Anti-idiotypic response in mice expressing human autoantibodies

Celiac disease is an autoimmune illness characterized by intestinal mucosal injury and malabsorption precipitated by dietary exposure to gluten of some cereals. The immune response is based on both cellular and humoral components, although the former seem to be more important in the pathogenesis. The autoantibody response is directed at the enzyme tissue transglutaminase, tTG or TG2, which possibly play a role in the onset of the disease. In this study we sought to develop an animal model in which to analyze the immunological regulation and significance of anti-TG2 antibodies, by expressing specific human single-chain antibody fragments in mice using adeno-associated virus vectors. Upon vector injection in the skeletal muscles, high and persistent systemic levels of anti-TG2 antibodies were obtained. Mice injected with vectors encoding antibodies also recognizing rodent TG2, also developed a strong anti-idiotypic response. This finding raises the question of whether an anti-idiotypic response to anti-TG2 antibodies is a factor associated with celiac disease.