Mary E. Brunkow

In 2025, the Nobel Prize in Physiology or Medicine was awarded jointly to Dr. Mary E. Brunkow, Dr. Fred Ramsdell, and Dr. Shimon Sakaguchi for their groundbreaking discoveries about the immune system’s self-control mechanism — specifically, how the body prevents its own immune defenses from turning inward and attacking healthy tissue. (source: Reuters)

This discovery — centered on a special class of cells known as regulatory T cells (T-regs) — has reshaped our understanding of autoimmune diseases, organ transplant rejection, and cancer immunotherapy.

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Early Life and Education

Mary Elizabeth Brunkow was born and raised in the United States, where she displayed an early fascination with biology and human health.

She completed her undergraduate studies in molecular biology before pursuing advanced research in immunogenetics. Her doctoral and post-doctoral work in immunology in the 1990s focused on the genetic regulation of immune responses, setting the stage for her landmark discovery. (source: Science News)

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The Discovery — Cracking the Code of Immune Tolerance

In the late 1990s, while working as a research scientist at Amgen, Brunkow and her colleague Fred Ramsdell identified a gene known as FOXP3, a master regulator critical for the development of regulatory T cells.

Around the same time, Shimon Sakaguchi in Japan had discovered these cells functionally. The convergence of these findings revealed the mechanism of immune tolerance — how the immune system knows when to attack and when to stand down. (source: AP)

What Are Regulatory T Cells?

Regulatory T cells (T-regs) act like immune system peacekeepers. They suppress excessive immune reactions that could damage healthy cells.

When these cells malfunction or are absent — as Brunkow’s work showed — the body develops autoimmune disorders such as Type-1 diabetes, lupus, multiple sclerosis, and rheumatoid arthritis. (source: Nature)

Why It Was Revolutionary

Before Brunkow’s discovery, scientists could observe autoimmune diseases but not explain the molecular brake that normally prevents them.

By linking the FOXP3 gene mutation to immune dysregulation, Brunkow’s research turned immunology on its head — providing the foundation for new diagnostics and therapies that manipulate the immune system safely. (source: Reuters)

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From the Lab to Lifesaving Therapies

The implications of Brunkow’s discovery are vast:

• Autoimmune Disease Treatments: Drugs that boost T-reg activity are now used in early-stage clinical trials for lupus and multiple sclerosis.
• Organ Transplantation: T-reg modulation helps reduce dependence on lifelong immunosuppressants.
• Cancer Immunotherapy: Inversely, temporarily disabling T-regs can unleash immune cells to better attack tumors. (source: The New York Times)

Today, Brunkow’s work underpins the rapidly expanding field of immune modulation therapy, bridging fundamental science with real-world medicine.

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Personal Traits and Legacy

Colleagues describe Dr. Brunkow as a quietly determined scientist, more focused on precision than publicity.

Her former research partners credit her meticulous data analysis and perseverance through experimental setbacks for the success of their discovery.

“Mary had the rare ability to see patterns in immune behavior that others missed — she connected genetics with cell dynamics at just the right moment,” said a colleague from Amgen in a retrospective interview. (source: Science Daily)

Brunkow’s Nobel recognition also serves as a milestone for women in biomedical science, inspiring a new generation of female researchers in immunology, genetics, and molecular biology.

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The Nobel Committee’s Citation

“For their discoveries revealing how the immune system achieves self-tolerance through regulatory T cells, preventing autoimmune disease and enabling future immune therapies.” (source: Nobel Committee)

During her Nobel acceptance speech, Brunkow emphasized collaboration and humility in science:

“The immune system is our most elegant paradox — a protector that must also know mercy. Understanding that balance was not the work of one mind, but of many.” (source: Reuters)

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Global Impact

The discovery of the FOXP3 gene and T-regs continues to drive breakthroughs in:

Field	Application
Medicine	New therapies for autoimmune disorders (Type-1 diabetes, lupus, Crohn’s disease)
Transplantation	Improved graft tolerance and lower rejection rates
Oncology	Novel immunotherapies targeting T-reg suppression to enhance cancer defense
Biotechnology	Engineered immune cells for precision medicine

(source: Nature, AP, The Lancet)

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Frequently Asked Questions (FAQ)

Q1. What is Dr. Mary E. Brunkow known for?

She co-discovered the genetic basis for regulatory T cells, explaining how the immune system prevents autoimmunity.

Q2. When did she win the Nobel Prize?

She received the 2025 Nobel Prize in Physiology or Medicine, shared with Fred Ramsdell and Shimon Sakaguchi. (source: Reuters)

Q3. Why is her work important?

It opened the door to new treatments for autoimmune diseases and improved understanding of immune balance.

Q4. What gene did she identify?

The FOXP3 gene, crucial for the function of regulatory T cells.

Q5. How has this discovery affected medicine?

It has led to new therapeutic strategies that can fine-tune the immune response — calming it in autoimmune diseases or boosting it against cancer.

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Conclusion

Dr. Mary E. Brunkow’s Nobel Prize honors not only a scientific milestone but a philosophy of perseverance and collaboration.

Her work illuminates one of biology’s deepest mysteries — how our bodies distinguish “self” from “other.”

In a world facing new immune challenges — from pandemics to cancer — Brunkow’s discovery continues to guide the search for balance, healing, and hope.

Sources: Reuters, AP, The New York Times, Nature, The Lancet, Nobel Committee, Science Daily.