Final answer:
The high binding affinity of HLA-DQ2 or DQ8 and gluten is influenced by the structural compatibility between these molecules and the specific sequence of gluten peptides, which leads to a strong antibody-antigen interaction.
Step-by-step explanation:
The two factors that influence the high binding affinity of HLA-DQ2 or DQ8 and gluten are the structural properties of the HLA molecules and the specific sequence of the gluten peptides. HLA-DQ2 and DQ8 molecules have a particular propensity for binding proline-rich gluten peptides, which are abundant in wheat and related grains. This binding is facilitated by the presence of specific amino acids within the peptide-binding groove of the HLA molecules that can accommodate the unusual structure of gluten peptides.
Affinity refers to the strength of a single antibody-antigen interaction, and in the context of HLA-DQ2 or DQ8, this relates to their ability to bind with high affinity to certain peptides found in gluten proteins. This high affinity binding is a key factor in the pathogenesis of celiac disease, as it promotes the presentation of gluten peptides to T cells, triggering an immune response that can damage the small intestine's lining.