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Gliadin is a protein, found in wheat and other cereals, that is responsible for triggering the symptoms of Celiac Disease and wheat allergies in sensitive people. Antibodies made by the body against it provide a method to test for these disorders. This protein is the reason many people follow a gluten-free diet.
Gluten is a combination of seed proteins in wheat that lets bread rise properly. There are two proteins that comprise gluten, and one of them is gliadin. Unfortunately, many people have a genetic predisposition to be sensitive to this protein. At its most severe, this manifests as Celiac Disease — a disease of the small intestine in which food is not absorbed properly. There are many other symptoms associated with this disease, including neurological disorders, but it can be reversed once gluten is removed from the diet.
In people with Celiac Disease, the body makes gliadin antibodies that can be detected in a test for the presence of the disorder. There are different kinds of gliadins, and the body makes different types of antibodies depending on the type of protein present. Together, these are referred to as anti-gliadin antibodies (AGA). An entirely different antibody is produced in response to each of the different forms of the protein, which is just one of a group that can cause people to develop allergies to wheat.
The specificity of AGA antibodies is about 85%. In an effort to make more specific antibodies, researchers have experimented with using purified gliadin, or its breakdown fragments, as the target for making antibodies. The breakdown products of proteins are called peptides, and a gliadin peptide — made from the part of the protein that is highly effective at inducing antibodies — has been chemically synthesized. Such synthetic peptides can be much better at inducing antibody production than using the whole protein.
Recent studies with these antibodies show that more people suffer from sensitivity to gliadin than originally thought. While not having Celiac Disease, 10-15% of Americans suffer from a variety of symptoms. A positive reaction to these antibodies indicates that they need to consider changing their diet, and perhaps try to eliminate all gluten.
Aside from diagnosing disease in humans, a highly specific gliadin antibody can be used to detect the presence of gluten in foods. This is highly significant, since wheat gluten tends to contaminate many food items that one would not expect to contain any form of wheat. New procedures can detect wheat at values as low as one part per million (ppm). This test can help provide gluten-free products to people who suffer from Celiac Disease or allergies to gluten.