Dynamic changes in cell-surface expression of mannose in the oral epithelium during the development of graft-versus-host disease of the oral mucosa in rats

BACKGROUND: The role of cell-surface glycoconjugates in oral mucosal graft-versus-host disease (GVHD) is still unclear, even though molecular changes in the oral epithelium are essential for the pathogenesis of these lesions. In this study, we investigated changes in the binding of mannose (Man)-specific Lens culinaris lectin (LCA) in the oral mucosa of rats with GVHD. METHODS: Lewis rat spleen cells were injected into (Lewis x Brown Norway) F(1) rats to induce systemic GVHD, including oral mucosal lesions. Tongue and spleen samples were evaluated using lectin histochemistry, immunohistochemistry, Western blotting, transwell migration assays and Stamper-Woodruff binding assays. RESULTS: Binding of Man-specific LCA expanded to the epithelial layers of the tongue in GVHD-rats. An expansion of LCA binding was related to the increased expression of mannosyltransferase in the oral mucosa. CD8(+) cells, effector cells of oral mucosal GVHD, expressed mannose-binding protein (MBP) and migrated to the medium containing Man in the transwell migration assay. Adherence of CD8(+) cells to the oral epithelium could be inhibited by pretreating CD8(+) cells with MBP antibody and/or by pretreating sections with Man-specific LCA. CONCLUSIONS: Increased expression of Man on keratinocytes leads to the migration and/or adhesion of CD8(+) cells in the surface epithelium, which is mediated in part by the MBP/Man-binding pathway during the development of oral mucosal GVHD.