PDCD1 and neoplasm: To test which T-cell populations are essential, we either utilized FTY720 to block peripheral lymphocytes from trafficking into tumor tissues or used an anti-CD8 antibody to deplete CD8+ T. Here, we found that combination therapy of IFNα and PD-1 blockade controlled the FTY720 administrated tumor similarly to that of the control group, while local depletion of CD8+ T cells diminished all the antitumor effects (Fig. 6g).