One of the winners, Ralph Steinman, a Rockefeller University biologist recognized for his discovery of the dendritic cell and its role in adaptive immunity, died Friday but the committee did not know of his death when it made the announcement.
That calls into question the prize for Steinman, who was born in Montreal, because Nobel rules forbid awarding the prize posthumously unless the winner dies after the award is announced, CNN reported
Bruce Beutler, born in Chicago, and Jules Hoffmann, born in Echternach, Luxembourg, were honored for their discoveries concerning the activation of innate immunity, the Nobel Assembly at Karolinska Institutet said in a release.
"This year's Nobel laureates have revolutionized our understanding of the immune system by discovering key principles for its activation," the committee said in the release.
In the 1990s, Beutler and Hoffmann discovered receptor proteins that can recognize micro-organisms and activate innate immunity, the first step in the body's immune response in defending against attacks by bacteria and other micro-organisms, the committee said.
In the 1970s, Steinman discovered the dendritic cells of the immune system and their capacity to activate and regulate adaptive immunity, the later stage of the immune response when micro-organisms are cleared from the body.
The discoveries provided "novel insights" into the activation and regulation of the body's immune system, the committee said. The discoveries also made possible development of new methods to prevent and treat disease, as well as provide an understanding about why the immune system can attack its own tissues, offering clues for treatment of inflammatory diseases.
Since 2000, Beutler has been professor of genetics and immunology at The Scripps Research Institute, La Jolla, Calif.
Hoffmann was director of the Institute for Molecular Cell Biology in Strasbourg and during 2007-2008 was president of the French National Academy of Sciences.
Steinman was affiliated with Rockefeller University in New York since 1970. He was professor of immunology there since 1988 later became director of its Center for Immunology and Immune Diseases.
Notable deaths of 2014 [PHOTOS]