The 2011 Nobel Prize in Physiology or Medicine was awarded today to Bruce Beutler at the Scripps Research Institute in California, Jules Hoffmann at the French National Center for Scientific Research and Ralph Steinman at The Rockefeller University in New York City. Beutler and Hoffman helped to elucidate innate immunity, the non-specific array of initial responses by the body’s immune system that can recognize invading microorganisms as being foreign and try to destroy them.

Steinman investigated dendritic cells and their key role in adaptive immunity, the specialized response to specific invaders that comes into play when innate immunity isn’t enough. Thanks to adaptive immunity infected cells get wiped out, and exposure to a specific pathogen can leave us with long-standing protection against that pathogen.

The detailed understanding of the immune system provided by the new Nobel laureates has given other researchers the ability to improve vaccines and to attempt to stimulate immune reactions to cancer. Their insights also inform efforts to damp down the immune system when it becomes too zealous, which can lead to excessive inflammation and autoimmunity.

[UPDATE, 1:00 PM ET]
Steinman, 68, died on September 30, three days before today's announcement, after battling pancreatic cancer for four years. "His life was extended using a dendritic-cell based immunotherapy of his own design," The Rockefeller University spokesman Joe Bonner said in a prepared statement.

This unanticipated turn of events raises questions about the status of Steinman's award going forward. According to Nobel Committee rules, the prize can be awarded posthumously only if the laureate dies between the October announcement and the award ceremony, held annually on December 10 in Stockholm, Sweden. The Rockefeller University itself only "learned this morning from Ralph's family that he passed," Marc Tessier-Lavigne, the university's president, said in a prepared statement. Because the committee was apparently unaware of Steinman's death prior to today's announcement, the group will make a decision about the status of the award to Steinman—and associated prize money—shortly. Steinman was listed last year as a likely winner in Thompson Reuter's annual shortlist predictions.

[UPDATE, 4:00 PM ET]

The Nobel foundation has announced that Steinman will remain a prize winner.

For more on how dendritic cells work, see "The Long Arm of the Immune System," from the November 2002 issue of Scientific American.

The innate immune system and its links to inflammatory disease are covered in "Immunity's Early-Warning System," from the January 2005 issue of
Scientific American.

And for Beutler's comment in 2006 on the idea of genetic regulation of excessive immune reactions, read "Gene Tied to Out-of-Control Immune Response."

(Additional reporting by Katherine Harmon)