CD274 and Autoimmunity: Immune hot tumors are characterized by elevated levels of programmed death ligand‐1 (PD‐L1) expression and an abundance of cytotoxic T lymphocytes (CTLs) expressing programmed death 1 (PD‐1).[39] To exclude autoimmunity, the immune system has evolved a variety of “preventive mechanisms”, which are expressed in the form of immune checkpoints to reduce the probability of autoimmunity and protect normal tissues from damage during immune activation.