| | Re: what does it mean when you have high levels of gliadin peptide ab, IgG?
Celiac disease (CD) reflects intolerance to gliadin (a component of gluten) from wheat and related proteins from rye and barley. Most CD patients produce immunoglobulin G (IgG) and IgA antibodies that recognize endomysial (EMA), deamidated gliadin, better that unmodified gliadin, and tissue transglutaminase (tTGA). Although the IgA isotype of these antibodies usually predominates in celiac disease, individuals may also produce IgG isotypes, particularly if the individual is IgA deficient (2-5 %). Tests for deamidated gliadin and tTGA IgG and IgA offer good sensitivity and specificity. Testing for IgA and IgG antibodies to unmodified gliadin proteins is no longer recommended because of the low sensitivity and specificity of these tests for celiac disease and, recent studies have identified specific B-cell epitopes on the gliadin molecule that, when deamidated by the enzyme tissue transglutaminase, have increased sensitivity and specificity for celiac disease. However, a positive result is a strong indication that the patient has the disease but a negative result does not necessarily mean that they don not have it. False positive results are rather uncommon but false negative results can occur. This is supported from the detectable IgG anti-gliadin antibody, especially when unmodified gliadin as target are used, in approximately 21% of not CD patients with other gastrointestinal disorders (Inflammatory or Irritable bowel, diarrhea chronic, etc.) or others diseases (upper respiratory infections, poor weight gain, etc.) but also particularly workers that receiving the highest level of dust from gliadin in flour (baker, pastry cook, etc.). Anyway, the diagnosis of celiac disease cannot be based solely on gliadin antibodies, but by means of intestinal "jejunal" biopsy for to observe villous atrophy, only way to confirm the CD diagnosis.
F. Zagami MD
Member of Societe Franšaise d’Allergologie CIAB-SFA