An acquired bullous dermatosis due to an autoimmune reaction against uncein

A 59-year-old male showed acquired, mechanically induced, scarring blisters on the fingers, toes, scalp and abdomen, as well as in the oral cavity. Ultrastructural and immunohistochemical examination of the bullae revealed junctional epidermal-dermal separation and IgG deposits in the lamina lucida of the basement membrane zone (BMZ), where the reactivity of the 19-DEJ-1 monoclonal antibody was decreased. Anti-BMZ autoantibodies detected in his serum were reactive to the lower lamina lucida region of normal human skin. SDS-PAGE of affinity purified antigens from human keratinocytes with IgG from the patient's serum revealed three polypeptide bands at 165, 135 and 100 kDa, in reduced condition. The indirect immunofluorescence test of his serum was negative on skin cryosections from patients with lethal junctional epidermolysis bullosa. Pretreatment of normal human skin sections with the patient's serum, blocked the binding of 19-DEJ-1 monoclonal antibody but not that of the GB3 monoclonal antibody. This case is considered to be an acquired autoimmune bullous dermatosis due to an autoantibody reaction against uncein (19-DEJ-1 antigen), a component of anchoring filaments.