Nordic Life Science 1
26 A DELICATE BALANCE BETWEEN DEFENSE AND SELF-HA
RM The Nobel Prize in Physiology or Medicine 2025 honors fundamental discoveries about how the body prevents the immune system from doing harm, leading to important medical progress in autoimmune diseases and cancer. T E X T B Y MA L I N O T MA N I M ARY BRUNKOW, Fred Ramsdell, and Shimon Sakaguchi have received this year’s Nobel Prize in Medicine for discoveries about peripheral immune tolerance and the identification of its key component, the immune system’s security guards, the regulatory T cells (Tregs). “Our immune system deals with a delicate balancing act, it must protect us against invading pathogens with full force while avoiding attacking the body’s own tissues. The laureates discovered a fundamental mechanism that limits detrimental immune responses to “self ”. Tregs are key to preventing autoimmune reactions in the body’s peripheral tissues,” explains Nils Landegren, Assistant Professor and Group Leader at the department of Medical Biochemistry and Microbiology at Uppsala University and SciLifeLab. “The importance of this mechanism becomes tragically clear in patients who lack functional Tregs and develop severe, multi-organ autoimmune disease from early childhood. This discovery has fundamentally reshaped our understanding of immune tolerance and may open new avenues for treating autoimmune diseases,” adds Landegren. A new class of T cells At the beginning of the 1980s, Professor Shimon Sakaguchi, who at the time worked at the Aichi Cancer Center Research Institute in Nagoya, Japan, set out to understand the role of the thymus in T cell development. During his experiments he found that there appeared to be T cells that could protect the mice he studied from autoimmune diseases. Sakaguchi believed that the immune system must have some form of security guard that calms down other T cells and keeps them in check. About a decade later, in 1995, he presented his results in the Journal of Immunology. The results showed that these cells are THE NOBEL PRIZE // MEDICINE