CD274 and neoplasm: ICAM-1-LFA-1 binding between tumour-cell-derived exosomes and leukocytes can interfere with leukocyte adhesion to activated endothelial cells and their recruitment to tumours [96] but also with the activation of cytotoxic CD8+ T cells [97], whose interaction with IFN-γ-induced exosomes containing the checkpoint molecule PD-L1 seems to be one of the numerous mechanisms for immune evasion by cancer cells.