Gluten immunochemistry

The immunochemistry of Triticeae glutens is important in several inflammatory diseases. It can be subdivided into innate responses (direct stimulation of immune system), class II mediated presentation (HLA DQ), class I meditiated stimulation of killer cells, and antibody recognition. The responses to gluten proteins and polypeptide regions differs according to the type of gluten sensitivity. The response is also dependent on the genetic makeup of the human leukocyte antigen genes. In gluten sensitive enteropathy, there are 4 types of recognition, innate immunity (a form of cellular immunity priming), HLA-DQ, and antibody recognition of gliadin and transglutaminase. With idiopathic gluten sensitivity only antibody recognition to gliadin has been resolved. In wheat allergy, the response pathways are mediated through IgE against other wheat proteins and other forms of gliadin.

There is a growing body of evidence that the gluten-sensitive intestine differs from the normal gut, several gluten peptides can enter behind the brush border membrane cells. For example, a "33mer" of α-2 gliadin is a magnitude larger than the size exclusion of the tight junction, ω-5 gliadin peptides have been found in the blood stream of people with exercise-induced anaphylaxis, aided by salicylates. And the innate 25 is capable of reaching mononuclear cells in coeliac gut, but in normal gut is broken down by brush border peptidases. It may be this lower peptidase activity that explains the presence of these peptides behind the brush border membrane. Recently, it was found that an α-9 gliadin peptide was capable of binding the "CXCR3" receptor, increasing zonulin production and weakening tight junctions, this may explain how, generally, larger peptides can enter the gluten-sensitive gut.

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