Two US researchers, Mary E. Brunkow and Fred Ramsdell, and Japanese researcher Shimon Sakaguchi, win the Nobel Prize in Medicine for research into how the immune system is kept in check, identifying the immune system's ‘security guards’. "Both teams here have shown extraordinary persistence in pursuing their ideas knowing that there was something there to find and how important it is to contribute funding so these important discoveries can be done", says Marie Wahren-Herlenius, a member of the Nobel Committee, after an official announcement. IMAGES AND SOUNDBITES