Thymic nurse cells: possible sites of T-cell selection.

The precise role of the thymic microenvironment in induction and selection of the T-cell repertoire, a matter of considerable interest to immunologists, has been difficult to define. Direct cell-cell interactions between thymocytes and distinct stromal cells are an important component of this thymic microenvironment. Thymic epithelial cells, in particular, have been suspected to select immature T cells for self MHC-specificity via direct cell-cell contact. Here, Bruno Kyewski discusses the type of epithelial cells known as thymic nurse cells and their remarkable association with the thymocytes which are completely enclosed within them.