Gluten Immunogenic Peptide (GIP) tests

Gluten Immunogenic Peptides (GIP) are fragments of gluten which are resistant to gastrointestinal digestion. These peptides trigger a series of immune reactions in coeliac patients. The resistance of GIP to gastrointestinal digestion results in significant levels of GIP excretion post gluten ingestion and therefore the presence of GIP in stool and urine samples is a reliable and direct marker for the accurate short and long-term control of a gluten-free diet (GFD).

Immunoassays based on G12 and A1 monoclonal antibodies, which react to 33-mer-like peptides of a-gliadin, the most immunogenic fragment of gluten, enable very specific and sensitive detection of GIP in stool and urine samples as a direct marker of the adherence to a gluten-free diet.

The frequency of positive GIP results also correlates with the level of mucosal damage, with a triple-positive result showing an 83% probability of Marsh II-III status. Conversely, patients who present a triple GIP negative result have a lower probability of intestinal damage (3%) compared to those with negative serology results (16%). This demonstrates that the use of GIP testing is key in achieving a level of GFD adherence which should allow intestinal recovery.