Q: What is cross-reactivity, and how can it affect someone with a gluten-related disorder who is following a gluten-free diet?

A: Patients with non-celiac gluten sensitivity and celiac disease may be sensitized to a broad range of dietary proteins from different foods due to cross-reactivity.

Cross-reactivity (also known as molecular mimicry) can occur when certain foods look similar enough to each other that the immune system confuses one food for another, and an immune response is triggered. An antibody, which should bind to a specific target, binds with similar-shaped parts (epitopes) on different proteins.

The first picture shows what happens when the gliadin protein molecule of wheat (labeled #1) fits into the ‘docking station’ of a wheat antibody. It fits into all 3 locks of the docking station. This is termed a reactive antibody. And in gluten sensitive individuals, the immune system is activated to make more antibodies to fight this invader.

Next we see how some foods (such as casein from dairy) can bind to a gliadin antibody. It fits into two of the three ‘docking stations’ and that is enough to trigger an immune response as if you are eating gluten.That food is called a ‘cross-reactive’ food.

And in the third drawing we see how other foods (such as rice) may bump into a gliadin antibody, but they only fit into one docking station, or no docking station, and thus will not bind to it. This is similar to putting a round peg in a square hole - can’t do it. It’s ignored by the gliadin antibody.

If you have celiac disease or non-celiac gluten sensitivity and a gluten-free diet is not producing the results you would hope for, it may be that cross-reactivity is occurring.

For further information see http://www.thedr.com/images/gs201crfoods.pdf
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