Thymocytes appear to ignore class I major histocompatibility complex antigens expressed on thymus epithelial cells.

BALB/c nu/nu mice were grafted with embryonic 14-day-old C57BL/6 thymi which were transplanted either nontreated or after elimination of hemopoietic cells with 2-deoxyguanosine. In both types of grafts host cells developed normally into functional thymocytes. Thymocytes from 2-deoxyguanosine-treated but not from untreated grafts contained as many cytolytic T lymphocyte precursors specific for class I MHC antigens on thymus epithelium as normal BALB/c thymocytes. As cytolytic T lymphocyte precursors were neither suppressed nor activated in these grafts it is concluded that thymocytes ignore class I MHC antigens expressed on thymus epithelium.