Thymic Epithelial Cell Development and Its Dysfunction in Human Diseases

Figure 1

mTEC development stages and the relevant markers. The development of mTECs is roughly divided into 3 stages: CD205⁺ TEPCs first develop into progenitors specifically for mTECs characterized as high expression of claudin-3 and claudin-4 (UEA-1⁺Cld3,4^high). mTEPCs develop into immature mTEC expressing UEA-1 but low level of MHCII and costimulatory molecules CD80, and CD40. As mTECs develop further into the middle mature stage, MHCII, CD80, and CD40 expression are upregulated but still without Aire and tissue-restricted antigens (TRAs) expression. The full mature mTECs highly express MHCII, CD80 and Aire (UEA-1⁺MHCII^highCD80^highAire⁺) as well as upregulation of Aire-dependent and independent TRAs. Finally, mature mTECs enter into terminal differentiation stage as Aire⁻CD80^int/lowMHCII^low involucrin⁺ mTECs.