IL-2 was discovered as a T-cell growth factor that promoted T-cell-dependent immune responses; however, more recent studies suggest that the essential role of IL-2 is to maintain functional Treg and thus control immune responses. These results are leading to new ideas about the potential of IL-2 as a therapeutic strategy in autoimmune diseases. In this issue of the European Journal of Immunology, a study further examines the role of IL-2 in immune regulation and shows for the first time that IL-2 complexes can ameliorate autoantibody-mediated autoimmunity. This commentary examines the current findings in relation to what we already know about IL-2 complexes.