What is the peripheral immunological tolerance that has justified the Nobel Prize today?

Science Writing.- The discoveries related to “peripheral immunological tolerance” made by three scientists have justified today the awarding of the Nobel Prize in Medicine or Physiology, but what is it? It is a mechanism of the immune system that prevents the body from attacking its own tissues.

It also prevents, according to some of the world’s leading scientific texts on immunology (such as Janeway’s Immunobiology), the body from overreacting to some antigens that are not, in principle, particularly dangerous and that act in the periphery of the organism.

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The Nobel Assembly at the Karolinska Institute in Stockholm has today announced the award of the 2025 Nobel Prize in Physiology or Medicine to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi “for their discoveries concerning peripheral immunological tolerance.” The immune system learns to differentiate between its own organisms (autoantigens) and foreign ones (pathogens), and central tolerance is established inside the human body, which, if functioning normally, is capable of eliminating some types of lymphocytes (white blood cells fundamental in the immune system to identify and combat pathogens). But the immune system is not able to eliminate all lymphocytes, that’s where peripheral tolerance becomes important, which tries to prevent those lymphocytes that ‘escaped’ from attacking the body’s own tissues, which is fundamental to maintain the balance between the immune response against infections and to prevent autoimmune diseases.