Anti-gliadin antibodies are produced in response to gliadin, a prolamin found in wheat. In bread wheat it is encoded by three different alleles, AA, BB, and DD. These alleles can produce slightly different gliadins, which can cause the body to produce different antibodies. Some of these antibodies can detect proteins in specific grass taxa such as Triticeae (Triticeae glutens), while others react sporadically with certain species in those taxa, or over many taxonomically defined grass tribes.
| Common antibody characteristics | |
|---|---|
| Antigen source | Triticum aestivum |
| Isoform-specific characteristics of α/β-gliadin | |
| Antigen gene | Gli-X2 |
| Affected organ(s) | Intestine (Small) |
| Also affected | Epithelial extracellular matrix |
| Associated disease(s) | Coeliac disease |
| Antibody class | IgA, IgG |
| HLA associations | DQ2.5, DQ8, DQ2.2/DQ7.5 |
| Isoform-specific characteristics of γ-gliadin | |
| Antigen gene | Gli-X3 |
| Affected organ(s) | (See α/β-gliadin) |
| Associated disease(s) | Coeliac disease |
| Antibody class | IgA, IgG |
| HLA associations | DQ2.5, DQ8, DQ2.2/DQ7.5 |
| Isoform-specific characteristics of ω-gliadin | |
| Biological source | & Aegilops speltoides |
| Antigen gene | Gli-B1 |
| Affected organ(s) | Vascular, Respiratory |
| Affected tissue(s) | Serum, Dermis |
| Affected cells(s) | Mast cells, Eosinophils |
| Associated disease(s) | EIA, Baker's Allergy |
| Antibody class | IgE |
Subtypes
editAnti-gliadin IgA
editThis antibody is found in ~80% of patients with coeliac disease.[1][2] It is directed against the alpha/beta and gamma (α,β,γ) gliadins.[3] It is also found in a number of patients who are not enteropathic. Some of these patients may have neuropathies that respond favorably to a gluten elimination diet. This is referred to as gluten-sensitive idiopathic neuropathy.[4] Clinically these antibodies and IgG antibodies to gliadin are abbreviated as AGA.
Anti-gliadin IgG
editThe IgG antibody is similar to AGA IgA, but is found at higher levels in patients with the IgA-less phenotype. It is also associated with coeliac disease and non-celiac gluten sensitivity.[5][6][7]
Anti-gliadin antibodies are frequently found with anti-transglutaminase antibodies.
Anti-gliadin IgE
editThe IgE antibodies are more typically found in allergy-related conditions such as urticaria, asthma, and wheat-dependent exercise-induced anaphylaxis. The target of the most allergenic antibodies is ω-5 gliadin,[8] which is encoded by the Gli-1B gene found on the B haplome (Aegilops speltoides derived) of wheat.[9]
Diagnostic serology
editAnti-gliadin antibodies were one of the first serological markers for coeliac disease. Problematic with AGA is the typical sensitivity and specificity was about 85%. Gliadin peptides which are synthesized as the deamidated form have much higher sensitivity and specificity, creating 2 serological tests for CD that approach biopsy diagnostic in performance.[10][11]
Uses in testing
editAnti-gliadin antibodies can be generated in mice or rabbits by immunizing whole purified gliadins, proteolytic fragments of gliadin, or synthetic peptides that represent epitopes of gliadin. After developing an immune response, B-cells from mice can be fused with immortalizing cells to form a hybridoma that produces monoclonal antibodies (Mab or MoAb). Mab can be expressed in culture or via ascites fluid production to produce large amounts of a single antibody isoform.
Mab can be used to detect levels of gluten in food products. Some of these antibodies can recognize only wheat prolamins or very closely related grass seeds; others can detect antigens over broad taxa. The G12 antibody [12] is the newest example which detects the most immunotoxic fragment, a 33-mer peptide from α-2 gliadin; available from Romer Laboratories and the Spanish company Biomedal. It recognizes the toxic fraction of wheat, barley, rye and also of oat.[13]
The R5 sandwich assay is another such assay. This assay can recognize wheat, barley and rye, which makes it ideal for evaluating the presence of contaminants in gluten-free foods that do not contain oat. This antibody is a recommended testing protocol in a proposed revision of the Codex Alimentarius.
The new standards came about in part because of new sensitive and specific testing procedures.[14] These procedures are capable of detecting wheat or multiple cereals at concentrations as low as 1 part per million (PPM or 1 mg/kg). A new barley-sensitive ELISA called the R5 sandwich assay does not detect gluten in any of 25 pure oat varieties, but it does detect barley, wheat and rye.[15]
References
edit- ^ Volta U, Cassani F, De Franchis R, et al. (1984). "Antibodies to gliadin in adult coeliac disease and dermatitis herpetiformis". Digestion. 30 (4): 263–70. doi:10.1159/000199118. PMID 6391982.
- ^ Volta U, Lenzi M, Lazzari R, et al. (1985). "Antibodies to gliadin detected by immunofluorescence and a micro-ELISA method: markers of active childhood and adult coeliac disease". Gut. 26 (7): 667–71. doi:10.1136/gut.26.7.667. PMC 1432992. PMID 3894169.
- ^ Bateman EA, Ferry BL, Hall A, Misbah SA, Anderson R, Kelleher P (2004). "IgA antibodies of coeliac disease patients recognise a dominant T cell epitope of Α-gliadin". Gut. 53 (9): 1274–1278. doi:10.1136/gut.2003.032755. PMC 1774203. PMID 15306584.
- ^ Hadjivassiliou M, Gibson A, Davies-Jones GA, Lobo AJ, Stephenson TJ, Milford-Ward A (1996). "Does cryptic gluten sensitivity play a part in neurological illness?". Lancet. 347 (8998): 369–71. doi:10.1016/S0140-6736(96)90540-1. PMID 8598704. S2CID 37233945.
- ^ Crabbé P, Heremans J (1967). "Selective IgA deficiency with steatorrhea. A new syndrome". Am J Med. 42 (2): 319–26. doi:10.1016/0002-9343(67)90031-9. PMID 4959869.
- ^ Tucker NT, Barghuthy FS, Prihoda TJ, Kumar V, Lerner A, Lebenthal E (1988). "Antigliadin antibodies detected by enzyme-linked immunosorbent assay as a marker of childhood celiac disease". J. Pediatr. 113 (2): 286–9. doi:10.1016/S0022-3476(88)80266-X. PMID 3397791.
- ^ Collin P, Mäki M, Keyriläinen O, Hällström O, Reunala T, Pasternack A (1992). "Selective IgA deficiency and coeliac disease". Scand J Gastroenterol. 27 (5): 367–71. doi:10.3109/00365529209000089. PMID 1529270.
- ^ Matsuo, H.; Morita, E; Tatham, AS; Morimoto, K; Horikawa, T; Osuna, H; Ikezawa, Z; Kaneko, S; Kohno, K; Dekio, S (29 December 2003). "Identification of the IgE-binding Epitope in -5 Gliadin, a Major Allergen in Wheat-dependent Exercise-induced Anaphylaxis". Journal of Biological Chemistry. 279 (13): 12135–12140. doi:10.1074/jbc.M311340200. PMID 14699123.
- ^ Denery-Papini S, Lauriére M, Branlard G, et al. (2007). "Influence of the allelic variants encoded at the Gli-B1 locus, responsible for a major allergen of wheat, on IgE reactivity for patients suffering from food allergy to wheat". J. Agric. Food Chem. 55 (3): 799–805. doi:10.1021/jf062749k. PMID 17263477.
- ^ Agardh D (November 2007). "Antibodies against synthetic deamidated gliadin peptides and tissue transglutaminase for the identification of childhood celiac disease". Clin. Gastroenterol. Hepatol. 5 (11): 1276–81. doi:10.1016/j.cgh.2007.05.024. PMID 17683995.
- ^ Antibody Recognition against Native and Selectively Deamidated Gliadin Peptides
- ^ Belén Morón; Ángel Cebolla; Hamid Manyani; Moisés Álvarez-Maqueda; Manuel Megías; María del Carmen Thomas; Manuel Carlos López; Carolina Sousa (2008). "Sensitive detection of cereal fractions that are toxic to celiac disease patients by using monoclonal antibodies to a main immunogenic wheat peptide". American Journal of Clinical Nutrition. 87 (2): 405–414. doi:10.1093/ajcn/87.2.405. PMID 18258632.
- ^ Comino, Isabel; Ana Real; Laura de Lorenzo; Hugh Cornell; Miguel Ángel López-Casado; Francisco Barro; Pedro Lorite; Ma Isabel Torres; Ángel Cebolla; Carolina Sousa (12 February 2011). "Diversity in oat potential immunogenicity: basis for the selection of oat varieties with no toxicity in coeliac disease". Gut. 60 (First Online): 915–22. doi:10.1136/gut.2010.225268. PMC 3112367. PMID 21317420.
- ^ "Draft Revised Standard for Foods for Special Dietary Use for Persons intolerant to Gluten (at Step 8)". page 50-51. Committee on Nutrition and Foods for Special Dietary Uses. JOINT FAO/WHO FOOD STANDARDS PROGRAMME CODEX ALIMENTARIUS COMMISSION. Thirty-first Session Geneva, Switzerland, 30 June – 4 July 2008, Codex Alimentarius Commission REPORT OF THE 29th SESSION OF THE CODEX COMMITTEE ON NUTRITION AND FOODS FOR SPECIAL DIETARY USES
- ^ Hernando A, Mujico JR, Mena MC, Lombardía M, Méndez E (June 2008). "Measurement of wheat gluten and barley hordeins in contaminated oats from Europe, the United States and Canada by Sandwich R5 ELISA". Eur J Gastroenterol Hepatol. 20 (6): 545–54. doi:10.1097/MEG.0b013e3282f46597. PMID 18467914. S2CID 3128946.