Intrinsic PD-L1 promotes antitumor activity of CD8^(+)cytotoxic T lymphocytes via in cis interaction with CD80

Dear Editor,Programmed cell death-ligand 1(PD-L1)on tumor cells can inhibit CD8+cytotoxic T lymphocyte(CTL)-mediated antitumor response by trans-engagement with programmed death protein 1(PD-1).Besides tumor cells,PD-L1 is expressed on T cells.However,the intrinsic role of PD-L1 in T cells has not been widely studied.PD-L1 expression is essential for the survival of activated CD8+T cells,and PD-L1 blockade at the contraction stage reduced the number of effector T cells[1].CD8+T cell responses to influenza virus infection were also impaired in PD-L1-deficient mice[2].