The relationship between flow cytometry and the 2025 Nobel Prize in Physiology or Medicine.

The 2025 Nobel Prize in Physiology or Medicine was awarded to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi "for their discoveries concerning peripheral immune tolerance" ( NobelPrize.org ).

They identified a group of immune system cells, called regulatory T cells (or Tregs), that play a crucial role in controlling the immune system so that it does not attack the body's own healthy tissues, which can lead to autoimmune diseases.

Key findings include:

1. In 1995, Sakaguchi identified that, in addition to central tolerance (elimination of autoreactive T cells while still in the thymus), there is a peripheral mechanism that regulates autoimmune responses—and that these regulatory T cells are part of this control system.

2. Brunkow and Ramsdell demonstrated that the Foxp3 gene is an essential marker for the development of these Tregs. Mutation in Foxp3 causes severe autoimmune diseases, such as IPEX syndrome.

Flow cytometry was essential for identifying and characterizing regulatory T cells.

Sakaguchi, in his first published articles on Tregs (1995 and 2001), used a 2-color panel (FITC and PE) to label CD25 and T lymphocyte markers such as CD5, CD4, and CD8 (Figure 1).

It's fascinating to observe how much a two-color panel has contributed to the development of world science. Furthermore, it's quite astonishing to see that in 30 years we've expanded a two-color panel to the possibility of using 50 colors or more.