The thymus is a small organ at the top of the chest, in which T cells develop. These developing T cells are exposed to practically all of the possible proteins that they may encounter in the body. This exposure ensures that T cells recognizing the body’s own antigens are deleted, as they constitute a potential threat and may cause autoimmunity, whereas functionally competent T cells that do not bind any of the self-proteins survive. Traditionally, most attention has been paid to the thymic epithelial cells, which are primarily responsible for this process. However, the thymus could not form without a network of fibroblast cells to form this critical support structure. Until recently those fibroblasts were relegated to supporting players within the thymus.
The new study from the Holländer’s lab led by Adam Handel and Stanley Cheuk uses single cell sequencing approaches to focus on those frequently overlooked fibroblasts cell-by-cell across mouse and human development.