IL18 and cancer: IL-18 can also form a positive loop with interferon-γ (IFN-γ), which exerts a series of immune activities for cancer suppression, including the activation of cytotoxic T lymphocytes (CTLs), the production of granzyme B, and the inhibition of immunosuppressive cytokines (Mantovani et al. 2019; Nakanishi 2018).