Programmed cell death-Ligand 1(PD-L1), identified on the membrane of exosomes derived from melanoma, binds to programmed cell death protein 1(PD-1) on the surface of CD8 (+) T cells, which will cause temporary blockade of CD8 (+) T cells immunity, rather than permanent suppression [85, 86]. Here, PDCD1 is linked to melanoma.