Oral tolerance: Is it all retinoic acid?

Abstract

Oral tolerance has been argued to depend on "special" presentation of antigen in the gut. New studies support this idea by showing that the catalysis of vitamin A into retinoic acid (RA) in gut-associated dendritic cells (DCs) enhances the transforming growth factor (TGF)-β-dependent conversion of naive T cells into regulatory T (T reg) cells and also directs T reg cell homing to the gut. These results reveal new tolerance mechanisms that will aid the use of T reg cells in the clinic. JEM © The Rockefeller University Press.