Figure 1

In the thymus autoreactive T cell progenitors, which recognize self antigens with their T cell receptor (TCR), are either deleted or converted into thymic-derived regulatory T cells (tTreg). Both tTreg and non-self reactive naïve T cells can migrate to the intestine. Some of these naïve T cells recognize commensal antigens with their TCR. Dependent on the bacteria and the cytokine milieu, these naïve T cells are then either differentiated into effector/memory T cells or iTreg cells. Additionally DC and Tr1(Foxp3-; IL-10+) cells can team up with tTregs and iTregs in order to maintain the immune homeostasis in the intestine.