The Nobel assembly on Monday gave its prize in physiology or medicine to three researchers who were recognized for their work in unlocking some key intricacies and mechanisms of the immune system.

The work by researchers – which took place between 1973 and 1998 - concerned the immune system’s response to attacks at early and later stages. The work has opened new paths for the development of prevention and therapy against infections, cancer, and inflammatory diseases, the Nobel Assembly at Karolinkska Institutet said.

The Nobel Assembly said the discoveries “have revolutionized our understanding of the immune system by discovering key principles for its activation.”

In the 1990s, researchers Bruce Beutler and Jules Hoffman, working separately but in related fields, discovered receptor proteins that can recognize bacteria or other microorganism that attack the immune system. Their discovery concerns the first step in the body’s immune response.

The other half of the award went to Ralph Steinman, who in 1973 discovered the dendritic cells of the immune system and their “unique capacity to activate and regulate adaptive immunity, the later stage of the immune response during which microorganisms are cleared from the body.”’

In 1996 Jules Hoffman discovered that the so-called Toll gene needed to be activated in order for fruit flies to successfully defend against bacteria or fungi.

In 1998, Beutler, a medical doctor and scientist, along with colleagues discovered the lipopolysaccharide (LPS) receptor similar to the Toll gene. LPS is a bacterial product which can cause septic shock, a condition which involves overstimulation of the immune system.

When the receptor binds to LPS, inflammation occurs. When LPS doses are excessive, septic shock occurs.

“These findings showed that mammals and fruit flies use similar molecules to activate innate immunity when encountering pathogenic microorganisms,” the Nobel assembly said in a released statement. “The sensors of innate immunity had finally been discovered.
Numerous similar discoveries have been made since that time.

In 1973, Ralph Steinman showed that the presence of dendritic cells had a unique capacity to activate T cells. T cells play a part in adaptive immunity and “develops immunologic memory against many different substances.”

Steinman’s subsequent work, along with that of others was able to show that signals from the innate immune response and sensed by dendritic cells controlled T cell activation. As such, the immune system can respond toward pathogenic microorganisms while avoiding an attack on the body’s own molecules.