CD4 and colorectal carcinoma: Reported mechanisms for these associations in CRC include 1) TLR4-induced initiation of signaling pathways that lead to the secretion of inflammatory cytokines such as TNF-alpha and IL-8 (52, 53), 2) expression of NF-κB, which inhibits apoptosis and stimulates cell proliferation (54), 3) NK T-cell inhibition (55), and 4) recruitment of myeloid-derived suppressor cells that suppress CD4 T-cells (56, 57).