CD274 and neoplasm: At αPD-L1CV, EVs #2 and #3 but not EV #1 increased αPD-L1-free PD-L1 on PC3 cells, and EV #3 had a stronger ability to dissociate αPD-L1 from tumor PD-L1, which was consistent with their ability to inhibit the αPD-L1-mediated rescue of CD8+ T-cell proliferation (Fig. 6a, b).