[hanklazard]

< The antigen will always destroy your cells, autoimmune response or not.

In regards to autoimmunity, antigens themselves don't destroy cells--antigens only provoke a pathogenic immune response when presented to the immune system.

< Celiac is typically an autoimmune response to Gliadin protein as a result of human leukocyte activation genes HLA-DQ2.2/2.5 or HLA-DQ8. In either case, it is happening at the cellular level for every cell that comes into contact with the protein.

You're not wrong with regards to the celiac, gliadin, and the association with the HLA alleles that you've mentioned. However, I'll point out that those particular HLA genes make up MHC class II proteins. These are the proteins present on what are known as professional antigen presenting cells, a small group of specialized immune cells throughout the body. MHCII proteins present foreign antigen to TH4 cells (helper T cells) which can then activate a larger immune response.

Epithelial cells of the intestinal villi have not classically been thought to be professional antigen presenting cells, and thus should have very small levels of expression. I found one older study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC508181/) that suggests these intestinal villi cells can express class II but nothing since. All of this suggests that the pathogenesis of celiac disease is not as simple as intestinal villi cells expressing high levels of the HLA proteins encoded by the genes you mentioned and provoking a direct immune response--rather, like seemingly every autoimmune disease, the story is much more complicated and likely involves the activation of CD4+ T cells, generation of pathogenic autoantibodies, and a larger network of pro-inflammatory players.