CD4 and neoplasm: The CD8+ clusters include effector T cells (Teff) that kill tumor cells directly, and CD4+ clusters include regulatory T cells (Treg), T follicular helper cells (Tfh) and T helper cells 1, 2, and 17 (Th1, Th2, Th17) (99), the function of Treg significantly contributed to the formation of immunosuppressive microenvironment (100, 101).