EXPRESSION OF TENASCIN IN THYMUS AND THYMIC NONLYMPHOID CELLS

Tenascin (TN) is an extracellular matrix glycoprotein that is widely e xpressed in fetal tissues and tumor matrices but is absent from most n ormal adult tissues. It is transiently expressed at sites of wound hea ling and has been shown to inhibit some types of T cell activation. We have examined the expression of TN in rat and human thymic tissue. Ou r results indicate that TN is expressed in both neonatal and adult rat thymus, and that in human thymus TN is present in a meshlike network at the corticomedullary junction. In addition, cultured human thymic n on-lymphoid cells grown in serum-containing medium synthesize TN, wher eas under serum-free conditions these cells secrete TN in response to transforming growth factor-beta.