CD274 and neoplasm: In OSCC, we find that the content of cytotoxic T cells at the lymph node metastatic site is significantly higher than that at the primary site, which may be due to the decrease in M2 macrophages at the metastatic site, the weakening of cytotoxic T cells depletion mediated by PD-L1 expressed in OSCC cells, and the increased immunogenicity of tumor cells.