Thymic epithelial cells induce Fas-independent activation apoptosis of thymocytes.

Co-cultivation of human thymocytes with homologous thymic epithelial cells (TEC) resulted in apoptosis of thymocytes and increase of CD25 expression. TEC supernatant also induced these effects. Fraction of apoptotic cells was enriched by CD69+ cells but not by CD95+ cells. Thymocytes of mice MRL-lpr/lpr bearing mutant form of gene Fas were sensitive to apoptosis induction in co-culture with TEC in the same degree as thymocytes of mice bearing Fas gene of wild type. Apoptosis of murine thymocytes can be induced by co-cultivation with both murine and human TEC.