Immunoelectronmicroscopic localization of IgA in skin of patients with dermatitis herpetiformis.

Ultrastructural localization of in vivo-bound IgA in the skin of patients with dermatitis herpetiformis was determined by using a modified peroxidase-antiperoxidase multistep method. Three types of reaction product deposition are seen. The most common type of reaction product deposition, that which is identified by direct immunofluorescence as the speckled type of IgA deposit, shows up as clumps and yarnlike fibrils. The second type of IgA deposition, which is a linear band by direct immunofluorescence, appears to be associated with anchoring fibrils. The third of IgA deposition, which is also linear by immunofluorescence, is confined to the lamina lucida.