Regulatory T cells are key players in the maintenance of intestinal homeostasis. A defect or a lack of activation of regulatory T cells can lead to mucosal inflammation. Many subsets of T cells with a regulatory function are present in the intestinal mucosa.1 Yio and Mayer2 explored during his career the role of intestinal epithelial cells (IEC) in regulating mucosal immune responses. He and his group identified a molecule expressed on normal IEC that appears to play a role in the activation of antigen nonspecific CD8+ suppressor T cells.