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.
As epithelial cells now express a broad spectrum of self-proteins that can be encountered across the body, immature T-cells are examined for their capacity to recognize and interact with these self-proteins and self-MHC molecules. If any T-cell demonstrates strong affinity for both, it undergoes programmed cell death to prevent autoimmune reactions.