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Freiburg immunologist explains the significance of the research that will be awarded the 2025 Nobel Prize in Medicine

On Monday, October 6, 2025 at 11:30 a.m., it was announced that the Nobel Prize in Physiology or Medicine 2025 will be awarded to three scientists working on an important control mechanism of the immune system. Prof. Dr. Stephan Ehl, Director of the Institute of Immunodeficiency at the Medical Center - University of Freiburg, explains what the findings mean for patients:

"The outstanding research work of Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi on peripheral immune tolerance has made a decisive contribution to understanding how the immune system controls its activity and avoids self-destruction," says Stephan Ehl.

"The researchers identified and characterized regulatory T cells (Tregs) and thus established a concept of specialized immune cells that actively suppress immune responses. They showed that a congenital deficiency of Tregs leads to severe autoimmune diseases, which illustrates their central role in maintaining immunological balance.

These findings provide concrete approaches for new therapies aimed at preventing or modulating autoimmune reactions - for example in type 1 diabetes, multiple sclerosis or rheumatoid arthritis - as well as preventing the rejection of organ transplants. At the same time, tumors use mechanisms of immune tolerance to escape immune surveillance. A deeper understanding of peripheral immune tolerance will therefore also help in oncology to develop therapies in the future that reactivate the immune system in a targeted manner without jeopardizing its natural protective function."

About the person:

Prof. Dr. Stephan Ehl is a paediatrician, Director of the Institute for Immunodeficiency at the Medical Center - University of Freiburg, Professor of Paediatric Immunology at the Faculty of Medicine - University of Freiburg, spokesperson for the Collaborative Research Center 1160 "Impath" and a member of the Cluster of Excellence Centre for Integrative Biological Signalling Studies -CIBSS at the University of Freiburg. Ehl is also a member of the German National Academy of Sciences - Leopoldina.

Caption: Prof. Dr. Stephan Ehl
Image source: Medical Center - University of Freiburg / Britt Schilling