Development and Validation of a Gluten ELISA Kit Using Polyclonal Antibodies Configured in Sandwich Format

Introduction: Gluten has become a growing concern due to an apparent increase in the frequency of gluten intolerance. For this reason, the FDA has recently implemented regulations pertaining to gluten content in foods labeled “gluten-free.”  Existing gluten detection kits possess inherent limitations with respect to misestimation of barley residues (hordein) and/or cross reactivity with common food commodities.  Accordingly, a rapid test kit capable of detecting gluten residues without cross-reacting concerns would greatly improve gluten HACCP for the food industry. 

Purpose: To develop a rapid and facile sandwich-based ELISA kit for detection of gluten residues derived from wheat, barley, and rye which does not cross-react with common food commodities. 

Methods: Polyclonal antibodies were raised against prolamin fractions from wheat, rye, and barley. The polysera from these individually immunized goats were immunopurified and then blended and developed into a sandwich-format immunoassay for the detection of gluten (wheat, barley, and rye) from complex food matrices. The final kit was validated and then compared with commercial Gluten ELISA kits based on Skerrit and R5 monoclonal antibodies.

Results: The MEI/IEH sandwich-based quantitative gluten ELISA kit consists of a 26 min test method (including extraction and assay operation). The kit detected spiked gluten residues (ROD 0.1 -100 ppm, R² = 0.9686) derived from wheat, barley, and rye at near equal stoichiometry. Validation analysis using a panel of prolamins derived from various cereals indicated that the kit is capable of broadly detecting gluten from relevant gluten sources without cross-reactivity with soy, sorghum, lupin, corn, or oats.

Significance: Gluten intolerance is a growing concern, as evidenced by recent efforts by the FDA and TTB to regulate gluten levels in foods labeled “gluten-free.” The MEI/IEH sandwich-based gluten ELISA provides the food industry with an improved tool to rapidly and accurately detect contaminating gluten residues so as to ensure compliance with Federal regulations and provide safer foods for individuals with coeliac disease.