CD4 and colorectal carcinoma: While higher total T cell counts within CRC correlate strongly with survival in human samples, CD4+ T cells have been shown to have both pro- and anti-tumour behaviour in CRC.5 The effects of CD4+ T cells on CRC are most commonly thought to be enacted through their capacity to alter both the adaptive and innate immune responses in the TME, as well as the production of cytokines that affect the entire TME response.18 Different CD4+ T cell phenotypes have been correlated with improved or worsened outcomes in this disease, with a clear picture of the most advantageous profile yet to emerge.