Epidermolysis bullosa acquisita associated with epidermal-binding circulating antibodies

Epidermolysis bullosa acquisita (EBA) is a rare, immunobullous disease, characterized by circulating and tissue-bound antibodies against type VII collagen (C7) of anchoring fibrils in the cutaneous basement membrane zone. These antibodies localize to the dermal aspect of salt-split skin on indirect and direct immunofluorescence (IMF). We report two patients with clinical features of EBA, in whom circulating IgG antibodies bound to the epidermal aspect of salt-split skin. In both patients direct IMF of salt-split perilesional skin revealed dermal IgG deposits, and direct immunogold immunoelectron microscopy showed antibody deposits in the region of anchoring fibrils. Their serum failed to react with epidermal or dermal extracts on Western immunoblotting. Epidermal-binding antibodies have not been reported previously in association with EBA, and the IMF findings in these cases suggest the development of autoantibodies to additional epidermal-associated antigens. Target antigen heterogeneity has been reported in most other immunobullous diseases, and may be a hitherto unrecognized feature of EBA.