Tenascin (TN) is one of the astroglia-derived extracellular matrix proteins, expressed in radial glia and immature astroglia in the developing mouse brain. TN can be detected only very low levels in adult mouse brain, however, is highly up-regulated in sites of injured central nervous system (CNS) depending on the proliferation of reactive astrocytes with GFAP expression. To investigate the role of tenascin-expressing astrocytes played in the injured brain, we analyzed TN knockout (TN/KO) mouse. We have previously reported that TN is one of the essential molecules for proliferation of the primary culture of astrocytes, and from our injured mouse brain model with stab wound, GFAP expression in the lesion sites was down regulated sharply at earlier stage of after the lesion in TN/KO mouse than the WT mouse (SFN 2004). Some of the inflammatory cytokines are expressed not only in lymphocytes but also in injured spinal cord, and also those receptors are expressed in cultured astrocytes. To evaluate immune respo...