Thymic cortical epithelial <i>Psmb11</i> -encoded β5t in mouse and human

Psmb11-encoded β5t is a proteolytic subunit of thymoproteasomes expressed in cortical thymic epithelial cells (cTECs). β5t-containing thymoproteasomes are essential for the thymic generation of CD8-lineage cytotoxic T cells. Here, we outline the current understanding of the mechanisms underlying thymoproteasome-dependent CD8 T cell development. We focus on the cTEC-specific expression of β5t, highlighting its unique expression in comparison with the transcription factor Foxn1, which is expressed in both thymic and skin epithelial cells. Additionally, we discuss our recent engineering of monoclonal antibodies that are specific for mouse and human β5t. β5t not only provides an important machinery for CD8 T cell development but also serves as a valuable tool for further study of the biology of thymic epithelial cells in health and disease.