A child with antibodies targeting both linear IgA bullous dermatosis and bullous pemphigoid antigens.

BACKGROUND: Some patients with subepidermal blistering diseases show clinical, histologic, and immunopathologic features of both linear IgA bullous dermatosis and bullous pemphigoid. Such patients can be further characterized by defining the target of their circulating autoantibodies. We present the first case report of a child with linear deposits of IgA and IgG with circulating autoantibodies characteristic of both linear IgA bullous dermatosis and bullous pemphigoid.

OBSERVATIONS: Widely distributed subepidermal vesicles showing neutrophils in the dermal papillae developed in a 3-year-old boy. Direct immunofluorescence microscopy of perilesional skin revealed linear deposits of IgA, IgG, and C3 in the epidermal basement membrane. The patient responded to therapy with dapsone, and after 6 months, it was possible to discontinue treatment. Circulating IgA antibodies from this child bound the epidermal side of 1-mol/L saline-split skin and immunoblotted the 97-kd linear IgA bullous dermatosis antigen. Circulating IgG antibodies bound the epidermal and, at low titer, dermal sides of split skin. These IgG antibodies immunoblotted and immunoprecipitated bullous pemphigoid antigens 1 and 2.

CONCLUSIONS: Linear deposits of IgA and IgG in the epidermal basement membrane of patients with subepidermal bullous lesions may signify the coexistence of circulating autoantibodies directed against linear IgA bullous dermatosis and bullous pemphigoid antigens.