Part 2/8:
The positive selection step ensures that only T cells capable of recognizing self-MHC molecules survive. Thymocytes bearing T cell receptors (TCRs) with low-affinity interactions for self-peptide-MHC complexes receive survival signals, progressing toward maturity. Conversely, those with TCRs that bind too strongly to self-peptides undergo negative selection, leading to apoptosis. This negative selection is vital for eliminating self-reactive T cells, preventing autoimmunity.