IFNG and neoplasm: NK cells expressing high levels of surface CD56 (CD56bright) that represent less than 10% of peripheral blood NK cells are more immature and have an immunomodulatory role with high production of cytokines and chemokines, whereas the major NK cell subset (about 90%) are mature CD56dimCD16+ NK cells characterized by high cytotoxic capacity and IFN-γ production after direct contact with tumour or virus-infected target cells [56, 57].