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"

This is a very important day for immunology, and we have been waiting for this moment for years. It was mistakenly believed that the immune system was merely an external defence system that detected pathogens and rejected incompatible transplants. This model has changed. The immune system is an internal control and surveillance system that detects danger signals, monitors damaged, aged or tumour cells, participates in wound repair, detects pathogens and transplanted organs, but we also have cells that regulate the entire process so that it does not get out of control: regulatory T cells, which actively control that there is no autoreactive activation against our own organs and tissues. They protect us from developing autoimmune diseases by stopping other cells from activating in an uncontrolled manner.

These cells, defined by the foxp3 factor, are regulatory T cells. Dr Sakaguchi identified cells with regulatory capacity. A few years later, Dr Mary E. Brunkow and Dr Fred Ramsdell, using a mouse model that developed autoimmunity, found a mutated gene responsible for what was happening to the mouse, foxp3. A few years later, the circle was complete: regulatory T cells express foxp3, and if it is mutated, they do not function. These cells originate in two places: directly from the thymus or in the periphery.

The foxp3 mutation causes a rare X-linked syndrome that affects males, called IPEX syndrome (acronym for immune dysregulation, polyendocrinopathy, and enteropathy, associated with the X chromosome). Affected children usually show early signs of autoimmunity and involvement of many endocrine glands.

Knowledge of this new cell type has been very important for immunology and its potential applications. On the one hand, we can activate these cells to help better control autoimmunity or transplant rejection, and on the other, we can inhibit them to increase (anti-tumour) responses. These researchers have opened up a new avenue of knowledge about the immune system, as well as various possible therapies.