The peptide complex that generates most of the immunotoxic reaction to gluten in celiac patients are gluten immunogenic peptides (GIP). They are fragments of gluten proteins that are resistant to gastrointestinal digestion and which trigger immunologic reactions in celiac patients. GIP determination can be simplified by quantifying the peptides that are similar to those found in the α-gliadin 33-mer sequence, the dominating immunogenic peptide in wheat gluten, which react to the monoclonal antibodies G1218 and A1 used in iVYDAL In Vitro Diagnostics® (IV-D) products.
Which methodology is used to detect and quantify GIP?
The methodology is based on the detection and quantification of GIP in human samples (stools or urine) via the specific monoclonal antibodies, A1 or G12, which recognize certain epitopes in those peptides18. The techniques employed are sandwich enzyme-linked immunosorbent assay (ELISA) and lateral flow chromatography. According to information published, there is a correlation between the peptides ingested and those excreted in stools but remain undigested. GIP starts to be detected 1-2 days after gluten intake and can still be detected until four days after ingestion13.