CD4 and colonic neoplasm: Regarding its dampening influence on the antitumor immune response, it has been demonstrated that the absence of IL-6 in host mice in an orthotopic CT26 colon tumor model resulted in the increased expression of MHC class I molecules on the surfaces of tumor cells and in the intratumoral accumulation of mature dendritic cells, CD4+ helper T cells, and CD8+ cytolytic effector T cells [91].