In MC38 tumor-bearing mice, oral administration of OMV-Ag-mFC significantly improved the tumor-suppressing microenvironment: tumor-infiltrating CD3+ T cells, CD3+CD8+ T cells, CD3+CD4+ T cells and CD11c+ DCs were increased, and immunosuppressive CD3+CD4+CD25+ Tregs were suppressed considerably. The gene discussed is CD4; the disease is neoplasm.