Reacción a "Nobel Prize in Medicine or Physiology awarded to Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi for understanding how the immune system is kept under control without attacking organs"

The 2025 Nobel Prize in Physiology or Medicine recognises a discovery that is absolutely essential to modern immunology: the identification and characterisation of regulatory T cells (Tregs) and their role in maintaining peripheral immune tolerance. Shimon Sakaguchi was the first to describe CD4⁺ T lymphocytes that had a key suppressive function, preventing the immune system from attacking the body's own tissues. Subsequently, the work of Fred Ramsdell and Mary E. Brunkow identified the master transcription factor that defines the identity and function of these cells, FOXP3, with mutations in this gene being responsible for serious autoimmune diseases such as IPEX syndrome.

This finding has revolutionised our understanding of how the immune system maintains the balance between defence and tolerance. Thanks to Tregs, the body can prevent autoimmune responses, control chronic inflammation and regulate the response to harmless antigens from the microbiota or allergens. Their dysfunction has been linked to multiple autoimmune, cardiovascular, metabolic and neurodegenerative diseases.

Furthermore, this knowledge has direct clinical implications. In cancer, for example, the presence of Tregs can suppress the anti-tumour response, which has led to the development of therapeutic strategies to modulate their activity. On the other hand, immunotherapy treatments, such as immune checkpoint inhibitors, can break this peripheral tolerance and trigger immune-related adverse effects (irAEs), affecting multiple organs. Thus, this Nobel Prize highlights not only a fundamental advance in basic biology, but also a central axis in precision medicine and modern immunotherapy.