FIBRILLIN IMMUNOREACTIVITY IS ASSOCIATED WITH NORMAL OR FRAGMENTED ELASTIC MICROFIBRILS AT THE DERMAL-EPIDERMAL JUNCTION IN RECESSIVE DYSTROPHIC EPIDERMOLYSIS-BULLOSA

Elastic microfibrils containing fibrillin are a part of the fibroretic ular network of normal epidermal basement membrane. In dystrophic epid ermolysis bullosa (DEB) at least one other fibroreticular component, a nchoring fibrils, which contain type VII collagen, is known to be abno rmal. We therefore questioned whether elastic microfibrils and fibrill in expression might also be abnormal in DEB. By indirect immunofluores cence, and pre-embedding immunogold electron microscopy using a monocl onal antifibrillin antibody, we found no difference from control sampl es in either the quantity of the labelling or in the ultrastructural a ppearances of the immunolabelled fibrils in intact DEB skin. In areas of dermal-epidermal separation, however, we observed a number of thin, fragmented sublamina densa wisp-like structures, which still labelled for fibrillin despite lacking the typical ultrastructural features of normal elastic microfibril bundles. As a consequence of blistering in DEB, elastic microfibril bundles are disrupted, and fragmented microf ibrils may still remain attached to the blister roofs. Many of these e lastic microfibrils cannot be distinguished from rudimentary or altere d anchoring fibrils on morphology alone, and might therefore account f or misinterpretation of ultrastructural disorders of the dermal-epider mal junction. We postulate that, in intact skin, elastic microfibrils might contribute to dermal-epidermal adherence, in the absence of norm al-functioning anchoring fibrils.