It is not the policy of the Nobel Committee to award posthumous honors unless a laureate has died after the announcement was made but before the Dec. 10th award ceremony. This year, however, the committee plans to make an exception.

On Oct. 3, the 2011 Nobel Prize in Physiology or Medicine was awarded to Canadian cell biologist Ralph M. Steinman, American Bruce A. Beutler of the University of Texas Southwestern Medical Center in Dallas and the Scripps Research Center in San Diego, and Jules A. Hoffmann, a former research director of the National Center for Scientific Research in Strasbourg, France. When the award was announced, the committee was unaware that Steinman had died three days prior. But after holding an emergency session to discuss the situation, the Swedish foundation reported that the coveted honor would remain in effect. As such, Steinman will posthumously receive his half of the $1.5 million award.

Born in Montreal, Steinman earned a bachelor’s degree from McGill University and an M.D. from Harvard Medical School. After completing an internship and residency at Massachusetts General Hospital, he joined Rockefeller University in 1970 as a postdoctoral fellow. It was there, three years later, that Steinman and his mentor, Dr. Zanvil A. Cohn, discovered dendritic cells, a new class of cells that have a unique capacity to activate T-cells, which help the body fight off infection. Steinman spent the rest of his life studying these cells to better understand how they function.

Beutler and Hoffmann were cited for their discoveries in the 1990s of receptor proteins, which can recognize bacteria and other micro-organisms as they enter the body. These proteins then activate the first line of defense in the immune system, known as innate immunity. Together, these discoveries have enabled scientists to develop better vaccines against infectious diseases, and could in the future, be used to treat arthritis, cancer, diabetes and multiple sclerosis.

Steinman was named the Henry G. Kunkel Professor in 1995, and appointed director of the Christopher H. Browne Center for Immunology and Immune Diseases in 1998. Prior to becoming a Nobel laureate, he was the recipient of the Gairdner Foundation International Award, the Novartis Prize in Immunology, the New York City Mayor’s Award for Excellence in Science and Technology, the Debrecen Prize in Molecular Medicine, the Albert Lasker Basic Medical Research Award, the Albany Medical Center Prize in Medicine and Biomedical Research and the A.H. Heineken Prize for Medicine. He also edited two volumes of the Annals of the New York Academy of Sciences (“Cancer Vaccines: Sixth International Symposium” and “Human Immunology: Patient-Based Research”).

Steinman was so determined to prove that dendritic cells were integral to the way the body fought off disease that he used a dendritic-cell based immunotherapy of his own design to battle the cancer destroying his pancreas. “Ralph worked right up until last week,” Michel Nussenzweig, the head of molecular immunology at Rockefeller, said. “His dream was to use his discovery to cure cancer and infectious diseases like HIV and tuberculosis. It’s a dream that’s pretty close.”

Steinman died on Sept. 30 at the age of 68. He is survived by his wife, Claudia, and three children.