Phenotypic analysis of T cells infiltrating colon cancers: Correlations with oncogenetic status.

Colorectal cancers (CRC) develop in the face of an important immune system associated with the intestinal mucosal tissue. The immune response against the tumor has been proposed to affect the prognosis of patients undergoing treatment for CRC. In this study T cells infiltrating the tumor were compared with T cells populating the unaffected neighboring mucosal tissue and cells from the peripheral blood. We observed that T cells from the tumor harbor an activated phenotype, with engagement of the NKG2D pathway in CD8 T cells. We show that mucosal and tumor-infiltrating T cells are enriched in NKG2D CD4 T cells, which exhibit cytotoxic functions. Finally, T cell populations in the tumor were modified according to its oncogenetic status, with higher percentages of CD8 T cells isolated from patients with microsatellite instable tumor status.