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Anti-gliadin antibodies-56

Elsevier B.V.
DOI: 10.1016/b978-044452763-9/50060-3
  • Biology
  • Medicine


Publisher Summary After anti-gliadin antibodies (AGA) discovery in the 1970s, IgA- and IgG-type AGA were the only serological test able to identify patients with coeliac disease (CD) for many years. However, AGA have no longer played a significant diagnostic role since the identification of anti-endomysial and anti-transglutaminase antibodies. Gliadin peptides, which are present in foods containing wheat, barley and rye, are modified by the tissue transglutaminase enzyme (tTG) located in the extracellular space of the intestinal mucosa; conversion of glutamine residues into glutamic acid facilitates the binding of gliadin peptides to HLA antigens of class II DQ2 or DQ8 expressed on antigen-presenting cells. In individuals, with this genetic make-up, an immune response leading to the synthesis of cytokines and specific anti-tTG and AGA antibodies can be triggered. AGA are determined by enzyme-linked immunosorbent assay (ELISA). The AGA IgA and IgG tests that use purified gluten extracts are unsatisfactory, and the different methods are not comparable. The recent identification of immunodominant gliadin epitopes are able to trigger a specific T-cell response in CD patients enabled to far more specific and sensitive AGA tests to be devised. AGA determination can be useful in patients under 5 years old; in their case, it is useful to perform this test in association with anti-tTG IgA. Positivity for AGA IgG can also be important in patients with an IgA deficiency, in whom it may be the only positive serological marker in association with anti-tTG IgG.

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