Complement system studies in adult coeliac disease.

Detailed complement system studies were performed in 22 patients with adult coeliac disease. Activation products of C3 were observed in the fresh sera of all untreated patients, while only 4 had activation products of factor B of the alternate pathway. Levels of C4 and C3 were lower than normal mean, but only the depression of C4 reached a level of statistical significance. The amounts of circulating C3 activation products were significantly reduced when the patients were on a gluten-free diet. There is thus evidence that activation of the classical pathway of the complement system takes place in adult coeliac disease, and there is an association between gluten ingestion and the complement activity. We suggest that a possible mechanism of tissue injury in this disease is activation of complement factors by a humoral immune reaction to dietary gluten in the intestinal wall.