Immunoglobulins are deposited at the dermoepidermal junction in several diseases including bullous pemphigoid, lupus erythematosus, acquired epidermolysis bullosa (AEB), and dermatitis herpetiformis (DH). In some of these diseases (eg, bullous pemphigoid and AEB), the immunoglobulin is readily detected in the serum and has been used to precisely identify and characterize its complementary antigen in the skin. In DH, although granular IgA deposits are usually known to occur in the papillary dermis in microfibrillary bundles beneath the basement membrane of uninvolved skin, especially near lesions, the existence of a particular antigen or the nature of the deposition is still unknown.
Egelrud and Bäck1 have directly attacked this problem by solubilizing the immunoglobulins. They react 4-mm punch biopsy specimens of clinically normal skin from patients with DH with radioactive sodium iodide. The radioactively labeled proteins were solubilized with sodium dodecyl sulfate or by cleaving the IgA using pepsin. Pepsin cleaves all
Lowell A. Goldsmith. Immunoglobulin Disposition in the Skin. Arch Dermatol. 1986;122(1):97–98. doi:10.1001/archderm.1986.01660130101036