CTLs engage in the establishment of positive crosstalk with certain immune cells, including CD4+ T cells, NK cells, M1 macrophages, and dendritic cells (DCs), while result in the establishment of negative crosstalk with immunosuppressive cells, such as cancer-associated fibroblasts (CAFs), MDSCs, M2 macrophages, regulatory T cells (Tregs), and cancer cells (9, 10). This evidence concerns the gene CD4 and cancer.