[The Mechanism of HLA Class I and PD-L1 Expression of Cancer Cells in Tumor Microenvironment].

ABSTRACT

HLA class I and PD-L1expressed on cancer cells play a pivotal role in the CTL recognition mechanism against cancer cells in the tumor microenvironment. It is well known that IFN-g upregulates PD-L1as well as HLA class I expression in cancer cells, and it is suggested that TILs, including CTL, produce IFN-g in the tumor microenvironment. Therefore, there is a possibility that IFN-g produced by activated TILs upregulate both HLA class I and PD-L1expression in cancer cells in the tumor microenvironment. We propose that the anti-tumor effect of CTL could be enhanced if the inhibition of CTL recognition mechanism against cancer cells via the PD-1/PD-L1pathway is canceled by anti-PD-1or anti-PD-L1antibody.