Immunoelectron microscopic examination of IgA deposition in dermatitis herpetiformis.

Ultrastructural localization of IgA in the skin of three Japanese patients with dermatitis herpetiformis (DH) was studied with the immunoelectron microscopic technique using periodate-lysine-paraformaldehyde fixation. In direct immunofluorescence studies, two of the three cases showed fine fibrillar deposition of IgA and the other case fine granules in the dermal papillae. In the former, the reaction products of IgA were present in the upper dermis forming various-sized aggregates which were occasionally arranged perpendicularly to the epidermis and appeared to be associated with microfibrillar bundles of the elastic tissue. Reaction products were also deposited to a lesser extent on the microfibrillar component of the elastic fibers at the lower part of the dermal papillae. However, in the latter, the reaction products were found to form smaller aggregates on and around the collagen fibrils rather than on the elastic tissue. Such a localization of IgA reaction products has not yet been reported in DH. The difference of the distribution patterns of IgA and the possible singularity of Japanese DH cases are discussed.