T cells, a special class of white blood cells, defend the body and kill infected or foreign tissue. In an organ called the thymus, they learn to distinguish between proteins that are helpful and those that are harmful. However, autoimmune diseases like multiple sclerosis or diabetes can result when T cells falsely label beneficial proteins as foreign.
Recent research from Cold Spring Harbor Laboratory Fellow Hannah Meyer elucidates how the human thymus creates the list of friendly proteins that T cells should not target. Her team made history by identifying the RNA molecules responsible for creating the list that shields healthy tissue from T cells.
Their discovery could lead to more effective autoimmune disorder treatments by highlighting crucial distinctions between immune systems that function properly and those that do not.
T cells need to have a full understanding of the proteins they might come across in the human body to attack the correct targets. An estimated 20,000 different types of proteins can be produced by humans.
T cells must be taught to recognize each of these favorable proteins before they are ready to leave the thymus to combat infections. The thymus must therefore produce all 20,000 proteins. No other organ in the human body produces every possible protein, they only produce the proteins required for their specific organ function.
Usually, it is very strictly regulated which proteins are made in which cells and tissues. Thymus cells make all of them to ensure the immune system functions properly.”
Hannah Meyer, Cold Spring Harbor Laboratory
Meyer concentrates on the thymus because of its function in preventing autoimmune diseases as well as battling cancer and infections. Meyer expects that more research into the proteins produced in the thymus may help understand and cure these disorders.
Carter, J. A., et al. (2022) Transcriptomic diversity in human medullary thymic epithelial cells. Nature Communications. doi.org/10.1038/s41467-022-31750-1.