Guinea Pig Tissue Transglutaminase Research Articles

Gluten-dependent antibodies in horses with inflammatory small bowel disease (ISBD)

Background: Equine inflammatory small bowel disease (ISBD) is an idiopathic pathologic condition seeming to increase in prevalence. Objective: To investigate the potential role of gluten in equine ISBD. Animals & Methods: Antibodies known to be important in the diagnosis of human coeliac disease (CD): IgA antibodies to human recombinant and guinea pig tissue-transglutaminase (TGA), native gliadin (AGA), deamidated-gliadin-peptides (DGPA), and primate and equine endomysium (EMA) were assessed in blood samples from three different groups of horses: ISBD affected (n = 12) on a gluten-rich diet and controls either on gluten-rich (n = 22) or gluten-poor (n = 25) diets. Significant differences (p < 0.05) between groups were assessed using the Wilcoxon test. Results: Both ISBD-affected horses and gluten-rich controls had significantly (p < 0.0004) higher hrTGA titers than gluten-poor controls. However, ISBD horses did not show significantly increased levels of any of the CD related antibodies when compared to gluten-rich controls. Nevertheless, markedly increased antibody levels (TGA, EMA and DGPA) were found in one of the ISBD horses. The introduction of a gluten-free ration in this 14-year-old warmblood stallion resulted after 6 months in the reduction of antibody levels and clinical recovery associated with improved duodenal histopathology. Conclusion: To the best of our knowledge, this is the first study assessing gluten-related antibodies in horses and results suggest a potential pathogenic role of gluten in at least some cases of equine ISBD. Clinical importance and impact for human medicine: Given serology and concurrent clinical findings, this study warrants further investigations into the immunologic basis of possible gluten-sensitive enteropathy in horses and analogy with human disease.

Systematic review: the use of serology to exclude or diagnose coeliac disease (a comparison of the endomysial and tissue transglutaminase antibody tests)

With the appreciation of the high prevalence of coeliac disease there is increasing use of serology in screening asymptomatic people and testing those with suggestive features. To compare the sensitivities and specificities of the endomysial antibody and the tissue transglutaminase antibody tests. Using electronic databases a search was made for relevant papers using the terms tissue transglutaminase and endomysial antibody. Both the endomysial antibody and tissue transglutaminase antibody have very high sensitivities (93% for both) and specificities (>99% and >98% respectively) for the diagnosis of typical coeliac disease with villous atrophy. Human recombinant tissue transglutaminase performs much better than guinea pig tissue transglutaminase. Review of studies comparing endomysial antibody with human recombinant tissue transglutaminase antibody shows that endomysial antibody more often has a higher specificity and human recombinant tissue transglutaminase antibody more often has a higher sensitivity. The human recombinant tissue transglutaminase antibody is the preferred test for screening asymptomatic people and for excluding coeliac disease in symptomatic individuals with a low pretest probability (i.e. <25%) for coeliac disease. Furthermore, it has a number of practical and financial advantages. If the pretest probability is >25%, biopsy is preferred as the post-test probability of coeliac disease with a negative test is still >2%.

The diagnostic accuracy of serologic tests for celiac disease: A systematic review

Clinicians are increasingly utilizing noninvasive serologic tests for the diagnosis and screening of celiac disease (CD). The aim of this study was to conduct a systematic review of the diagnostic performance of serologic tests for the diagnosis and screening of CD. Standard systematic review methodology was used. A literature search was conducted in MEDLINE (1966 to October 2003) and EMBASE (1974 to December 2003) databases. A weighted mean of the sensitivity and specificity along with 95% confidence intervals and summary receiver operating characteristic (ROC) curves were calculated. The pooled specificity of endomyseal antibody (EMA)-monkey esophagus (ME) or EMA-human umbilical cord (HU) was close to 100% in adults and children. The pooled specificity of transglutaminase antibody (tTG)-guinea pig (GP) and tTG-human recombinant (HR) were between 95% and 99%. IgA-EMA-ME demonstrated sensitivities of 96% and 97% in children and adults, respectively. EMA-HU demonstrated a similar sensitivity of 97% in children but 90% in adults. The pooled sensitivity of tTG-GP in adults and children was 90% and 93%, respectively. The sensitivity of tTG-HR was 98% and 96%, respectively. The performance of antigliadin antibody was inferior to that of EMA and tTG. EMA and tTG offer high sensitivity and specificity. The sensitivity of these tests appears to be lower than reported when milder histologic grades are used to define CD (below 90%). If true, the nearly perfect negative predictive value of these tests would drop. The positive predictive value of these tests is likely lower than reported when the tests are applied in low-prevalence populations.

Tissue transglutaminase antibodies in celiac disease, comparison of an enzyme linked immunosorbent assay and a dot blot assay

Aims. – The purpose of our study is to determine the sensitivity, specificity and predictive values of an enzyme linked immunosorbent assay (ELISA) and a dot blot assay for the detection of IgA class anti-tissue transglutaminase antibodies (IgA-AtTGA) and to compare these results with those of IgA class anti-endomysium antibodies (IgA-AEA), IgA class anti-reticulin antibodies (IgA-ARA) and IgA class anti-gliadin antibodies (IgA-AGA). Patients. – Serum samples from 143 patients (97 children, 46 adults) with untreated celiac disease (CD) confirmed by intestinal biopsy and 74 disease controls (64 children, 10 adults) were studied. Methods. – The anti-tissue transglutaminase antibodies were detected by dot blot assay and an ELISA using guinea pig tissue transglutaminase (gp-tTG) as antigen. The anti-endomysium antibodies were detected by an indirect immunofluorescence technique on cryostat sections of human umbilical cord. The anti-reticulin antibodies were also investigated by indirect immunofluorescence on cryostat sections of kidney, liver and stomach of rat. The anti-gliadin antibodies were determined by an ELISA. Results. – The sensitivity of an ELISA for the detection of anti-tissue transglutaminase antibodies was 86% in children and 87% in adults and the sensitivity of dot blot assay was 57% in children and 54% in adults. The specificity of an ELISA and dot blot for the detection for anti-tissue transglutaminase antibodies was, respectively, 96% and 88% lower than that of anti-endomysium antibodies (100%). The sensitivity of anti-gliadin antibodies was 97% in children and 91% in adults and their specificity was 85%. The sensitivity of anti-reticulin antibodies was 94% in children and 87% in adults. Their specificity was 100%. Conclusions. – The sensitivity and specificity of an ELISA for the detection of anti-tissue transglutaminase antibodies were better than that of dot blot assay. However, this dot blot assay could screen four celiac patients who have not had anti-tissue transglutaminase antibodies by an ELISA. The sensitivity of anti-endomysium antibodies was better than that of anti-tissue transglutaminase antibodies, anti-reticulin antibodies and anti-gliadin antibodies but in children aged less than 2 years, the sensitivity of anti-gliadin antibodies was better than that of anti-tissue transglutaminase antibodies.

Expression and rapid purification of highly active hexahistidine-tagged guinea pig liver transglutaminase

Tissue transglutaminase has been identified as a contributor to a wide variety of diseases, including cataract formation and Celiac disease. Guinea pig tissue transglutaminase has a very broad substrate specificity and therefore is useful for kinetic studies using substrate analogues. Here, we report the expression in Escherichia coli of a hexahistidine-tagged guinea pig liver tissue transglutaminase (His 6-tTGase) allowing rapid purification by immobilized-metal affinity chromatography. Using this procedure we have obtained the highest reported specific activity (17 U/mg) combined with a high yield (22 mg/L of culture) for recombinant TGase using a single-step purification protocol. Using two independent spectrophotometric assays, we determined that the K m value of the recombinant enzyme with the substrate Cbz–Gln–Gly is in the same range as values reported in the literature for the native enzyme. We have thus developed a rapid and reproducible protocol for the preparation of high quality tissue TGase.

Association of coeliac disease with primary biliary cirrhosis in Poland.

In western and northern but not southern Europe, the prevalence of coeliac disease among patients with primary biliary cirrhosis (PBC) is higher than in the general population. We analysed the prevalence of coeliac disease among patients with PBC in Poland, a central European country. In 115 patients with PBC, immunoglobulin A (IgA) antibodies against guinea-pig tissue transglutaminase (tTGA), monkey endomysium (EMA) and gliadin (AGA) were determined. In patients positive for tTGA and/or EMA, the DNA typing of HLA-DQB gene and small-bowel biopsy were performed. IgA EMA was found in one patient with PBC (0.9%, 95% CI 0-2.5%). tTGA was detected in seven patients (6%, 95% CI 1.8-10.3%). Small-bowel biopsy showed flat mucosa in one subject, who was EMA positive/tTGA negative/AGA negative, and normal histology in four tTGA-positive/EMA-negative patients. In the latter four patients, the positive tTGA result was caused by IgA reactivity to proteins other than transglutaminase. Prevalence of coeliac disease in our 115 patients with PBC was 0.9% (95% CI 0-1.9%). In one patient with silent coeliac disease presenting with the HLA-DQ2 allele, introduction of a gluten-free diet was followed by improvement in liver function tests, improvement in histology of the distal duodenum, and disappearance of EMA. Our results from Poland do not confirm a high prevalence of coeliac disease in PBC patients. Guinea-pig liver transglutaminase immunolinked assay cannot be used as a screening test for coeliac disease in PBC patients. A gluten-free diet may be helpful in restoration of liver function in patients with such an association.

Production of recombinant human tissue transglutaminase using the baculovirus expression system, and its application for serological diagnosis of coeliac disease.

Tissue transglutaminase was identified as the main autoantigen in coeliac disease (CD) but enzyme immunoassays applying the commercially available antigen from guinea pig liver show insufficient specificity and sensitivity for diagnosis as compared with endomysium antibodies (EmA). The aim of this present study was to develop a new method for the cloning and expression of human tissue transglutaminase (hu-tTG) and to test hu-tTG in the serological diagnosis of CD. Hu-tTG was cloned and expressed using a baculovirus system and SF9 insect cells. The enzyme carried a C-terminal His tag allowing efficient affinity purification from cell lysates. The recognition of hu-tTG by human sera was checked by using an enzyme linked immunosorbent assay (ELISA). For this, 35 patients with active CD were compared with 144 controls (18 patients with bioptically excluded CD, 89 blood donors, 30 patients with inflammatory bowel disease, and seven patients with cystic fibrosis). The ELISA using hu-tTG showed a sensitivity of 100% and a specificity of 98.6%. Titres of antibodies against hu-tTG (anti-hu-tTG) were positively correlated with EmA titres. All results negative for EmA were also negative for anti-hu-tTG. There were, however, EmA positive results up to a titre of 1 : 80 below the cut-off for anti-hu-tTG. For comparison, antibodies against guinea pig tissue transglutaminase (anti-gp-tTG) were determined in parallel. All patients with anti-hu-tTG below the cut-off were also negative for anti-gp-tTG. However, there were eight patients positive for anti-hu-tTG but negative for anti-gp-tTG. The new test reaches and even exceeds diagnostic efficiency of EmA for coeliac diagnosis.

Celiac disease in autoimmune cholestatic liver disorders.

In this study, serological screening for celiac disease (CD) was performed in patients with autoimmune cholestasis to define the prevalence of such an association and to evaluate the impact of gluten withdrawal on liver disease associated with gluten sensitive enteropathy. Immunoglobulin A endomysial, human and guinea pig tissue transglutaminase antibodies, and immunoglobulin A and G gliadin antibodies were sought in 255 patients with primary biliary cirrhosis, autoimmune cholangitis, and primary sclerosing cholangitis. Immunoglobulin A endomysial and human tissue transglutaminase antibodies were positive in nine patients (seven primary biliary cirrhosis, one autoimmune cholangitis, and one primary sclerosing cholangitis), whose duodenal biopsy results showed villous atrophy consistent with CD. Two of these patients had a malabsorption syndrome, and one had iron-deficiency anemia. Clinical and biochemical signs of cholestasis did not improve after gluten withdrawal in the three patients with severe liver disease. A longer follow-up of the six celiac patients with mild liver damage is needed to clarify whether gluten restriction can contribute to slow down the progression of liver disease. The high prevalence of CD (3.5%) in autoimmune cholestasis suggests that serological screening for CD should be routinely performed in such patients by immunoglobulin A endomysial or human tissue transglutaminase antibodies.

Celiac disease in autoimmune cholestatic liver disorders

OBJECTIVES: In this study, serological screening for celiac disease (CD) was performed in patients with autoimmune cholestasis to define the prevalence of such an association and to evaluate the impact of gluten withdrawal on liver disease associated with gluten sensitive enteropathy. METHODS: Immunoglobulin A endomysial, human and guinea pig tissue transglutaminase antibodies, and immunoglobulin A and G gliadin antibodies were sought in 255 patients with primary biliary cirrhosis, autoimmune cholangitis, and primary sclerosing cholangitis. RESULTS: Immunoglobulin A endomysial and human tissue transglutaminase antibodies were positive in nine patients (seven primary biliary cirrhosis, one autoimmune cholangitis, and one primary sclerosing cholangitis), whose duodenal biopsy results showed villous atrophy consistent with CD. Two of these patients had a malabsorption syndrome, and one had iron-deficiency anemia. Clinical and biochemical signs of cholestasis did not improve after gluten withdrawal in the three patients with severe liver disease. A longer follow-up of the six celiac patients with mild liver damage is needed to clarify whether gluten restriction can contribute to slow down the progression of liver disease. CONCLUSIONS: The high prevalence of CD (3.5%) in autoimmune cholestasis suggests that serological screening for CD should be routinely performed in such patients by immunoglobulin A endomysial or human tissue transglutaminase antibodies.

Human tissue transglutaminase enzyme linked immunosorbent assay outperforms both the guinea pig based tissue transglutaminase assay and anti-endomysium antibodies when screening for coeliac disease.

Anti-endomysium antibodies (EMA) and antigliadin antibodies (AGA) are widely used when screening for coeliac disease (CD), although their specificity and sensitivity are suboptimal. The guinea pig tissue transglutaminase (tTG) assay also did not prove to be superior. A newly developed enzyme linked immunosorbent assay (Celikey), based on human tTG, might however have a better performance. We therefore investigated the sensitivity and specificity of this human IgA tTG assay in 101 patients with aspecific gastrointestinal complaints and compared this to guinea pig IgA tTG, AGA and EMA. A total of 52 patients with CD were investigated and 49 patients without CD. All had a small bowel biopsy. Our results showed that human IgA tTG had a sensitivity of 96% and a specificity of 100%. Guinea pig IgA-tTG had a sensitivity of 96% and a specificity of 92%. EMA had a sensitivity of 92% and a specificity of 90%. Both IgA AGA and IgG AGA had a sensitivity of 83% whilst having a specificity of 86% and 80% respectively. both the human IgA tissue transglutaminase enzyme linked immunosorbent assay and the guinea pig IgA tissue transglutaminase assay could better identify patients with coeliac disease than IgA anti-endomysium antibodies. Although in a larger series of control patients the specificity for the human IgA tissue transglutaminase enzyme linked immunosorbent assay might fall below 100%, in our opinion this is currently the serological method of choice in identifying patients with coeliac disease in the absence of IgA deficiency.

Autoantibodies to Human Tissue Transglutaminase: Superior Predictors of Coeliac Disease

Background: Using selected sample populations, we compared sensitivity and specificity of autoantibodies to guinea pig and human tissue transglutaminase to assess if the human antigen is superior for predicting coeliac disease. Methods: Four commercial enzyme-linked immunoassay kits using human tissue transglutaminase as antigen were used to measure autoantibody levels in serum samples from untreated adult coeliacs ( n = 32). They were from a series of 130 cases diagnosed between 1997 and 1999 and chosen to bias the group towards subjects with negative autoantibodies when measured with guinea pig tissue transglutaminase as antigen. Samples from 38 control subjects (biased towards false-positive levels with guinea pig antigen) were used to compare specificity. We also assessed if human antigen kits could differentiate between levels in normal subjects and in selective IgA deficiency. Results: Sensitivity for coeliac disease in this selected group using the human antigen kits ranged from 88% to 100%. Three kits showed significantly higher specificity (82%-97%, P < 0.05) than the guinea pig antigen kit (71%) for the samples studied. No kit achieved complete separation between normal autoantibody levels and lower levels in selective IgA deficiency. Conclusions: All human antigen kits showed significantly higher sensitivity for coeliac disease compared to guinea pig antigen ( P < 0.001). Receiver operating characteristic curves confirmed the superior diagnostic accuracy of the human antigen kits.

Anti-tissue transglutaminase, anti-endomysium and anti-R1-reticulin autoantibodies-the antibody trinity of coeliac disease.

Anti-tissue transglutaminase has been recently described as the predominant autoantigen in coeliac disease. We purified serum anti-tissue transglutaminase antibodies from three patients with coeliac disease by column chromatography and eluted tissue section-bound R1-anti-reticulin antibodies from sections of rat tissue for two of these. Lastly, we generated seven mouse MoAbs to guinea pig tissue transglutaminase. Each preparation was examined for anti-tissue transglutaminase, anti-endomysium, anti-R1 reticulin and anti-gliadin antibodies. Column-purified patient antibodies and 2/7 mouse MoAbs gave characteristic anti-endomysium/anti-R1 reticulin reactivity on rat, monkey and human tissue. All positive sera gave indistinguishable patterns of immunofluorescence on rat liver, kidney and stomach, monkey oesophagus, and human umbilical cord. Anti-R1-reticulin eluted from sections showed anti-tissue transglutaminase reactivity in 2/2 cases, but 0/2 showed anti-gliadin reactivity. In both, tissue section-eluted anti-R1 reticulin gave endomysial staining on monkey oesophagus. None of the mouse monoclonals, or any of the purified patient's anti-tissue transglutaminase or anti-R1-reticulin antibody showed any reactivity with gliadin. These data confirm tissue transglutaminase as the predominant autoantigen in coeliac disease and suggest that both anti-endomysium and anti-R1 reticulin reactivities seen in coeliac disease arise due to an immune response to tissue transglutaminase. Rigorous immunoabsorption was sufficient to abrogate reactivity in the tissue transglutaminase ELISA, but failed to completely absorb anti-endomysium and anti-reticulin activity. The possibility remains that some of the anti-endomysium and anti-reticulin activity was directed against antigens other than tissue transglutaminase.

IgA anti-tissue transglutaminase: setting the stage for coeliac disease screening.

Coeliac disease is triggered in genetically predisposed individuals by the ingestion of wheat and related cereals. Affected persons raise an intestinal mucosal T-cell response against the gluten fraction of these cereals. Furthermore, they produce characteristic circulating IgA antibodies to a self-antigen present in the extracellular matrix that can be detected on tissue sections. The positive predictive value of these endomysial, reticular or umbilical cord antibodies for coeliac disease comes close to 100%. Recently, the enzyme tissue transglutaminase was identified as the main, if not sole, endomysial autoantigen in coeliac disease. Enzyme-linked immunosorbent assay tests with tissue transglutaminase from guinea pig or the recombinant human enzyme have been established that allow a standardized and quantitative determination of IgA anti-tissue transglutaminase titres. While the published assay variants report high positive and negative predictive values for coeliac disease, they were applied to preselected patients from mostly single centres. Therefore, validation and in part cross-validation of a standardized assay based on guinea pig tissue transglutaminase in 38 European and non-European centres is timely. With a sensitivity of 90% and specificity of 96% relative to local diagnostic standards the assay performed well. Considering further improvement by the use of recombinant human tissue transglutaminase as the antigen and central re-evaluation of the local standards for confirmation of coeliac disease, this enzyme-linked immunosorbent assay promises to become the primary tool for non-invasive diagnosis, therapy control and screening of coeliac disease. However, with an estimated prevalence of 1:100-1:200 of mostly atypical and subclinical coeliacs in Western populations, we are confronted with the question of how far mass screening is ethically feasible and cost effective.

Radioimmunoassay to detect antitransglutaminase autoantibodies is the most sensitive and specific screening method for celiac disease.

The aim of this study was to establish the most sensitive and specific screening method for celiac disease. We tested three methods based on different principles, which all detect autoantibodies against the same antigen (tissue transglutaminase). Sixty-two celiac children at the first biopsy (group 1), 78 celiac children on a gluten-free diet (group 2), 14 celiac children on a gluten-challenge (group 3), and 56 controls with a normal duodenal mucosa (group 4) were studied. The methods used were: 1) radioimmunoprecipitation assay using recombinant tissue transglutaminase (RIA); 2) commercial enzyme immunoassay using guinea pig tissue transglutaminase (ELISA); and 3) indirect immunofluorescence method for detection of antiendomysium antibodies (IF-EMA). RIA antitransglutaminase autoantibodies were detected in 100% of group 1, 43.6% of group 2, 100% of group 3, and none of the control subjects. ELISA antitransglutaminase autoantibodies were detected in 90.3% of group 1, 9% of group 2, 78.6% of group 3, and in none of the control subjects. IF-EMA were detected in 95.2% of group 1, 11.5% of group 2, 92.3% of group 3, and 1.8% of the controls. Our results demonstrate a very high sensitivity and specificity of the RIA method to detect antitransglutaminase autoantibodies in comparison to ELISA and IF-EMA assays. We can explain this finding with the use of human recombinant antigen and the increased capacity of the RIA method to detect low titers of autoantibodies. If our data are confirmed by studies on larger series, tissue transglutaminase RIA could be proposed as the best screening method for celiac patients.

Radioimmunoassay to detect antitransglutaminase autoantibodies is the most sensitive and specific screening method for celiac disease

OBJECTIVE: The aim of this study was to establish the most sensitive and specific screening method for celiac disease. We tested three methods based on different principles, which all detect autoantibodies against the same antigen (tissue transglutaminase). METHODS: Sixty-two celiac children at the first biopsy (group 1), 78 celiac children on a gluten-free diet (group 2), 14 celiac children on a gluten-challenge (group 3), and 56 controls with a normal duodenal mucosa (group 4) were studied. The methods used were: 1) radioimmunoprecipitation assay using recombinant tissue transglutaminase (RIA); 2) commercial enzyme immunoassay using guinea pig tissue transglutaminase (ELISA); and 3) indirect immunofluorescence method for detection of antiendomysium antibodies (IF-EMA). RESULTS: RIA antitransglutaminase autoantibodies were detected in 100% of group 1, 43.6% of group 2, 100% of group 3, and none of the control subjects. ELISA antitransglutaminase autoantibodies were detected in 90.3% of group 1, 9% of group 2, 78.6% of group 3, and in none of the control subjects. IF-EMA were detected in 95.2% of group 1, 11.5% of group 2, 92.3% of group 3, and 1.8% of the controls. CONCLUSIONS: Our results demonstrate a very high sensitivity and specificity of the RIA method to detect antitransglutaminase autoantibodies in comparison to ELISA and IF-EMA assays. We can explain this finding with the use of human recombinant antigen and the increased capacity of the RIA method to detect low titers of autoantibodies. If our data are confirmed by studies on larger series, tissue transglutaminase RIA could be proposed as the best screening method for celiac patients.

Human recombinant tissue transglutaminase ELISA: an innovative diagnostic assay for celiac disease.

Tissue transglutaminase is the autoantigen recognized by the sera of celiac patients. An enzyme-linked immunosorbent assay (ELISA) based on guinea-pig tissue transglutaminase was recently used to measure serum tissue transglutaminase antibodies for the diagnosis of celiac disease. We determine the sensitivity and specificity of an ELISA test based on the use of human recombinant transglutaminase, compared with the guinea pig transglutaminase ELISA and IgA antiendomysium antibodies. Serum samples were tested from 65 patients with intestinal biopsy proven celiac disease, from 10 patients with Crohn's disease, and from 150 healthy blood donors. Human transglutaminase ELISA identified 64 of 65 celiac patients, whereas the guinea pig transglutaminase ELISA and IgA antiendomysium antibodies identified 58 of 65 and 60 of 65 subjects, respectively. The three tests showed comparable specificity. These results proved that the human tissue transglutaminase-based ELISA represents a cost-effective strategy for identifying both symptomatic and atypical forms of celiac disease and could mean that intestinal biopsy need no longer be the gold standard for diagnosing this clinical condition. Furthermore, early identification and treatment of patients with celiac disease in an outpatient setting could have significant implications for reducing long-term morbidity and can produce major savings in future health care costs.

Human recombinant tissue transglutaminase ELISA: an innovative diagnostic assay for celiac disease

OBJECTIVE: Tissue transglutaminase is the autoantigen recognized by the sera of celiac patients. An enzyme-linked immunosorbent assay (ELISA) based on guinea-pig tissue transglutaminase was recently used to measure serum tissue transglutaminase antibodies for the diagnosis of celiac disease. We determine the sensitivity and specificity of an ELISA test based on the use of human recombinant transglutaminase, compared with the guinea pig transglutaminase ELISA and IgA antiendomysium antibodies. METHODS: Serum samples were tested from 65 patients with intestinal biopsy proven celiac disease, from 10 patients with Crohn’s disease, and from 150 healthy blood donors. RESULTS: Human transglutaminase ELISA identified 64 of 65 celiac patients, whereas the guinea pig transglutaminase ELISA and IgA antiendomysium antibodies identified 58 of 65 and 60 of 65 subjects, respectively. The three tests showed comparable specificity. CONCLUSIONS: These results proved that the human tissue transglutaminase-based ELISA represents a cost-effective strategy for identifying both symptomatic and atypical forms of celiac disease and could mean that intestinal biopsy need no longer be the gold standard for diagnosing this clinical condition. Furthermore, early identification and treatment of patients with celiac disease in an outpatient setting could have significant implications for reducing long-term morbidity and can produce major savings in future health care costs.

Antibody reactivity against human and guinea pig tissue transglutaminase in children with celiac disease.

Highly discriminatory markers for celiac disease are needed to identify children with early mucosal lesions. The purposes of this study were to evaluate the clinical potential of circulating anti-tissue transglutaminase (tTG) immunoglobulin (Ig)A antibodies in the diagnosis of childhood celiac disease and to investigate the extent of autoreactivity of these antibodies. Included in this retrospective study were samples from 22 children with biopsy-verified celiac disease, 23 control subjects with disease, and 22 healthy control subjects without any known gastrointestinal or inflammatory disorders. An enzyme-linked immunosorbent assay (ELISA) was used to measure the serum levels of IgA antibodies specific for human and guinea pig tTGs. All samples were also analyzed for antibodies to gliadin and endomysium (EMA). The concentrations of IgA specific for human and guinea pig tTGs correlated with the small intestinal villous structure and the serum levels of IgA EMA. The tTG ELISAs exhibited a high specificity and sensitivity for detection of untreated celiac disease. The human erythrocyte IgA tTG ELISA had the highest sensitivity (100%) and a specificity of 98%. The IgA EMA method had a sensitivity of 95% and the highest specificity (100%) of all tests. Our results provide additional support to the concept that anti-tTG IgA antibodies can be used as a highly discriminatory serologic marker for celiac disease and that measurements of these autoreactive antibodies may in the future be used as an alternative to the EMA test.

A transglutaminase immunologically related to tissue transglutaminase catalyzes cross-linking of cell wall proteins in Chlamydomonas reinhardtii.

The addition of primary amines to the growth medium of the unicellular green alga Chlamydomonas reinhardtii disrupts cell wall assembly in both vegetative and zygotic cells. Primary amines are competitive inhibitors of the protein-cross-linking activity of transglutaminases. Two independent assays for transglutaminase confirmed a burst of extracellular activity during the early stages of cell wall formation in both vegetative cells and zygotes. When non-inhibiting levels of a radioactive primary amine ((14)C-putrescine) were added to the growth medium, both cell types were labeled in a reaction catalyzed by extracellular transglutaminase. The radioactive label was found specifically in the cell wall proteins of both cell types, and acid hydrolysis of the labeled material released unmodified (14)C-putrescine. Western blots of the proteins secreted at the times of maximal transglutaminase activity in both cell types revealed a single highly cross-reactive 72-kD band when screened with antibodies to guinea pig tissue transglutaminase. Furthermore, the proteins immunoprecipitated by this antiserum in vivo exhibited transglutaminase activity. We propose that this transglutaminase is responsible for an early cell wall protein cross-linking event that temporally precedes the oxidative cross-linking mediated by extracellular peroxidases.

IgA anti-tissue transglutaminase as a diagnostic marker of gluten sensitive enteropathy.

AIMS: To compare and contrast the sensitivity, specificity, and positive predictive values of IgA antibodies to guinea pig tissue transglutaminase (ELISA), endomysium, and reticulin (immunofluorescence), and gliadin (ELISA), and IgG...