Technical Literature
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.
References
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