CD8A and neoplasm: It was found that certain gut microbiota enhanced the expression of major histocompatibility complex (MHC) class I in DC, followed by activation of interferon gamma (IFN-γ)+CD8+ T cells, and increased the number of (IFN-γ)+CD8+ tumor-infiltrating lymphocytes in the TME to inhibit the growth of CRC (Tanoue et al., 2019).