Dermatitis herpetiformis with linear IgA deposition: ultrastructural localization of in vivo bound IgA.

Ultrastructural localization of bound IgA in the skin of a patient suffering from dermatitis herpetiformis with linear IgA deposition at the dermo-epidermal junction was studied using the horseradish peroxidase labelled antibody method. The reaction products were observed as electron-dense materials, not only immediately below the cytomembrane of the basal cells but also in the uppermost dermis just below the basal lamina. The major portion of the lamina lucida was free of the reaction products. These findings suggest a diversity in the mode of IgA deposition and the possibility of the presence of different antigens in the basement membrane zone, to which IgA class antibodies may be bound respectively.