The good and bad of your immune system

Your immune system must be balanced to work properly. If it’s too sluggish, it can’t fight invading microbes, such as bacteria and viruses. If it’s overly aggressive, it can attack the body’s own cells, giving rise to autoimmune diseases such as rheumatoid arthritis, as well as type 1 diabetes and cancer.

For more than twenty years, Shimon Sakaguchi had been trying to understand how our immune systems stay in balance and why they sometimes don’t. This year he won the Nobel Prize in Physiology or Medicine for discovering “how we keep our immune system under control so we can fight all imaginable microbes and still avoid autoimmune disease” in the words of the Nobel committee. (Immunologists Mary E. Brunkow and Fred Ramsdell shared the prize.)

What Sakaguchi finally discovered was an elusive type of T cell—which he called regulatory T cell (or Treg) that prevents the immune system from overacting and causing harm. (T cells are a type of white blood cell that helps protect the body from infection and cancer.) The newly discovered Treg cells act as “peacekeepers” to stop the immune system from entering self-destruct mode—aka autoimmunity. The scientists also discovered a gene called FOXP3 which is required for the formation of Treg cells. (Humans who lack this gene develop a rare—and deadly—disease called IPEX.)

Because of these discoveries, potential new treatments are currently being developed to either suppress overactive immune responses or enhance the immune response. More than 200 clinical trials on such therapies are now in the works. Good news.

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