PDCD1 and neoplasm: Tumor EVs surface PD-L1 can bind to CD8+ T cell surface programmed cell death protein 1 (PD-1), inhibiting CD8+ T cell activation and proliferation; surface ICAM-1 can interact with T cell surface LFA-1, promoting EVs PD-L1 mediated immune suppression; tumor EVs can also induce immune cell apoptosis or differentiation into immunosuppressive cells (77, 78).