CD8A and colorectal cancer: In COAD, depletion of CD4+CD25+ regulatory T cells was reported to be able to enhance interleukin-2-induced antitumor immunity in a mouse model105 and lower CD4+/CD8+ ratio of the tumor infiltrating lymphocytes was demonstrated to be associated with better survival of colorectal cancer patients106, indicating the unfavorable effects of CD4+ T cell.