[Thy-1 induction and its tissue-specific regulation in the rat--studies on acute rejection and granulomatous inflammation].

Thy-1 is a surface molecule known to be involved in cellular adhesion and signal transduction, and it has been found that Thy-1 induced on endothelial cells regulates vascular permeability both in vitro and in vivo at sites of inflammation. To further investigate regulation of Thy-1 expression at inflammatory sites, we made two in vivo models using LEJ/Hkm, rat strain. One is allogenic transplantation model and another is granulomatous inflammation model induced by Freund's complete adjuvant. Thy-1 mRNA was detected in the normal brain, thymus, heart, lung, liver, kidney, skin and lymph node but not in peripheral blood mononuclear cells by reverse transcription and polymerase chain reaction method. In the skin transplantation and dermal inflammation, Thy-1 expression was up-regulated on endothelial cells. On the other hand, Thy-1 was induced on rat renal tubular epithelial cells in acute cellular rejection. No obvious Thy-1 upregulation was observed in the granulomatous inflammation in the kidney. Moreover, no induction of Thy-1 expression was seen in either acute cellular rejection or granulomatous inflammation in the lung. These observations suggested that there is a tissue-specific regulation on Thy-1 expression and that Thy-1 induction appears to be one of important factors that modulates acute cellular rejection of skin allografts through its function on vascular permeability regulation.