As these epithelial cells now present a large variety of self-proteins that could be encountered across the body, the immature T-cells are tested for affinity to self-protein and self-MHC. If any T-cell has strong affinity for self-protein and self-MHC, the cell undergoes apoptosis to prevent autoimmune function.
Since epithelial cells now express a diverse array of self-proteins that can be found throughout the body, immature T-cells are evaluated for their ability to recognize and bind to these self-proteins and self-MHC molecules. If any T-cell shows a strong affinity for both, it is eliminated through apoptosis to prevent autoimmune responses.