1 Laboratory of Persistent Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA. khasenkrug@nih.gov
Leptin is a cytokine-like hormone with proinflammatory properties linked to autoimmune diseases. In this issue of Immunity, De Rosa et al. (2007) elucidate an important new role for leptin in the anergy and hyporesponsiveness of regulatory T cells.