Origins of Medullary Thymic Epithelial Cells

(University of Basel, June 06, 2013)

Medullary thymic epithelial cells (mTECs) allow the thymus to ensure that the body’s T cells are able to distinguish between potentially harmful foreign antigens and those that are produced by the body itself. A Swiss-Japanese research team suggests that mTECs do not share a common progenitor with cortical-thymic TECs (cTECs) that produce T cells, but may actually evolve from them. Very little is presently known about how cTECs and mTECs develop, or how they relate to each other. A Swiss-Japanese research team now reports that mTECs derive from cells that already express β5t, a proteasome subunit that is densely concentrated in cTECs and no other cell types, including mTECs themselves. This finding suggests that mTECs may evolve from cTECs. This finding has not only implications for how mTECs develop, but also how they may have evolved.