Shimon Sakaguchi is a Distinguished Professor at the Immunology Frontier Research Center (IFReC) Osaka University, Japan. Sakaguchi obtained an MD in 1976 and a PhD in 1982 from Kyoto University, Japan, where he was trained as a pathologist and immunologist. Sakaguchi is an immunologist recognized particularly for his discovery of regulatory T cells (Tregs). His recent research has been focused on targeting Tregs for evoking and enhancing tumor immunity and for treating autoimmune and other inflammatory diseases in clinical settings. Shimon Sakaguchi’s persistent Treg research for nearly forty years has shown that Treg cells can be targeted to treat a variety of immunological diseases, establish transplantation tolerance, and evoke or enhance cancer immunity.