Detection of autoantibody against 97-kD antigen by immunoblot, but not by indirect immunofluorescence, in a patient with linear IgA bullous dermatosis.

A case of linear IgA bullous dermatosis in an 85-year-old man is reported. Direct immunofluorescence (IF) of the lesional skin showed linear deposition of IgA and weak deposition of IgG at the basement membrane zone. Although no circulating autoantibody was detected by indirect IF, immunoblotting analysis using NaCl-separated normal human epidermal extracts revealed a circulating IgA antibody which bound to the 97-kD antigen.