Abundance of interstitial heparan sulfate in granuloma annulare but not in other mucinous skin diseases

BACKGROUND: Heparan sulfate (HS), unlike other glycosaminoglycans, is mainly located on cell surfaces but can be shed into the interstitium by a regulated process. It has been found in interstitial fluid drained from cutaneous wounds, but otherwise the conditions under which the release of HS from the cell surface occurs are unknown. To better characterize this process, we have investigated the presence of interstitial HS in various skin diseases with glycosaminoglycan accumulation. METHODS: Histologic routine material was stained immunohistochemically using an antibody recognizing HS. RESULTS: Heparan sulfate immunoreactivity is present in the interstitium of young cutaneous scars and in the interstitium of the inflammatory infiltrate of granuloma annulare. No reactivity was found in a number of non-inflammatory skin diseases with mucin deposition. CONCLUSIONS: The selective presence of interstitial HS in only two of the investigated skin conditions supports the existence of a regulated mechanism to release HS from the surface of cells into the interstitium. It is suggested that HS modulates the biologic actions of growth factors and cytokines not only during wound repair but possibly also in inflammatory skin diseases such as granuloma annulare.