Published: 5 October 2025NobelPrize.orgScience & Technology
Nobel Prize in Physiology or Medicine 2025 Awarded to Brunkow, Ramsdell and Sakaguchi for Discovery of Regulatory T Cells
The Nobel Prize in Physiology or Medicine 2025 was awarded jointly to Mary E. Brunkow (USA), Fred Ramsdell (USA) and Shimon Sakaguchi (Japan) for their fundamental discoveries relating to peripheral immune tolerance. The announcement was made on October 6, 2025 by the Nobel Assembly at Karolinska Institutet in Stockholm.
The laureates identified 'regulatory T cells' (Tregs), which act as the immune system's security guards, preventing immune cells from attacking the body's own tissues. Shimon Sakaguchi first identified these cells and their crucial role in preventing autoimmune disease. Mary Brunkow and Fred Ramsdell then discovered that mutations in the FOXP3 gene in both mice and humans result in severe autoimmune disease. Sakaguchi later linked these discoveries by showing that the development and function of regulatory T cells depend on FOXP3.
Their work has opened new avenues for treating autoimmune conditions such as multiple sclerosis, type 1 diabetes, and rheumatoid arthritis. The prize amount was 11 million Swedish kronor, shared equally among the three laureates.
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The Nobel Prize in Physiology or Medicine 2025 was awarded for discoveries related to which of the following?
Explanation · Correct answer BThe 2025 Nobel Prize in Physiology or Medicine was awarded to Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi for their fundamental discoveries relating to peripheral immune tolerance, specifically the identification of regulatory T cells (Tregs) and their dependence on the FOXP3 gene.
Frequently asked questions
Who won the Nobel Prize in Physiology or Medicine 2025?
The Nobel Prize in Physiology or Medicine 2025 was awarded jointly to **Mary E. Brunkow** (USA), **Fred Ramsdell** (USA), and **Shimon Sakaguchi** (Japan) for discoveries on **peripheral immune tolerance** and the identification of **regulatory T cells (Tregs)**.
What are regulatory T cells and why is their discovery Nobel-worthy?
**Regulatory T cells (Tregs)** are immune cells that prevent the body from attacking its own tissues. Sakaguchi's identification of Tregs in the 1990s and Brunkow-Ramsdell's discovery of the **FOXP3 gene** revealed the molecular basis of immune self-tolerance.
What is FOXP3 and what disease does its mutation cause?
**FOXP3** is the master regulator gene of Treg development. Mutations in FOXP3 cause **IPEX syndrome** (Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked) — a severe fatal autoimmune condition discovered by Brunkow and Ramsdell in **2001**.
What autoimmune diseases can be treated using Treg research?
Treg research has opened treatment avenues for **multiple sclerosis**, **type 1 diabetes**, **rheumatoid arthritis**, and **cancer immunotherapy** — by either boosting or suppressing regulatory T cell activity as needed.
What is IPEX syndrome and how is it related to Nobel Medicine 2025?
**IPEX syndrome** is a rare fatal autoimmune disorder caused by **FOXP3 gene mutations**, discovered by Brunkow and Ramsdell in 2001. Sakaguchi showed Foxp3 controls Treg development. Together these discoveries formed the core of the **2025 Nobel Prize in Medicine**.
