Tissue transglutaminase autoantibody detection in human saliva: a powerful method for celiac disease screening

Abstract

Objective To test the possibility of detecting tissue transglutaminase autoantibodies (tTG-Abs) in saliva with a novel sensitive fluid-phase radioimmunoassay (RIA).Study design Paired saliva and serum samples from 39 patients with celiac disease (CD), at the first biopsy (Group 1: 28 females, mean age 11.5 ± 11.1 years); 32 controls with a normal duodenal mucosa (Group 2: 18 females, mean age 8.1 ± 3.6 years); and 32 healthy volunteers (Group 3: 21 females, mean age 31.7 ± 9.8 years) were studied for tTG-Ab presence. Limit of positivity for salivary assay was calculated according to the 99th percentiles of Group 2 control children and was expressed as an autoantibody (Ab) index.Results Salivary tTG-Abs were found in 97.4% of the patients with CD and in 100% of the corresponding serum samples. All Group 3 subjects were negative with both saliva and serum assays. A correlation between saliva and serum tTG-Ab titers was found (r = 0.826, P = .0014).Conclusions This study demonstrates that it is possible to detect salivary tTG-Abs in CD with a non-invasive, simple to perform, reproducible and sensitive method. (J Pediatr 2004;144:632-6) C eliac disease (CD) may appear in a classic presentation, with gastrointestinal complaints and growth failure or with extraintestinal manifestations and ''atypical forms'' 1 characterized by anemia and short stature, 2,3 or with a silent form, more frequent in first-degree relatives of patients with CD. 4 The prevalence of CD is increased in subjects with elevated aminotransferase levels, 5,6 autoimmune diseases, 7,8 and chromosomal aberrations. 9,10 Complications of long-standing CD may include osteopathy, 11 endocrinopathy, 12 infertility, low birth weight infants, 13,14 cancer, 15 and dilated cardiomyopathy and other forms of heart failure. 16 CD has a high prevalence in the general population (0.55% in Italy), often in an asymptomatic form. 17 To reduce the risks associated with prolonged gluten exposure, CD should be diagnosed early, on the basis of the result of one or more intestinal biopsies. 18 Patients with CD receiving a gluten-containing diet have increased levels of anti-gliadin (AGA), anti-endomysium (EMA), 19 and anti-tissue transglutaminase autoantibodies (anti-tTG-Ab). 20 Serum AGA have proved to be effective in the identification of children at risk for CD, but less so in adult screening. 21 EMA are more specific than AGA but are observer-dependent, and sometimes they are not found in children with CD younger than aged 2 years. 19 The recent identification of tTG as the main autoantigen recognized by EMA 22 has lead to the development of various studies that suggest an important role for this enzyme in the etiopathogenesis of CD. 23,24 Several methods have been proposed for the detection of humoral anti-tTG immunoreactivity in CD. 20,[25][26][27] The most sensitive assays to detect tTG-Abs were those using human recombinant tTG in a fluid-phase radioimmunoassay (RIA) format. 26,27 Attempts have been made in assaying CD-related Ab in saliva, [28][29][30][31][32][...

The anti-transglutaminase auto-antibodies in children�s saliva with a suspect coeliac disease: clinical study

“…Lenander-Lumikari has shown that individuals with CD secrete lower amounts of IgA, IgG and amylase; in his study, he hasn't found significant differences between coeliac and healthy subjects, as also it has been said more recently by Mina (8,13). Some studies, over the last decade, have also demonstrated the presence of anti-tTG auto-antibodies in the saliva of coeliac children (14)(15)(16). This study has took into consideration the antitTG auto-antibodies in the saliva of 17 children with suspected CD, in order to attest the usefulness of the salivary anti-tTG as diagnostic and predictors markers of the CD.…”

An electrochemical immunoassay for the screening of celiac disease in saliva samples

“…In this regard, saliva has a concentration of IgA about ten times lower than serum [14], thus requiring a more sensitive assay; in addition, we often obtained high current values analyzing negative saliva samples (unpublished results), probably due to non-specific adsorption phenomena. Saliva contains, in fact, high concentrations of different glycoproteins [19,20], such as mucins or salivary agglutinins (SAG), that increase the viscosity of samples and bind other proteins.…”

“…They were collected and stored as reported in [14]. Before analysis, each aliquot of saliva, once thawed, was briefly centrifuged at 3,000 rpm for 3 min at 4°C.…”

“…Before analysis, each aliquot of saliva, once thawed, was briefly centrifuged at 3,000 rpm for 3 min at 4°C. For the sake of clarity, the effectiveness of the saliva RIA method was previously demonstrated in [14], analyzing saliva and serum samples taken from the same donors also submitted to duodenal biopsy. The clinical specificity of the saliva versus serum RIA was 100 %, whereas the clinical sensitivity was 97.4 %.…”

“…This system shows good sensitivity and specificity and is suitable for point-of-care testing (POCT), but it is an invasive and only qualitative test [12,13]. At moment, a fluid-phase radioimmunoassay is the only method able to detect anti-tTG antibodies in saliva samples with high specificity and sensitivity [14], and it was successfully utilized in CD screening of about 6,000 primary school children [13]. Saliva is, in fact, a good specimen for screening analysis because it is easily obtained by non-invasive techniques [15], especially suitable for the diagnosis and follow-up of CD in pediatric patients [16].…”