Immunosuppressive γδ T cells foster pancreatic carcinogenesis

γδ T cells are a subset of CD3+CD4？CD8？lymphocytes expressing a peculiar T-cell receptor (TCR) that recognizes peptide as well as non-peptide antigens in an MHC-unrestricted fashion.1 A priori, the diversity of γδ TCRs would be greater than that of conventional αβ TCRs and B-cell receptors (BCRs) combined, in both mice and humans. However, such a potential diversity is never fully realized. Indeed, γδ T cells develop under a very strict endogenous and microenvironmental control, which allows for the emergence of TCRs that are encoded by a single Vγ and Vδ gene and often exhibit limited, if any, junctional diversity.1 Thus, at least in some aspects, γδ T cells are more similar to cells of the innate immune system like natural killer (NK) cells than to αβ T lymphocytes and B cells. Moreover, γδ T cells are much less abundant in the peripheral blood than αβ T cells, but are particularly enriched in epithelial tissues like the skin and intestinal tract, where they can account of up to 50% of CD3+ cells.