IgA immunoreactive deposits collocal with fibrillin immunoreactive fibers in dermatitis herpetiformis skin

The IgA immunoreactive granules or fibrils, characteristically found in dermal papillae of patients with dermatitis herpetiformis, were previously reported to be associated with microfibrillar bundles. Recently, fibrillin, a component of such 8-12 nm microfibrils, was identified. In normal skin, the fibrillin immunoreactive microfibrils are present at the periphery of elastic fibers and are also present without concomitant amorphous elastin in the dermal papillae close to the lamina densa. The localization of the IgA immunoreactive material in the dermal papillae of 17 patients with dermatitis herpetiformis was compared with the distribution of the fibrillin immunoreactive fiber network. Immunofluorescence methods using FITC- and TRITC-labelled antibodies, an avidin-biotin-peroxidase complex technique, and standard elastin staining procedures, were used in several sequential and double staining procedures. In 13 specimens, in which the IgA reactivity was granular, most of the granules were located at the sites of fibrillin-reactive structures. As it could not be excluded that the collocality was coincidental, it could not be ascertained whether the IgA granules were in fact related to the fibrillin immunoreactive fibers in these specimens. However, in 4 specimens with both granular and fibrillar IgA immunoreactive deposits, these were clearly related to and located at the sites of fibrillin-reactive fibrils in the dermal papillae. The results confirm earlier reports of an association of IgA reactive deposits with microfibrillar bundles in dermatitis herpetiformis skin, though the possibility of their binding to other extracellular matrix component(s) has not been ruled out. The findings suggest that fibrillin may be the structural component (or one of them) to which IgA reactive deposits bind in the skin of patients with dermatitis herpetiformis.