LINEAR IGA BULLOUS DERMATOSIS - CHARACTERIZATION OF A SUBSET OF PATIENTS WITH CONCURRENT IGA AND IGG ANTIBASEMENT MEMBRANE AUTOANTIBODIES

Background and Design: The term linear IgA bullous dermatosis defines an immune-mediated blistering skin disease characterized by pruritic b listers, subepidermal separation with neutrophilic infiltration, and l inear IgA antibody deposition at the basement membrane zone (BMZ). How ever, some patients with linear IgA bullous dermatosis demonstrate bot h IgA and IgG anti-BMZ autoantibodies on immunofluorescence. We descri be four such patients and attempt to define this group of patients by studying their clinical, histopathologic, immunopathologic, immunoultr astructural, and immunochemical characteristics. Results: Clinically, all four patients had a generalized pruritic blistering skin disease c onsistent with linear IgA bullous dermatosis. Histopathologically, all four cases demonstrated subepidermal blister formation with a predomi nantly neutrophilic dermal infiltrate. Immunopathologically, tissue-bo und IgA (in four of four patients) and IgG (in three of four patients) antibodies were detected at the BMZ. Circulating IgA (in four of four patients) and IgG (in four of four patients) labeled the epidermal BM Z of normal human skin fractured at the lamina lucida and did not labe l the dermal BMZ. By immunoblot analyses, IgA (in three of three patie nts) and IgG (in one of three patients) circulating antibodies labeled the 97-kd linear IgA bullous dermatosis antigen. By direct immunoelec tron microscopy, IgA and IgG antibodies were localized (in two of two patients) exclusively within the upper lamina lucida of the BMZ. Concl usions: Four cases of an immune-mediated blistering skin disease typic al for linear IgA bullous dermatosis demonstrated both IgA and IgG ant i-BMZ autoantibodies against the linear IgA bullous dermatosis antigen within the upper lamina lucida. We conclude that linear IgA bullous d ermatosis should include a subgroup of patients with both IgA and IgG anti-BMZ autoantibodies.