Tissue Transglutaminase (tTG)
1. Intended use
The tissue Transglutaminase IgA test is a rapid ELISA method for the detection of circulating IgA antibodies to tTG.
2. Explanation of the Test
Gluten-sensitive patients develop IgA antibodies to gliadin and to a component of the gut endomysium. Recently, tissue Transglutaminase, a calcium-dependent enzyme that catalyses the transamidation of specific polypeptide-bound glutamine residues, has been identified as the unknown endomysial antigen. Interestingly, gliadin is the preferred substrate for this enzyme creating antigenic neo-epitopes, which are thought to generate the immune response in genetically susceptible individuals.
The immunological detection of autoantibodies to tTG is a useful tool in the diagnosis and follow-up of coeliac disease. The presence of autoantibodies to tTG closely correlates with the detection of anti-endomysial antibodies by indirect immunofluorescence.
3. Principle of the test
Human recombinant tissue Transglutaminase (tTG) is bound to microwells. Antibodies against the coated antigen, if present in diluted patient sample, bind to the respective antigen. Washing of the microwells removes unbound unspecific serum and plasma components. Horseradish peroxidase (HRP) conjugated anti-human antibodies immunologically detect the bound patient antibodies, forming a conjugate/antibody/antigen complex. Washing of the microwells removes unbound conjugate. An enzyme substrate in the presence of bound conjugate hydrolyses to form a blue colour. The addition of an acid stops the reaction forming a yellow end-product. The intensity of this yellow colour is measured photometrically at 450 nm. The amount of colour is directly proportional to the concentration of antibodies present in the original sample.
Sblattero D et al (2000) Human recombinant tissue transglutaminase ELISA: an innovative diagnostic assay for coeliac disease. Am J Gastroenterol 95 (5),1253-7
Sardy M et al (1999) Recombinant human tissue transglutaminase ELISA for the diagnosis of gluten-sensitive enteropathy. Clin Chem, 45 (12), 2142-9
Dieterich, T et al (1998) Autoantibodies to tissue transglutaminase as predictors of coeliac disease. Gastroenterology, 115, 1317- 1321
Sulkanen S et al (1998) Tissue transglutaminase autoantibody enzyme-linked immunosorbent assay in detecting coeliac disease. Gastroenterology, 115:1332-1328
Dieterich, T et al (1997) Identification of tissue transglutaminase as the autoantigen of coeliac disease. Nature Medicine, 3(7), 797-801
Sollid, M et al (1997) Autoantibodies in coeliac disease: tissue transglutaminase - guilt by association? Gut, 41, 851-852
Maki, M (1997) Tissue transglutaminase as the autoantigen of coeliac disease Gut, 41(4), 565-566
Marsh, M N (1997) Transglutaminase, gluten and coeliac disease: Food for thought. Nature Medicine, 3 (7), 725-726
Maki, M et al, (1988) Changing pattern of childhood coeliac disease in Finland Acta Paediatr. Scand., 77, 408-412
Guandalini, S et al, (1989) Diagnosis of coeliac disease: Time for a change? Arch Dis Child 64, 1320-1325
Caiulo, L et al, (1991) Riv Ital Pediatr 17, 691-695
Greco, L et al, (1991) Multi-centre study on the frequency of identified cases of coeliac disease in Europe and in the Mediterranean area. ESPGAN,
Capri, 11-12 October 1991
Ceccarelli, M et al, (1991) Is childhood disease under-diagnosed? Eur J Paediatrics 150,821-822