The molecular basis of celiac disease.

Celiac disease is caused by inflammatory, gluten specific T cell responses in the small intestine. Invariably such responses are HLA-DQ2 or HLA-DQ8 restricted, providing an explanation for the strong association between celiac disease and these HLA-class II alleles. It is now clear that some native gluten sequences can bind to HLA-DQ2/8 and induce T cell responses. In addition, modification of gluten peptides by the enzyme tissue transglutaminase results in high affinity HLA-DQ2/8 binding peptides that can induce T cell responses. Thus, gluten molecules contain a large number of immunogenic peptides and this is likely to play an important role in the breaking of oral tolerance to gluten.