Herein we present the case for the existence of a thymic cortical epithelial cell that
possesses an unusual gene transcription. It produces tissue‐specific proteins that have their
usual physiological functions outside the thymus and presents them, as well as household
proteins, to the differentiating thymocytes. We suggest that this specialized cell enforces
tolerance to most self‐proteins by causing release of a signal for programmed cell death to
thymocytes that express receptors for these self‐antigens.