Equine bullous pemphigoid IgG autoantibodies target linear epitopes in theNC16A ectodomain of collagen XVII (BP180, BPAG2)

Bullous pemphigoid (BP) is an autoimmune subepithelial blistering dermatosi s of humans, dogs, cats and pigs. It is characterized by skin-fixed and cir culating IgG autoantibodies that target one or both BP antigens. An immunol ogical homologue of BP in humans was diagnosed in two horses with cutaneous and mucosal ulcerations as well as microscopic subepithelial vesiculation Immunological investigations revealed similar findings for both the horses. Direct immunofluorescence demonstrated the presence of IgG deposited linea rly at the dermoepidermal junction in mucosal and skin biopsy specimens. In direct immunofluorescence testing confirmed the existence of circulating ba sement membrane-specific IgG autoantibodies. Using intact and salt-split ep ithelial substrates, serum IgG were shown to target antigens situated not o nly at the basal, but also at the lateral and apical aspects of stratum bas ale keratinocytes. Immunoblotting and ELISA corroborated that the IgG from affected horses, but not those from normal controls, exhibited high immunor eactivity against the NC16A extracellular domain of type XVII collagen (BPA G2, BP180). Equine BP could be proposed, therefore, as another spontaneous model of this most common basement membrane autoimmune dermatosis of humans . (C) 2000 Elsevier Science B.V. All rights reserved.