title: It takes two to tango.
abstract: Regulatory T (Treg) cells are essential for maintaining immune tolerance. In this issue of Immunity, Haribhai et al. (2011) demonstrate that both subsets of Treg cells, natural and induced, are necessary to achieve tolerance, probably because of their nonoverlapping T cell receptor repertoires.
authors.affiliation: Molecular Pathogenesis Program, Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016, USA.
authors.forename: Angelina B
authors.initials: AB
authors.lastname: Bilate
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Lafaille