What HLA is found in patients with celiac disease and how does it contribute to the development of the disease?
Celiac disease occurs as an autoimmune reaction to wheat gluten/gliadin by T and B lymphocytes in the gut of genetically predisposed individuals. It is a relatively common disease affecting 1:70 to 1:300, most often in individuals of Northern European ancestry. HLA-DQ2 and/or -DQ8 (usually in linkage with HLA-DR3 ) is seen in 99% of celiac disease patients compared with 40% of the normal population. Dietary gluten is partly digested by gastric enzymes to form a 33-amino acid peptide that is deaminated by tissue transglutaminase increasing its immunogenicity. The immunogenic gliadin peptide is then presented in the context of HLA-DQ2 or DQ8 to CD4+ T cells, resulting in interferon-γ release and inflammation, altered gut permeability, and villous atrophy. Only 66% have characteristic bowel symptoms, whereas others will present with arthritis, vitamin D or B12 deficiency, iron deficiency anemia, cerbellar disease, infertility, or peripheral neuropathy. It is more likely to occur in patients with other HLA-DR3- associated autoimmune diseases such as Sjögren’s, type I diabetes mellitus, autoimmune thyroid disease, or autoimmune liver disease.