Canadian-born scientist Dr. Ralph Steinman will be honoured with the Nobel Prize for Medicine after all. The Nobel Foundation says the prize awarded to Steinman, who died three days, ago still stands.

The Nobel Foundation announced Monday afternoon it has decided to honour Steinman with the award even though it normally has a policy not to award prizes posthumously.

"The events that have occurred are unique and, to the best of our knowledge, are unprecedented in the history of the Nobel Prize," the Foundation said in announcing its decision.

The Foundation selected Steinman and two co-recipients with the Nobel Prize for Medicine for their discoveries about the body's immune system. But three hours after making their announcement Monday morning, they learned that Steinman had died on Sept. 30, after a four-year battle with pancreatic cancer. He was 68.

Since 1974, Nobel statutes have stipulated that prizes cannot go to a deceased person. The only exception has been if the recipient died between the time the award was announced and the date the prize was awarded: Dec. 10, the anniversary of Alfred Nobel's death in 1896.

"The purpose of the above-mentioned rule is to make it clear that the Nobel Prize shall not deliberately be awarded posthumously," the Foundation explained.

"However, the decision to award the Nobel Prize to Ralph Steinman was made in good faith, based on the assumption that the Nobel Laureate was alive."

Steinman's finds rejected at first

Steinman was recognized for his discovery of a certain type of immune cell called dendritic cells and their role in the immune system. His research helped unlock secrets of the body's immune system and laid the groundwork for new treatments for cancer and autoimmune diseases.

His estate receives half the 10 million-kronor ($1.5 million) prize. The other portion was jointly awarded to American Bruce Beutler and French scientist Jules Hoffmann.

Beutler and Hoffmann were honoured for their discoveries about the first stages of immune responses, while Steinman was cited for discoveries that led to better understanding of the later stages.

Beutler and Hoffmann discovered in the 1990s the receptor proteins that can recognize microorganisms as they enter the body. Using fruit flies as their model, they found that these cells activate the first line of defence in the immune system, known as "innate immunity."

In the early 1970s, Steinman identified dendritic cells, which help regulate "adaptive immunity," which the next stage of the immune system's response, when the invading microorganisms are purged from the body.

Dendritic cells have the unique capacity to activate so-called T-cells. These cells help antibodies and killer cells fight infections. They also develop a memory that helps the immune system "remember" the organism and mobilize a response the next time the system comes under attack.

According to a profile in the American Society for Cell Biology newsletter, Steinman's dendritic cell theory was met by "downright hostility" by others in the field. Many of his colleagues could not reproduce his results for years. It was note until better tissue culture methods were developed that Steinman's theories made sense.

Therapeutic vaccines

The work of the three scientists has since been pivotal to the development of a new wave of "therapeutic cancer vaccines" that stimulate the immune system to attack tumours.

The research has also helped scientists understand why the immune system sometimes attacks its own tissues, laying the foundation for new ways of treating inflammatory diseases, such as rheumatoid arthritis.

As well, the findings are being used to better understand donor organ rejection, resistance to tumours, and infections such as AIDS.

"Their work has opened up new avenues for the development of prevention and therapy against infections, cancer and inflammatory disease," the Nobel committee's citation said.

Steinman was born in Montreal in 1943, and studied biology and chemistry at McGill University. He went on to study medicine at Harvard Medical School and earned an MD, magna cum laude, in 1968.

He completed his residency at Massachusetts General Hospital, and then joined The Rockefeller University in 1970 in their laboratory of Cellular Physiology and Immunology.

He became professor of immunology there in 1988, and was also director of its Center for Immunology and Immune Diseases. He was also a senior physician at the university's hospital.

Medicine, or physiology, is usually the first of the coveted Nobel prizes awarded each year.

Today's award will be followed by the physics prize on Tuesday, chemistry on Wednesday, literature on Thursday and the Nobel Peace Prize on Friday. The winners of the economics award will be announced on Oct. 10.

The prizes were established by wealthy Swedish industrialist Alfred Nobel, who invented dynamite. The economics award was created by Sweden's central bank in 1968, in Nobel's memory. The prizes will be handed out on Dec. 10.