Trafficking of regulatory T cells in the intestinal immune system

Intestinal tolerance toward dietary antigens and the microbiota critically depends on regulatory T cells (T-reg cells). To exert their function, T-reg cells need to get into the proximity of their target cells foremost within lymphoid organs and the lamina propria in the small and large intestines. Thus, T-reg-cell-mediated immunosuppression is intrinsically linked to cell migration and localization. However, the gut lamina propria not only constitutes an effector site but also actively influences T-reg-cell function. In particular, gut-resident macrophages take an active role in shaping the T-reg-cell pool. Here, the author summarizes recent observations to suggest that T-reg-cell migration not only directs cells to sites of immunosuppression but also allows for the coordinated shaping of the T-reg-cell population.