What does Cross-Reactivity of coffee and gluten mean?? If you are sensitive or intolerant to gluten this means that your immune system has tagged the gluten protein as something that is foreign and needs to be attacked as an invader. This leads to allergies, intestinal pain, inflammation, and digestive disorders. Over time, your immune system that has created antibodies to the gluten protein will also create antibodies to proteins that are *similar* to gluten and attack them