AIRE and thymoma: However, active thymopoiesis in thymomas occurs under conditions favoring autoimmunity: thymomas exhibit defective expression of the autoimmune regulator AIRE [166] that normally drives ‘promiscuous’ expression of peripheral tissue autoantigens (including the AChR α-subunit [55]) in thymic epithelial cells, and thymomas have reduced or absent thymic myoid cells [108].