Dual Control of Antitumor CD8 T Cells through the Programmed Death-1/Programmed Death-Ligand 1 Pathway and Immunosuppressive CD4 T Cells: Regulation and Counterregulation

作者：Currie Andrew J; Prosser Amy; McDonnell Alison; Cleaver Amanda L; Robinson Bruce W S; Freeman Gordon J; van der Most Robbert G^*

来源：The Journal of Immunology, 2009, 183(12): 7898-7908.

DOI：10.4049/jimmunol.0901060

Tumors have evolved multiple mechanisms to evade immune destruction. One of these is expression of T cell inhibitory ligands such as programmed death-ligand 1 (PD-L1; B7-H1). In this study, we show that PD-L1 is highly expressed on mesothelioma tumor cells and within the tumor stroma. However, PD-L1 blockade only marginally affected tumor growth and was associated with the emergence of activated programmed death-1(+) ICOS(+) CD4 T cells in tumor-draining lymph nodes, whereas few activated CD8 T cells were present. Full activation of antitumor CD8 T cells, characterized as programmed death-1(+) ICOS(+) Ki-67(+) and displaying CTL activity, was only observed when CD4 T cells were depleted, suggesting that a population of suppressive CD4 T cells exists. ICOS(+) foxp3(+) regulatory T cells were found to be regulated through PD-L1, identifying one potentially suppressive CD4 T cell population. Thus, PD-L1 blockade activates antitumor CD8 T cell most potently in the absence of CD4 T cells. These findings have implications for the development of PD-L1-based therapies. The Journal of Immunology, 2009, 183: 7898-7908.

• 出版日期2009-12-15