The Nobel Prize is one of the world’s most prestigious awards, given each year to people who have made outstanding contributions to science, literature, peace, and other fields. The Nobel Prize in Physiology or Medicine honours discoveries that deepen our understanding of how the human body works or lead to major advances in health and disease treatment.

In 2025, the prize was awarded to Shimon Sakaguchi (Japan) and Mary Brunkow and Fred Ramsdell (USA) for discovering how the immune system avoids attacking the body’s own cells.

What they discovered

Our immune system protects us from infections by using white blood cells to find and destroy harmful bacteria and viruses. However, because these cells are created randomly, some could mistakenly attack the body’s own healthy tissues.

The Nobel-winning scientists discovered regulatory T cells —the immune system’s “security guards.” These special cells patrol the body and stop other immune cells from attacking healthy tissue, keeping the immune system balanced and under control.

Links to human biology and health

• Immune system regulation: This helps to explain how the body tells the difference between “self” (our own cells) and “non-self” (germs or infections).
• Autoimmune diseases: When regulatory T cells fail to work properly, the body can attack itself, causing conditions such as type 1 diabetes, multiple sclerosis, and rheumatoid arthritis.
• Cancer and transplants: Research based on this discovery is being used to help scientists create treatments that adjust regulatory T cells, for example reducing them in cancer to help the body fight tumours or increasing them to prevent organ rejection after transplants.
• Overall health: Understanding how regulatory T cells work helps explain why most people’s immune systems can protect them from infection without causing harm to their own bodies.

The BBC News article can be read here: Scientists win Nobel Prize for discovering why immune system does not destroy the body

Coverage from The Conversation can be read here: Nobel prize awarded for discovery of immune system’s ‘security guards’

More detail is available on the Nobel Prize website: They understood how the immune system is kept in check

Classroom Links and Discussion Points

Specification Link: The Immune System

Spec focus: The role of the immune system in fighting infection, including white blood cells, antibodies and antigens.

Classroom connection:

• The Nobel-winning discovery of regulatory T cells helps explain how white blood cells are controlled so they attack harmful microbes (antigens) but not the body’s own healthy cells.
• It shows that the immune system must stay balanced — strong enough to fight infection, but not so overactive that it causes damage (as in autoimmune diseases).
• This supports students’ understanding of how different parts of the immune system work together, including how white blood cells recognise and respond to invaders.

Discussion points:

1. Why does the immune system need “regulatory” cells as well as attacking cells?
2. How do white blood cells tell the difference between harmful invaders and healthy cells?
3. What might happen if the immune system loses its balance and starts attacking the body?

Specification Link: Type 1 Diabetes

Spec focus: Type 1 diabetes: the body produces insufficient insulin, or none at all.

Classroom connection:

• The Nobel Prize discovery is directly related to Type 1 diabetes, which is an autoimmune disease — the immune system attacks the cells in the pancreas that make insulin.
• Regulatory T cells normally prevent this kind of immune attack, but when they don’t work correctly, it can lead to the development of Type 1 diabetes.
• Understanding how these “security guard” cells function may help scientists develop treatments that prevent or reduce autoimmune attacks, offering hope for future diabetes therapies.

Discussion points:

1. How does the immune system cause Type 1 diabetes?
2. How could regulatory T cells help prevent or treat Type 1 diabetes in the future?
3. Why is Type 2 diabetes not considered an autoimmune disease, even though it also affects insulin levels?