IFNG and neoplasm: During this process, interferon-γ (IFN-γ) from activated T cells will show an increasing trend and play a tumor immunodepression effect via the two ways, i.e., the regulation of the classic first type of major histocompatibility complex (MHC-I) to inhibit natural killer (NK) cells and the inhibition of CD8 + T cells by upregulating non-classical MHC-I molecules Qa-1b [22].