Autoantibodies in coeliac disease: tissue transglutaminase—guilt by association?

Abstract

Endomysial antibodies are a hallmark of coeliac disease. The existence of autoantibodies whose titres fluctuate with ingestion of gliadin is enigmatic. Gliadin seems to drive this antibody secretion as endomysial antibodies are produced in biopsy samples cultured with a peptic/tryptic digest of gliadin.1 The phenomenon of endomysial antibodies has been explained by molecular mimicry between gliadin and the endomysial antigen, or unmasking of cryptic epitopes in the endomysial antigen upon exposure to gliadin.1 2Recently, Dieterich and colleagues identified tissue transglutaminase (tTG) as the antigen for endomysial antibodies.3 Their data indicate that tTG forms complexes with gliadin, and they hypothesise that neoepitopes in the complex between gliadin and tTG initiate an immune response that is finally directed against gliadin and tTG.3 4 Based on the observation that tTG and gliadin form complexes, we would like to propose an alternative mechanism for the production of antibodies to tTG. The prevailing view of B cell tolerance states that tolerance to soluble self-antigens, in contrast …