chemoattractant receptor, CXCR3. Gliadin binds to, blocks and displaces a factor, I-TAC, that binds this receptor. In the process it recruits more CXCR3 receptor, increases MyD88 and zonulin expression. The factor it displaces, I-TAC, is a T-cell attractant. This peptide may also be involved in increased risk for type 1 diabetes as zonulin production is also a factor. This triggering of zonulin ultimately results in the degradation of tight junctions allowing large solutes, such as proteolytic resistant gliadin fragments to enter behind the brush border membrane cells. One study examined the effect of ω-5 gliadin, the primary cause of WD-EIA, and found increased permeability of intestinal cells. Other studies show that IgE reactivity to ω-5 gliadin increases greatly when deamidated or crosslinked to transglutaminase. HLA Class I restrictions to gliadin HLA class I restrictions to gliadin are not well characterized. HLA-A2 presentation has been investigated. The HLA-A antigens can mediate apoptosis in autoimmune disease and HLA A*0201 in with the HLA-DQ8 haplotypes has been documented. The class I sites were found on the carboxyl end of gliadin at positions 123-131, 144-152, and 172-180. The involvement of class I responses may be minor, since antibodies to transglutaminase correlate with pathogenesis and recognition of extracellular matrix and cell surface transglutaminase can explain the destruction within coeliac disease. This process involves antibody-dependent cellular cytotoxicity. With regard to a receptor called FOS, euphemistically called the "Death Receptor", enterocytes appear to overexpress the receptor in coeliac lesions, there is speculation that Class I presentation of gliadin, tTG or other peptides that invokes signalling. The role of class I receptor in cell-mediated programmed cell (enterocyte) death is not known. MIC These proteins are called MHC class I polypeptide-related sequence A and B. Discovered by sequence homology analysis these proteins are found on the surface of enterocytes of the small intestine, are believed to play a role in disease. Studies to date have revealed no mutation that would increase risk for MICA. HLA-DQ recognition of gluten HLA-DQ proteins present polypeptide regions of proteins of about 9 amino acids and larger in size (10 to 14 residues in involved in binding is common for gliadin) to T lymphocytes. Gliadin proteins can be adsorbed by APC. After digestion in the lysozomes of APCs, gliadin peptides can be recycled to the cell's surface bound to DQ, or they can be bound and presented directly from the cell surface. The major