Work on immune system wins 2011 Nobel Prize in medicine

The 2011 Nobel Prize in medicine has been awarded to Bruce Beutler, Jules Hoffmann and Ralph Steinman for their work on the immune system.

"This year's Nobel laureates have revolutionised our understanding of the immune system by discovering key principles for its activation," the Nobel Assembly said in a statement.

Bruce Beutler of the United States and Jules Hoffmann, from Luxembourg, shared one half of the prize of 10 million Swedish crowns ($1.46 million) and Ralph Steinman, a Canadian, won the other half.

Medicine is traditionally the first of the Nobel prizes awarded each year. It will be followed in the coming days by announcements for prizes in chemistry, physics, literature, peace and economics.