Shimon Sakaguchi is a Distinguished Professor at the World Premier International Research Initiative (WPI)-Immunology Frontier Research Center (IFReC) at Osaka University, Japan. He is an immunologist recognized for his work on the control of immune responses. He is known particularly for his discovery of regulatory T cells, an indispensable constituent of the immune system for the maintenance of immune self-tolerance and homeostasis. Sakaguchi was born in Japan in 1951, obtained an M.D. in 1976 and a Ph.D. in 1982 from Kyoto University, Japan, where he was trained as a pathologist and immunologist. 

After performing postdoctoral studies at Johns Hopkins University and Stanford University as a Lucille P. Markey Scholar, he served as an Assistant Professor in the Department of Immunology at the Scripps Research Institute. He returned to Japan in 1991 and continued his immunology research at RIKEN Institute as an Investigator of the Japan Science and Technology Agency and subsequently as the Head of the Department of Immunopathology at Tokyo Metropolitan Institute of Gerontology, Tokyo.He received Canada Gairdner International Award in 2015.