Differential processing of self-antigens by subsets of thymic stromal cells

► Self-peptides-MHC complexes expressed by thymic stromal cells direct T cell selection. ► Cortical epithelial cells are involved in positive selection. ► Medullary epithelial cells and dendritic cells drive thymic negative selection. ► These three cell types use various processes and enzymes to generate self-peptides. ► Thymic stromal cell subsets may present distinct sets of self-peptides-MHC complexes.