The IDK® Zonulin ELISA (Serum) is intended for the quantitative determination of zonulin family peptides (ZFP) in serum.

If your lab is testing at high volumes, the IDK® Zonulin ELISA (Serum) is also available in a customized bulk pack (20 plates).

The IDK® Zonulin ELISA (Serum) is Health Canada Licensed. For Laboratory Professional Use Only.

Developed by Immundiagnostik AG.

IDK® Zonulin ELISA Serum Background

Zonulin is a human protein analog to the zonula occludens toxin derived from Vibrio cholerae, which regulates tight junctions of the digestive tract. Zonulin binds to a specific receptor on the surface of intestinal epithelia and triggers a cascade of biochemical events. In turn, this induces tight junction disassembly and a subsequent increase in permeability of the intestinal epithelia, allowing some substances to pass through and activate immune reactions.

Fasano et al. found the zonulin system is more activated in people with celiac disease and type 1 diabetes mellitus. According to the research, individuals with active celiac disease show higher levels of zonulin and anti-zonulin antibodies compared to non-celiac subjects and those in remission on a gluten-free diet. An increased intestinal permeability, also colloquially called ‘leaky gut,’ is nowadays associated with metabolic syndrome, obesity, and several autoimmune, inflammatory, and neoplastic diseases. Based on the evidence, leaky gut plays a meaningful role in conditions such as multiple sclerosis, rheumatoid arthritis, asthma, and inflammatory bowel diseases.

The polyclonal antibody in our ELISA is based on the zonulin sequence, as published by Wang and di Pierro. Correspondingly, the readings of IDK® Zonulin ELISA detecting zonulin family peptides correlate well with established metabolic traits linked to increased gut permeability, such as insulin resistance and obesity.

Test Principle of the IDK® Zonulin ELISA (Serum)

The IDK® Zonulin ELISA (Serum) is based on the method of competitive ELISA.

As a first preparation step, a biotinylated ZFP tracer is added to the samples, standards, and controls. Afterward, aliquots of the treated samples, standards, and controls are transferred and incubated in microtiter plate wells coated with polyclonal anti-ZFP antibodies. During the incubation, the free target antigen in the samples competes with the biotinylated ZFP tracer for the binding of the polyclonal anti-ZFP antibodies immobilized on the microtiter plate wells. A washing step removes the unbound components.

During a second incubation step, peroxidase-labeled streptavidin, which binds to the biotinylated ZFP tracer, is added to each microtiter well. After a washing step to remove the unbound components, the peroxidase substrate tetramethylbenzidine (TMB) is added.

Finally, the enzymatic reaction is terminated by an acidic stop solution. The color changes from blue to yellow, and the absorbance is measured in
the photometer at 450 nm. The intensity of the yellow color is inversely proportional to the ZFP concentration in the sample; this means a high ZFP concentration in the sample reduces the concentration of the biotinylated ZFP tracer bound to the immobilized anti-ZFP antibodies and lowers the photometric signal.

A dose-response curve of absorbance unit (optical density, OD at 450 nm) vs. concentration is generated using the values obtained from the standard. ZFP, present in the samples, is determined directly from this curve.