is believed to result from a breakdown of the immunological tolerance of the mother to the fetoplacental unit resulting in autoantibodies to the main target antigen collagen XVII (BP180), which is presented to the maternal immune system by aberrantly expressed human leucocyte antigen (HLA) class II molecules in the placenta. Recent studies have demonstrated that these antibodies are mostly of the IgG4 subclass,1 unlike previous data supporting the role of IgG1 and IgG3 antibodies.2 These antibodies cross the placenta and cross‐react with collagen XVII in the maternal skin resulting in formation of immune complexes, activation of complement and inflammatory cell recruitment, with the release of inflammatory mediators resulting in blister formation on maternal skin. In most patients, antibodies target the extracellular noncollagenous (NC) 16A domain of BP180 antigen; however, in one study, the sera of nine of 15 patients with PG reacted with at least one additional antigenic site other than NC16A.3 In another study, about 10% of patients additionally showed antibodies to BP230 antigen, possibly due to the phenomenon of epitope spreading.4