Three scientists who pioneered research into the immune system and discovered novel ways their findings could be used to fight off a number of diseases, won this year’s Nobel Prize in physiology and medicine.

But one of the scientists, Ralph Steinman of Rockefeller University in New York, died three days ago, the university announced shortly after the Nobel was awarded.

The university said Steinman, 68, died from pancreatic cancer, but he was able to extend his  life by using an immunotherapy he designed.

Steinman discovered that dendritic cells, cells that act as immune-system messengers and help initiate the immune response, can play an important role in treating tumor resistance, autoimmune diseases and   infections such as HIV/AIDS.

“Signals arising from the innate immune response and sensed by dendritic cells were shown to control T-cell activation. This makes it possible for the immune system to react toward  pathogenic microorganisms while avoiding an attack on the body’s own endogenous molecules,” the Nobel Assembly at Karolinska Institute in Sweden announced in a press release on this  year’s award.

“Ralph’s research has laid the foundation for numerous discoveries in the critically important field of immunology, and it has led to innovative new approaches in how we treat cancer, infectious diseases and disorders of the immune system,” Marc Tessier-Lavigne, Rockefeller’s president, said in a press release.

Steinman’s work already paved the way for two cancer therapies that are approved by the U.S. Food and Drug Administration — Provenge for prostate cancer and Yervoy for advanced melanoma, said Dr. Jordan Berlin, clinical director of the GI Oncology Program at the Vanderbilt-Ingram Cancer Center in Nashville.

“There’s been a lot of research in this area,” Berlin added.  “On average, this therapy works really well for some people, but not everyone develops the immunity.”

While it’s unclear how Steinman applied the therapy to his own cancer, Berlin said the pancreas isn’t usually a target for dendritic cell therapy.

“There’s a significant body of data that there aren’t a lot of dendritic cells in the pancreas.  Pancreatic cancer is not an inherently immune system-type of tumor.”

Before his death, the university said Steinman was working on a way to use dendritic cells to develop vaccines.

The Nobel Committee said one-half the prize would be awarded to Steinman, and the other half to the other two scientists, Bruce Beutler and Jules Hoffmann, for their work on adaptive immunity.

Despite his death, the Nobel Assembly decided to posthumously award Steinman the prize.  On the Nobel Prize web site, the rules indicate that the prize can be awarded to a deceased person only if he or she died after being awarded the prize in October and before recieving it in December.  Steinman died on Sept. 30, shortly before Monday’s announcement.

“The Nobel Foundation thus believes that what has occurred is more reminiscent of the example in the statutes concerning a person who has been named as a Nobel Laureate and has died before the actual Nobel Prize Award Ceremony, the Nobel Assembly said in a press release.