Normal small intestinal mucosa is seen at the left. The mucosa involved by celiac disease (sprue) at the right has blunting and flattening of villi. Celiac disease most often becomes apparent either in infancy, or in young to middle age adults. It is diagnosed in about 1 in 3000 persons in the U.S., but the prevalence is probably much greater. It is more common in Caucasians and uncommon in Blacks and Asians. In some European populations, it may be as prevalent as 1%. About 95% of patients have the HLA-DQ2 allele, which suggests a genetic basis.

Ingestion of certain grains (wheat, rye, barley) that contain gluten with gliaden protein will cause celiac sprue. The enzyme tissue transglutamidase breaks down gliaden into peptides that, when displayed to antigen presenting cells, activate CD4 lymphocytes that produce mucosal inflammation. Autoantibodies are found in over 90% of cases, mainly of the IgA type, including: anti-tissue transglutaminase, anti-gliaden, anti-reticulin, and antiendomysial antibodies. Serologic tesing is helpful for diagnosis along with biopsy and trial of gluten-free diet.

Complications include an increased risk for gastrointestinal lymphoma and adenocarcinoma. Some patients have additional immunologically mediated conditions, including type I diabetes mellitus. About 20% of patients have dermatitis herpetiformis, with onset often in young adulthood. This is a blistering skin disease caused by IgA autoantibodies directed at dermal keratinocytes. There is an intensely pruritic papulovesicular rash most often on extensor surfaces.