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Title: Limited costimulatory molecule expression on renal tubular epithelial cells impairs T cell activation. Author: Waeckerle-Men Y, Starke A, Wahl PR, Wüthrich RP. Journal: Kidney Blood Press Res; 2007; 30(6):421-9. PubMed ID: 17975322. Abstract: BACKGROUND/AIMS: MHC molecules are upregulated on renal proximal tubular epithelial cells (TEC) under inflammatory conditions. This allows TEC to act as 'non-professional' antigen-presenting cells (APC). The aim of this study was to compare the costimulatory molecule expression pattern and the T cell activation capacity between renal TEC and professional APC, e.g. bone marrow-derived dendritic cells (BM-DC). METHODS: Flow cytometry analysis was used to study the costimulatory molecule surface expression on TEC or BM-DC. Ovalbumin-specific CD4 and CD8 T cell activation induced by TEC or BM-DC was compared, in terms of T cell proliferation, cytokine production and CTL activity. RESULTS: TEC did not constitutively express significant amounts of costimulatory molecules. Stimulation of TEC with IFN-beta or IFN-gamma, but not other tested cytokines, enhanced the expression of PD-L1, ICOS-L and CD40. Compared to BM-DC, TEC only induced suboptimal T cell activation. Blockade of PD-L1 on both APC strongly increased T cell activity. Furthermore, high PD-L1-expressing TEC were more resistant to the cytolysis by CTL. CONCLUSION: The low costimulatory molecule expression may explain the suboptimal T cell activation by TEC. The IFN-upregulated negative costimulatory molecule PD-L1 on TEC may play a protective role to limit tissue injury during renal parenchymal immune responses.[Abstract] [Full Text] [Related] [New Search]