CD274 and cancer: Exosomes derived from BC cells suppressed T cells proliferation through TGF-β, which inhibited immune response.126 A recent study demonstrated that human melanoma-secreted exosomes carried immunosuppressive programmed cell death ligand 1 (PD-L1), inhibited the function of CD8 T cells, and exacerbated tumor growth.127 Meanwhile, exosomes released by cancer cells also promote the mediation and persistence of inflammation.