Reduced tumor-antigen density leads to PD-1/PD-L1 mediated impairment of partially exhausted CD8(+) T cells

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Item Type:	Article
Title:	Reduced tumor-antigen density leads to PD-1/PD-L1 mediated impairment of partially exhausted CD8(+) T cells
Creators Name:	Kaiser, A.D., Schuster, K., Gadiot, J., Borkner, L., Daebritz, H., Schmitt, C., Andreesen, R. and Blank, C.
Abstract:	Clinical progression of cancer patients is often observed despite the presence of tumor-reactive T cells. Co-inhibitory ligands of the B7 superfamily have been postulated to play a part in this tumor immune escape. One of these molecules, PD-L1 (B7-H1, CD274), is widely expressed on tumor cells and has been shown to mediate T-cell inhibition. However, attempts to correlate PD-L1 tumor expression with negative prognosis have been conflicting. To better understand when PD-1/PD-L1 mediated inhibition contributes to the functional impairment of tumor-specific CD8(+) T cells, we varied the levels of antigen density and/or PD-L1 expression at the surface of tumor cells and exposed them to CD8(+) T cells at different levels of functional exhaustion. We found that the gradual reduction of cognate antigen expression by PD-L1-expressing tumor cells increased the susceptibility of partially exhausted T cells to PD-1/PD-L1 mediated inhibition in vitro as well as in vivo. In conclusion, chronically stimulated CD8(+) T cells become sensitive to PD-1/PD-L1 mediated functional inhibition upon low antigen detection; a setting which is likely involved during tumor immune escape.
Keywords:	PD-1, PD-L1, T-Cells, Tumor Microenvironment, Animals, Mice
Source:	European Journal of Immunology
ISSN:	0014-2980
Publisher:	Wiley
Volume:	42
Number:	3
Page Range:	662-671
Date:	March 2012
Official Publication:	https://doi.org/10.1002/eji.201141931
PubMed:	View item in PubMed

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