The finding, published in the journal Nature Immunology, could lead to new ways to treat autoimmune diseases, in which the immune system mistakenly attacks the body's own tissues.
"This discovery is a major breakthrough in our understanding of how the immune system works," said study lead author Dr. Richard Wang, a professor of medicine at Washington University School of Medicine in St. Louis. "It could lead to new therapies for autoimmune diseases that target this fundamental process."
The immune system is a complex network of cells, tissues, and organs that work together to protect the body from infection. One of the key components of the immune system are T cells, which are white blood cells that help to identify and destroy foreign invaders.
In order to do their job, T cells must be able to distinguish between healthy tissue and foreign invaders. This process is called self-tolerance, and it is essential for preventing the immune system from attacking the body's own tissues.
Scientists have known for some time that self-tolerance is mediated by a protein called MHC-I, which is expressed on the surface of all cells in the body. MHC-I molecules bind to T cell receptors, which are proteins that are expressed on the surface of T cells.
When a T cell receptor binds to an MHC-I molecule, it sends a signal into the T cell that tells the cell to ignore that particular cell. This process is known as negative selection, and it ensures that T cells do not attack healthy tissue.
In the new study, Wang and his colleagues have identified a new protein that is involved in self-tolerance. This protein, called SHP-2, is expressed in T cells and it helps to regulate the signaling pathway that is triggered by MHC-I binding.
The researchers found that SHP-2 is essential for negative selection. In mice that lacked SHP-2, T cells were not able to ignore healthy tissue and they attacked the body's own tissues, leading to autoimmune disease.
"This finding suggests that SHP-2 could be a potential target for new therapies for autoimmune diseases," said Wang. "By targeting SHP-2, we could potentially block the signaling pathway that leads to autoimmune disease."
The researchers are now working to develop new drugs that target SHP-2. They hope that these drugs could one day be used to treat autoimmune diseases such as lupus, rheumatoid arthritis, and multiple sclerosis.
