Long-Lived Innate IL-17-Producing {gamma}/{delta} T Cells Modulate Antimicrobial Epithelial Host Defense in the Colon [MUCOSAL IMMUNOLOGY]

Intestinal IL-17–producing cells, including Th17, / T, and innate lymphoid cells, are differentially distributed along the gastrointestinal tract. In this study, we show that the gut IL-17–producing / T (/ T17) cells develop before birth and persist in the tissue as long-lived cells with minimal turnover. Most colon / T17 cells express, together with V4 and CCR6, the scavenger receptor 2 and are mainly restricted to innate lymphoid follicles in the colon. Colon / T cells in mice that lack conventional dendritic cells 2 produced increased amounts of IL-17 with concomitant heightened epithelial antimicrobial response, such as the C-type lectins Reg3 and Reg3β. In the absence of / T cells or after IL-17 neutralization, this epithelial response was dramatically reduced, underlining the protective role of this unique subpopulation of innate / T17 cells in the colonic mucosa.

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