DIFFERENTIAL EXPRESSION OF TENASCIN IN THE SKIN DURING HAPTEN-INDUCEDDERMATITIS

Tenascin is a large extracellular matrix glycoprotein which is found i n limited regions of normal adult tissues including the skin. We inves tigated the induction of tenascin expression in mouse skin during hapt en-induced dermatitis. In the dorsal skin, hapten application first in duced a transient expression of tenascin in deeper regions of the skin . Its distribution then spread over the whole dermis corresponding to the infiltration of Mac-2-positive macrophages. In the ear, tenascin w as consistently found in the subcutaneous tissue on the inner side, bu t very little was seen on the outer side. Tenascin did appear transien tly, however, on both sides under hapten treatment. In the early phase of allergic contact dermatitis, no apparent induction of tenascin exp ression was observed in the swollen ear. However, there was an abundan t tenascin expression on both sides during healing. Tenascin expressed under normal conditions was mostly the 180-kDa isoform, while the 230 -kDa isoform was markedly induced during healing of the dermatitis. Th ese results suggest that tenascin, particularly the larger 230-kDa iso form, may play important roles in the pathogenesis and healing of hapt en-induced dermatitis.