Recombinant human tissue transglutaminase for diagnosis and follow-up of childhood coeliac disease

Evaluation of screening for coeliac disease in children with juvenile idiopathic arthritis

AIM

To study the prevalence of coeliac disease (CD) in children with Juvenile idiopathic arthritis (JIA), by screening a population-based cohort of children with JIA using autoantibodies against tissue transglutaminase (anti-TG2).

METHODS

All children diagnosed with JIA in three Swedish counties, with disease onset between 2007 and 2014, were included prospectively. Serum levels of IgA anti-TG2 antibodies, IgG anti-TG2 antibodies, and total IgA were analysed. Children with positive levels of IgA anti-TG2 antibodies and children with IgA deficiency in combination with positive levels of IgG anti-TG2 antibodies were referred to the paediatric gastroenterology unit for gastroscopy and small intestine biopsy.

RESULTS

A total of 216 children were included, and analysis of IgA and IgG anti-TG2 antibodies was performed in 213 children. Three children were diagnosed with CD prior to the diagnosis of JIA, and three additional children were found through screening, resulting in a CD point prevalence of 2.8% (95% CI 0.6-5.0%).

CONCLUSION

We found a point prevalence of CD close to previous described prevalence in the general population of Swedish children. Therefore, general screening for CD in children with JIA is not supported by our data. However, this study shows that asymptomatic CD in children with JIA may be found by screening.

Dietitian visits were a safe and cost-effective form of follow-up care for children with celiac disease

AIM

This study compared follow-up protocols for paediatric celiac disease (CD) led by either paediatricians or dietitians at Swedish university hospitals.

METHODS

We followed 363 CD patients under 18 years at the university hospitals in Malmö (n = 140) and Lund (n = 79) between 2011 and 2013 and after they merged to become Skåne (n = 144) between 2014 and 2016. Both Lund and Malmö provided regular paediatrician follow-up visits, whereas Skåne provided mainly dietitian-led visits.

RESULTS

Children at Lund were followed for a mean of 1.0 ± 0.5 visits per year, compared to 0.7 ± 0.6 at Malmö (p < 0.0001) and 0.9 ± 0.6 at Skåne (p = 0.11). The ratio of annual paediatrician to dietitian annual visits was 1.4:1.0 at Lund, which was higher than Malmö (0.9:1.0; p = 0.0017) and Skåne (0.6:1.0; p < 0.0001). There was no difference in the prevalence of non-compliant patients between the clinics (p = 0.26, Malmö 13.6%, Lund 10.1%, Skåne 7.6%). Tissue transglutaminase autoantibody levels reversed equally over time at all three clinics after the subjects started a gluten-free diet (r = -0.55, p < 0.0001). The total mean annual cost per patient was lowest at Malmö and highest at Lund (p < 0.0001).

CONCLUSION

Dietary compliance was similar regardless of whether care was provided by a dietitian or paediatrician. Dietitian-led follow-up visits may provide lower long-term costs.

Antibody Concentrations Decrease 14-Fold in Children With Celiac Disease on a Gluten-Free Diet but Remain High at 3 Months

BACKGROUND & AIMS

Celiac disease can be identified by a serologic test for IgA against tissue transglutaminase (IgA-TTG) in a large proportion of children. However, the increased concentrations of antibody rarely normalize within the months after children are placed on a gluten-free diet (GFD). Early serologic predictors of sufficient adherence to GFD are required for optimal treatment.

METHODS

In a prospective study, we observed the response to a GFD in 345 pediatric patients (67% girls; mean age, 8.4 y) who underwent duodenal biopsy to confirm or refute celiac disease from October 2012 through December 2015. Baseline serum samples were tested centrally for IgA-TTG and IgG against deamidated gliadin. Follow-up serologic analyses of children on a GFD were performed about 3 months later.

RESULTS

The geometric mean concentration of IgA-TTG decreased from 72.4-fold to 5.2-fold the upper limit of normal (ULN), or by a factor of 14.0 (95% CI, 12.0-16.4). A substantial response (defined as a larger change than the typical variation in patients not on a GFD) was observed in 80.6% of the children. Only 28.1% of patients had a substantial response in the concentration of IgG against deamidated gliadin. Concentration of IgA-TTG remained above 1-fold the ULN in 83.8% of patients, and above 10-fold the ULN in 26.6% of patients with a substantial response.

CONCLUSIONS

Serum concentration of IgA-TTG decreases substantially in most children with celiac disease within 3 months after they are placed on a GFD, but does not normalize in most. This information on changes in antibody concentrations can be used to assess patient response to the diet at short-term follow-up evaluations. Patients with a substantial response to a GFD often still have high antibody levels after 3 months. German Clinical Trials Registry no. DRKS00003854.

Lack of Utility of Anti-tTG IgG to Diagnose Celiac Disease When Anti-tTG IgA Is Negative

OBJECTIVES

Guidelines for diagnosing celiac disease (CD) recommend initial testing with a highly sensitive serologic test for anti-tissue transglutaminase immunoglobulin A antibodies (tTG IgA). When the probability of CD is high, IgA deficiency should be considered. The 2 approaches to address this include measuring "both tTG IgA and tTG IgG" or measuring "total IgA." We aim to assess the utility of an isolated positive tTG IgG result in diagnosing CD.

METHODS

We conducted a retrospective review of patients undergoing serologic testing for CD from January 1997 to June 2014. Patients with positive tTG IgG and negative tTG IgA were included. Moreover, all patients who had any other positive CD-specific serologic findings were excluded. Demographics, clinical presentation, tests, and biopsy results were recorded.

RESULTS

The indication for checking celiac serology was gastrointestinal symptoms in 172 of 233 patients, iron deficiency anemia in 12, and high-risk screening in 48. Small bowel biopsy was performed in 178 patients (77%); 160 had normal results and 18 had histologic changes suggestive of enteropathy. Nine patients had increased intraepithelial lymphocytes, and 9 had partial villous atrophy. Only 6 cases of CD were, however, confirmed. The utility of isolated tTG IgG in diagnosis of CD was low at 3% (6/178).

CONCLUSION

In this cohort of patients, the utility of isolated tTG IgG in diagnosing CD was low at 3%.

Simultaneous detection of IgA and IgG antibodies against tissue transglutaminase: The preferred pre-biopsy test in childhood celiac disease

OBJECTIVES

IgA antibodies against tissue transglutaminase (anti-TG2) is a reliable marker of celiac disease (CD). However, IgA-deficient patients are not identified and young children may lack IgA anti-TG2. Combined detection of IgA and IgG (IgA/IgG) against deamidated gliadin peptides (DGP) has shown a high diagnostic performance for untreated CD. Here we examined the utility of IgA/IgG anti-TG2, IgA/IgG anti-DGP and IgA/IgG against a mix of TG2 and DGP (anti-TG2/DGP) in finding CD among children.

METHODS

Serum antibodies against TG2, DGP, and TG2/DGP were determined with ELISA in 242 children referred to a paediatric gastroenterologist. Fifty had untreated CD verified by an intestinal biopsy and 192/242 children had other diseases than CD.

RESULTS

Forty-eight untreated CD children had increased IgA/IgG anti-TG2, 47/50 had increased IgA/IgG anti-DGP and 46/50 had increased IgA/IgG anti-TG2/DGP. One control subject had increased IgA/IgG anti-TG2 and IgA/IgG anti-TG2/DGP, whereas 7/192 control subjects had increased IgA/IgG anti-DGP. The IgA/IgG anti-TG2 assay had the best performance with a sensitivity of 96%, a specificity of 99.5% and the area under the ROC-curve was 0.996 (95% CI 0.992-1, p < 0.0001).

CONCLUSIONS

Detection of one antibody is not sufficient when screening for untreated CD among children due to cases of IgA deficiency. The inclusion of DGP antigens in the IgA/IgG combination assays seems to affect the sensitivity and specificity negatively, whereas detection of IgA/IgG anti-TG2 has the potential of finding most untreated CD patients, including those with IgA deficiency.

Decrease by 50% of plasma IgA tissue transglutaminase antibody concentrations within 2 months after start of gluten-free diet in children with celiac disease used as a confirming diagnostic test

BACKGROUND

Histological examination of small bowel biopsies is normally the gold standard for the diagnosis of celiac disease (CD). The objective of this study was to investigate whether the rate of decreases in elevated plasma IgA tissue transglutaminase antibody (IgA-tTG) and/or IgG deamidated gliadin peptides antibody (IgG - DGP) concentrations could be used as a confirming test for CD in children on a gluten-free diet (GFD) when biopsy was omitted in the diagnostic process.

METHODS

In this retrospective study we compared children (≤18 years old) with a CD-confirming biopsy (n = 16) to children without a biopsy (n = 18). After initiation of GFD the antibody half-life (the time (T½) when the antibody concentration is 50% decreased) was determined in all children.

RESULTS

Children with a biopsy (IgA-tTG, T½ = 1.9 months; IgG - DGP, T½ = 2.2 months) and children without a biopsy (IgA-tTG, T½ = 1.6 months; IgG - DGP, T½ = 2.7 months) had comparable T½ (mean) results (p < 0.05) supporting that all children had the CD diagnosis.

CONCLUSIONS

When biopsy was omitted a rapid rate of decrease in CD antibody concentrations confirmed the CD diagnosis in children on GFD. The half-lives (T½) of IgA-tTG were less than 2 months in CD children.

Young Age at Diagnosis of Type 1 Diabetes Is Associated with the Development of Celiac Disease-Associated Antibodies in Children Living in Newfoundland and Labrador, Canada

OBJECTIVES

The objectives of this study were to establish the prevalence of positive antibodies to endomysium (EMA) and tissue transglutaminase (tTG) in children with type 1 diabetes living in Newfoundland and Labrador (NL), and to examine clinical features associated with positive antibodies.

METHODS

Patients were recruited from the pediatric diabetes clinic. One hundred sixty-seven children with type 1 diabetes from the 280 children followed at the clinic were prospectively screened for celiac disease using EMA and tTG. The variables of Irish descent, age at onset of diabetes, duration of diabetes, sex, family history of celiac disease, hemoglobin A1C (A1C), ferritin, gastrointestinal symptoms, and body mass index were compiled for all patients. The group of patients with positive antibodies to EMA and/or tTG was compared to the group with negative antibodies.

RESULTS

The prevalence of patients with positive antibodies to EMA and/or tTG was 16.8% (n = 28). One patient had also been previously diagnosed with symptomatic celiac disease. The two statistically significant variables with positive antibodies were an earlier age at onset of diabetes (Mann-Whitney U two-tailed test: mean difference 3.2 years, 95% CI 1.7-4.8 years, p < 0.0001) and longer duration of diabetes (Mann-Whitney U two-tailed test: mean difference 2.9 years, 95% CI 1.3-4.4 years, p < 0.0001). Irish descent was associated with positive antibodies but did not reach statistical significance. On logistic regression analysis performed with these three variables together, only age at onset of diabetes remained significant.

CONCLUSIONS

There is a high prevalence of celiac disease-associated antibodies in children living in NL with type 1 diabetes. Unlike other clinical features, an earlier age at onset of diabetes was predictive for positive antibodies. As the majority of children with positive antibodies did not have signs or symptoms of celiac disease, routine screening for celiac disease in type 1 diabetes is recommended.

Silent coeliac disease is over-represented in children with type 1 diabetes and their siblings

AIM

This study measured autoantibodies against tissue transglutaminase (anti-tTG) to detect untreated coeliac disease in children with type 1 diabetes and their siblings.

METHODS

Anti-tTG was measured in prospectively collected sera from 169 children at the onset of diabetes, 88 of their siblings and 96 matched control children. Coeliac disease was confirmed with a small intestinal biopsy.

RESULTS

Coeliac disease was diagnosed in five children before diabetes onset. A further 12 children were diagnosed after diabetes onset, without any gastrointestinal symptoms, and 11 of these had anti-tTG at the onset of diabetes, with the remaining child showing seroconversion within 6 months. Hence, all the children with both diseases had anti-tTG at or before diabetes diagnosis, and the prevalence of coeliac disease was 10.1%. Moreover, 6.8% of the siblings and 3.1% of the control children had elevated levels of anti-tTG. None of the siblings reported any coeliac-related symptoms, despite being positive for anti-tTG, and coeliac disease has so far been biopsy confirmed in 4.5%.

CONCLUSION

Silent coeliac disease is over-represented in children with type 1 diabetes and their siblings. All diabetes children and their siblings should be tested and followed for the presence of anti-tTG and coeliac disease.

Internalizing the threat of risk--a qualitative study about adolescents' experience living with screening-detected celiac disease 5 years after diagnosis

BACKGROUND

Mass screening could identify those with unrecognized celiac disease (CD), but the experience of being detected through screening and living with screening-detected CD should be explored before considering this as acceptable intervention. For this study we invited screening-detected adolescents to describe their experience living with screening-detected CD five years after diagnosis with the aim to explore how their perceptions, practices, and beliefs evolved.

METHODS

Adolescents who were diagnosed through a population-based CD screening were invited to write narratives after being diagnosed. Of 153 adolescents who were eventually diagnosed through the screening, 91 wrote narratives one year after diagnosis and 72 five years after diagnosis. A qualitative content analysis resulted in a theme and categories that describe the experience living with screening-detected CD five years after diagnosis.

RESULTS

The overall theme--Internalizing the threat of risk--illustrates that being detected through screening and the internalized threat of future health complications have impacted how these adolescents felt about the diagnosis, coped with the gluten-free diet (GFD), and thought about CD screening. This theme is supported by four categories: maintaining an imposed disease identity describes how they continued to define their diagnosis in relation to the screening. They also expressed moving from forced food changes to adapted diet routines by describing habits, routines, coping strategies, and the financial burden of the GFD. They had enduring beliefs of being spared negative consequences, however, even after five years, some doubted they had CD and worried that being detected and eating a GFD might not be beneficial, i.e. continuing to fear it is "all in vain".

CONCLUSIONS

There was maintenance and evolution in the perceptions, practices, and beliefs of the adolescents after five years. Some have adjusted to the disease and adapted new habits and coping strategies to deal with the GFD, while others still doubt they have CD or that being detected was beneficial. The transition to adapting to the disease and GFD is ongoing, illustrating the importance of providing ongoing support for those with screening-detected CD as they adjust to this chronic disease and the GFD.

The clinical response to gluten challenge: a review of the literature

The aim of this review was to identify, evaluate and summarize all relevant studies reporting on the clinical response to gluten challenge by adult or pediatric patients with suspected or diagnosed coeliac disease (CD) on a gluten-free diet. We evaluated the effect of gluten challenge on changes in symptoms, intestinal mucosa histology, and serum antibodies. A systematic electronic search was performed for studies published as of 1966 using PubMed and Scopus databases. In the reviewed studies, doses ranged from 0.2 to 30 g/day of wheat gluten or comprised a gluten-containing diet. The onset of symptoms upon gluten intake varied largely from days to months and did not parallel serum antibody or histological changes. Within 3 months of gluten challenge, 70%-100% of pediatric CD patients became positive for AGA-IgA and EMA-IgA antibodies and 50%-70% for AGA-IgG. A limited number of trials suggest that no more than half of adult patients developed positive AGA-IgA, EMA-IgA, tTG-IgA or DGP-IgA/IgG titers. Approximately 50%-100% of pediatric and adult patients experienced mucosal relapse of gluten provocation within 3 months, which was preceded by increased mucosal intra-epithelial lymphocytes within several days of challenge. A 3-month high-dose gluten challenge should be suitable to diagnose the majority of CD patients. In some cases prolonged challenge may be needed to verify diagnosis. Combination testing for antibodies and mucosal histology may fasten the diagnosis.

Profile of typical and atypical celiac disease in Serbian children

We compared the clinical, biopsy and serology profile in typical vs atypical celiac disease. Mean TTG value for Marsh 3b/c in typical group was (140.53+/-88.77) and in atypical (140.66+/-73.53) (P=0.622). Seventy seven percent of patients had Marsh 3b/c in typical and 67.5% in atypical group (P=0.400).

Prevalence and sensitization of atopic allergy and coeliac disease in the Northern Sweden Population Health Study

Background

Atopic allergy is effected by a number of environmental exposures, such as dry air and time spent outdoors, but there are few estimates of the prevalence in populations from sub-arctic areas.

Objective

To determine the prevalence and severity of symptoms of food, inhalation and skin-related allergens and coeliac disease (CD) in the sub-arctic region of Sweden. To study the correlation between self-reported allergy and allergy test results. To estimate the heritability of these estimates.

Study design

The study was conducted in Karesuando and Soppero in Northern Sweden as part of the Northern Sweden Population Health Study (n=1,068). We used a questionnaire for self-reported allergy and CD status and measured inhalation-related allergens using Phadiatop, food-related allergens using the F×5 assay and IgA and IgG antibodies against tissue transglutaminase (anti-tTG) to indicate prevalence of CD.

Results

The prevalence of self-reported allergy was very high, with 42.3% reporting mild to severe allergy. Inhalation-related allergy was reported in 26.7%, food-related allergy in 24.9% and skin-related allergy in 2.4% of the participants. Of inhalation-related allergy, 11.0% reported reactions against fur and 14.6% against pollen/grass. Among food-related reactions, 14.9% reported milk (protein and lactose) as the cause. The IgE measurements showed that 18.4% had elevated values for inhalation allergens and 11.7% for food allergens. Self-reported allergies and symptoms were positively correlated (p<0.01) with age- and sex-corrected inhalation allergens. Allergy prevalence was inversely correlated with age and number of hours spent outdoors. High levels of IgA and IgG anti-tTG antibodies, CD-related allergens, were found in 1.4 and 0.6% of participants, respectively. All allergens were found to be significantly (p<3 e–10) heritable, with estimated heritabilities ranging from 0.34 (F×5) to 0.65 (IgA).

Conclusions

Self-reported allergy correlated well with the antibody measurements. The prevalence of allergy was highest in the young and those working inside. Heritability of atopy and sensitization was high. The prevalence of CD-related autoantibodies was high and did not coincide with the self-reported allergy.

Correlation between IgA tissue transglutaminase antibody ratio and histological finding in celiac disease

OBJECTIVES

Positivity of both immunoglobulin A anti-tissue transglutaminase (TTG) and anti-endomysium antibodies (EMA) has a positive predictive value of nearly 100% for celiac disease (CD). The objective of the present study was to evaluate whether patients of any age, with high pretest probability of CD and high titre of anti-TTG and EMA positivity, have a high probability of intestinal damage and may not require the biopsy for final diagnosis.

METHODS

A retrospective analysis of 412 consecutively referred patients, age range 10 months to 72 years, who underwent small-bowel biopsy for suspicion of CD and positivity to both anti-TTG and EMA, was performed at 4 Italian centers. Biopsies were evaluated independently by 2 pathologists using Marsh modified classification; in cases of dissimilar results, a third pathologist examined the biopsy. The final histological finding diagnosis was expressed as the prevalent or highest score assigned by the pathologist board.

RESULTS

Three hundred ninety-six patients (96.1%) had histological findings consistent with CD (grade 2 and 3a, 3b, or 3c of modified Marsh classification). An anti-TTG ratio ≥ 7 was able to identify with the 3 assays used (Celikey, anti-TTG immunoglobulin A, EuTTG) all of the patients with significant mucosal damage (Marsh ≥ 2) independent of age and sex; specificity and positive predictive value were 100%. An anti-TTG ratio >20 was more specific (99.8%) for identification of patients with villous atrophy (Marsh 3 a, b, or c).

CONCLUSIONS

Patients with positivity of anti-TTG ≥ 7-fold cutoff, confirmed by positivity to EMA, have a high-degree probability of duodenal damage. In selected conditions, a duodenal biopsy may be avoided and a confirmed greatly positive anti-TTG result could be the basis to prescribe a gluten-free diet.

Additional value of serum I-FABP levels for evaluating celiac disease activity in children

OBJECTIVES

Addition of a non-invasive marker for intestinal damage to the currently used parameters for celiac disease activity (symptoms, serologic tests and biopsy) might further improve clinical management of celiac disease (CD). Intestinal fatty acid binding protein (I-FABP) is a cytosolic enterocyte protein and sensitive marker for enterocyte damage in the small intestine. We investigated whether serum I-FABP levels can reliably identify villous atrophy in children with a positive CD antibody screening. Moreover, the recovery of I-FABP levels after gluten free diet (GFD) was studied.

METHODS

I-FABP levels were analyzed retrospectively in 49 children with biopsy proven CD and in 19 patients with a positive screening but without histological confirmation of CD. Blood was collected before biopsy and repeatedly after the onset of GFD.

RESULTS

Initial I-FABP concentrations in CD (median 458 pg/ml) were significantly (p < 0.001) elevated compared to controls (median 20 pg/ml). In the control group, only two of 19 children were found to have elevated I-FABP levels, of which one was subsequently diagnosed with CD after gluten challenge. I-FABP concentrations correlated with severity of villous atrophy. In all CD patients, I-FABP levels decreased quickly after GFD and normalized in 80% of patients within 12 weeks.

CONCLUSIONS

Elevated I-FABP levels accurately predict villous atrophy in children with a positive serologic test for CD (positive predictive value 98%). In addition, measurement of I-FABP enables monitoring the response to GFD.

Specific celiac disease antibodies in children on a gluten-free diet

OBJECTIVE

Celiac disease (CD) is characterized by histologic alterations in small bowel biopsies. Circulating specific CD antibodies at the time of diagnosis and their disappearance after a gluten-free diet support the diagnosis of CD. We aimed to determine the behavior of the CD antibodies immunoglobulin A anti-tissue transglutaminase (anti-TG2) and immunoglobulin A endomysium (EMA) in children with CD after starting a gluten-free diet.

METHODS

This was a retrospective multicenter study in the Netherlands between 2001 and 2009. Inclusion criteria were all newly diagnosed patients with CD younger than 19 years who had at least 1 anti-TG2 and/or EMA measurement before and after starting a gluten-free diet. Eight different anti-TG2 kits were used with substrates of guinea pig TG2 in 1 (Sigma) and 7 human-recombinant TG2: Varelisa and EliA Celikey Phadia-GmbH; Orgentec Diagnostica-GmbH; Diarect AG; Roboscreen GmbH; Aeskulisa Diagnostics; Binding Site Ltd. EMA was analyzed with indirect immunofluorescence tests. Statistical analyses were performed by using mixed-model repeated measurements and survival analysis.

RESULTS

There were 129 children with CD included (mean age: 5.6 years; SD ± 4.2). The mean concentration of anti-TG2 decreased significantly within 3 months after starting a gluten-free diet (P < .0001). The cumulative percentage of children who became negative for EMA after ½, 1, 1½, and 2 years was 31%, 60%, 74%, and 87%, respectively. For anti-TG2, a comparable trend was shown: 35%, 55%, 64%, and 78%, respectively.

CONCLUSIONS

Doctors taking care of children with CD should be aware that the mean concentration of anti-TG2 will show a 74% decrease (95% confidence interval: 69%-79%) after 3 months of gluten-free diet, and ∼80% of the children will be sero-negative for EMA and anti-TG2 after 2 years of the diet.

Clinical accuracy of anti-tissue transglutaminase as screening test for celiac disease under 2 years

AIM

To investigate, in patients with suspected celiac disease (CD) younger than 2 years, the clinical value of anti-tissue transglutaminase (tTG) in diagnostic work-up of CD.

METHODS

Between June 2005 and June 2009, 169 patients aged <2 years, with symptoms suggestive of CD, were submitted to biopsy. CD diagnosis was based on the revised criteria of the European Society for Pediatric Gastroenterology, Hepatology and Nutrition.

RESULTS

Of the 169 patients enrolled, 155 were included: 108 of them showed mucosal atrophy and 47 negative histology. Sensitivity and specificity of tTG, at the cut-off of 8 AU/mL, were 0.96 (CI 0.91-0.99) and 0.91 (CI 0.80-0.98), respectively, with likelihood ratio (LR) of 11.31; at the cut-off of 16 AU/mL, they were 0.79 (CI 0.70-0.86) and 1.00, respectively (CI 0.92-1.00), with LR 4.50.

CONCLUSIONS

In patients younger than 2 years, suspected for CD, tTG is very valuable in selecting for small intestinal biopsy.

Celiac disease in children and adolescents at a singe center in Saudi Arabia

BACKGROUND AND OBJECTIVES

Celiac disease (CD) is an immune-mediated enteropathy, induced by gluten in genetically susceptible individuals. The objective of this study was to describe the clinical pattern of CD in children from the western region of Saudi Arabia.

DESIGN AND SETTING

Retrospective, hospital-based.

PATIENTS AND METHODS

This study included children with a biopsy-proven diagnosis of CD made between September 2002 and July 2007. Children were admitted to the endoscopy unit for a small-bowel biopsy if they had gastrointestinal symptoms suggestive of CD or if they were positive for a CD-antibody screen performed for the high-risk groups.

RESULTS

Eighty children were identified with a diagnosis of CD. Their mean (SD) age was 9.6 (4.9) years (range, 0.5-18 years). There were 44 (55%) female patients. Forty-one (51%) patients were detected during screening of high-risk groups, while 39 (49%) patients had classical symptoms of malabsorption. The screening also detected asymptomatic patients. Of 65 patients tested, 11 (17%) had elevated liver function tests, which reverted to normal after introduction of a gluten-free diet (GFD) except in one case. Seventy-three (91%) patients were positive for anti-tissue transglutaminase antibodies, 18 (23%), for IgG anti-gliadin antibodies; and 46 (58%), for IgA anti-gliadin antibodies. Forty-one (56%) patients showed good adherence to GFD as assessed by dietary history and the decline in anti-tTG level.

CONCLUSION

CD may present with classical symptoms or be identified through screening programs. Growth and laboratory abnormalities usually improve after introduction of a GFD. Adherence to a GFD remains a problem; therefore, thorough assessment and counseling at the time of diagnosis and ongoing care are crucial.

How do children experience participating in a coeliac disease screening? A qualitative study based on children’s written narratives

Aim: To explore how 12-year-old Swedish children experienced being involved in a coeliac disease (CD) screening. Methods: A qualitative approach was used to analyse short narratives written by children who had taken part in a school-based CD screening. Narratives were written after blood sampling, but prior to learning of the test results. Through an oscillation between the texts, codes, subcategories and four categories, a theme was generated describing the children’s experience. Results: The theme ‘‘A Journey towards Confidence’’ captures the overall experience of the screening. It illustrates that, although some children faced fear or anxiety, overall they had or were provided tools allowing them to cope well and experience a journey towards confidence. The categories describe conditions that contributed to the experience. The first, being involved, reflects the importance of involvement in receiving information and deciding to participate. Being a ‘‘good citizen’’ refers to feeling a duty to help and a trust to be treated fairly. Being able to cope with the screening was influenced by the children’s ability to manage sensations and support received. The last category, being able to balance risk, illustrates that the children were able to balance the risks of screening when they had a realistic understanding of the disease and their vulnerability and had tamed their anxiety. Conclusions: This study increases the understanding of how 12-year-old Swedish children experienced participating in a CD screening and describes conditions important for a positive experience. We show that, although some children faced anxiety, they had, or were provided with, tools allowing them to cope well and gain confidence.

High density of intraepithelial gammadelta lymphocytes and deposits of immunoglobulin (Ig)M anti-tissue transglutaminase antibodies in the jejunum of coeliac patients with IgA deficiency

The diagnosis of coeliac disease (CD) represents a special challenge in selective immunoglobulin (Ig)A deficiency (IgAD). A high density of T cell receptor (TCR)gammadelta(+) intraepithelial lymphocytes (IELs) and intestinal IgA anti-tissue transglutaminase 2 (anti-TG2) antibody deposits are suggestive of CD. We analysed the density of TCRgammadelta(+) IELs and the deposition of IgM anti-TG2 antibodies in the jejunal mucosa of IgAD patients with and without CD. Immunohistochemical analyses for the number of CD3+ and TCRgammadelta(+) IELs and double immunofluorescence assay for IgM anti-TG2 antibody deposits were performed in biopsies from 25 children with IgAD (nine untreated CD, seven potential CD and nine without CD). Sixteen immunologically intact children without CD represented the controls. IgAD without CD had a higher number of CD3+ and TCRgammadelta(+) IELs than controls (P < 0.05), but lower than IgAD with CD (P < 0.01). No significant differences were noted between IgAD subjects without CD and those with potential CD. Furthermore, IgAD patients without CD showed a higher TCRgammadelta(+)/CD3+ ratio than the control group (P < 0.05), while the ratio was similar to subjects with CD and potential CD. Intestinal IgM anti-TG2 antibody deposits were present in six of seven of the IgAD patients with untreated CD, one of seven with potential CD and none of those without CD. Most of the patients with IgAD show immune activation in the jejunal mucosa. IgM anti-TG2 antibody deposits are present only in CD. Intestinal IgM anti-TG2 and immunohistochemical markers do not discriminate between IgAD and potential CD with IgAD. Therefore, the serum IgG CD-associated autoantibodies remains very important for the diagnosis of CD in IgAD.

Anthropometric, serologic, and laboratory correlation with villous blunting in pediatric celiac disease: diabetics are different

OBJECTIVES

We evaluated the correlation between level of tissue transglutaminase (TTG) and endomysial antibodies (EMAs) to different degrees of intestinal damage in celiac disease (CD) children with [presence of diabetes mellitus (DM)+] and without [absence of diabetes mellitus (DM-)] type I diabetes. We also assessed the correlation between albumin, hemoglobin (hgb), transaminases, symptom presence, age of cereal introduction, and body mass index (BMI) to different degrees of intestinal damage.

METHODS

Retrospective review of patients seen at the Children's Hospital of Philadelphia between January 2002 and June 2006 revealed 60 children (mean age 9.8 y) who had TTG, EMA, and other laboratory tests performed at time of histologic CD diagnosis from duodenal biopsies. Twenty-one of 60 children had DM. All children were stratified for histologic damage according to Marsh classification.

RESULTS

Overall, Marsh (M) I lesions were seen in 2 (3.3%), MII in 2 (3.3%), IIIa in 14 (23.3%), IIIb in 15 (25%), and IIIc in 27 (45%); no differences in DM- versus DM+ groups. TTG was positive in all and EMA was positive in all but 1 child. Among DM- and DM+ children, median TTG and EMA values were higher with MIIIa-c, respectively. For DM-, BMI percentile, hgb, and mean corpuscular volume were lower with advancing histology. However, in DM+, no significant correlation of BMI percentile, hgb, or mean corpuscular volume with grade was observed. Cereal introduction age, hypoalbuminemia, and hepatitis did not differ between MIIIa-c in any group.

CONCLUSIONS

TTG and EMA mean serum values are higher in CD children with severe enteropathy (MIIIc) than in those with mild enteropathy (MIIIa). CD in DM is accompanied by serologic and histologic findings identical to that of a non-DM CD population. As CD is identified through screening in DM, it is often silent and not associated with symptoms, growth abnormalities, or anemia. Clinical parameters (height, weight, hgb, symptoms) are not helpful in identifying silent CD in DM.

Two-year follow-up of anti-transglutaminase autoantibodies among celiac children on gluten-free diet: Comparison of IgG and IgA

OBJECTIVES

To investigate the evolution of IgA and IgG autoantibodies against tissue transglutaminase (tTGase) in celiac patients on gluten-free diet (GFD).

METHODS

IgA and IgG anti-tTGAse autoantibodies was evaluated in 93 patients (58 girls and 35 boys; mean age 3.56 +/- 3.04 years; range 0.94-17.5 years) at diagnosis of celiac disease and after 1, 2, 4, 6, 12, 18, 24 months of follow-up on GFD. Autoantibodies were measured with a radioassay using in vitro transcribed-translated human recombinant tTGAse, and immune complexes were precipitated with protein A- or anti-IgA-agarose for IgG and IgA, respectively.

RESULTS

Autoantibody titers started to decline very soon after removal of gluten, and no significant differences in the decrease rate between IgG and IgA antibodies were observed. After 6 months on GFD, 63 and 49% of the patients were negative for IgG and IgA, respectively. Patients who remained autoantibody-positive after 6 months of treatment initially presented with significantly higher titers at the time of diagnosis compared to patients that had lost their antibodies by that time. Children diagnosed before the age of two years presented lower autoantibody titers, while patients positive for HLA-DR7 had higher anti-tTGase levels, especially IgA.

CONCLUSIONS

There are no differences in the performance of IgG and IgA class autoantibodies in the evolution of celiac patients. Between 3 and 6 months on GFD, almost half of the patients are negative for anti-tTGase antibodies. In our experience, they can be of help in evaluating compliance with diet, at least during the first two years of treatment.

Antibodies against synthetic deamidated gliadin peptides for celiac disease diagnosis and follow-up in children

BACKGROUND

AGA IgA II and AGA IgG II have recently been suggested as reliable tools for celiac disease (CD) diagnosis. We compared their utility for diagnosis and monitoring CD in children with that of tTG IgA, an established CD marker.

METHODS

We studied a cohort of 161 CD and 129 control children in whom CD was histologically confirmed or ruled out. We followed 37 children with CD on a gluten-free diet for 12-84 months. In fasting sera, we measured AGA IgA II, AGA IgG II, and tTG IgA using ELISAs.

RESULTS

The best sensitivity (92.5%), specificity (97.6%), positive predictive value (98%), and negative predictive value (91.2%) were obtained using tTG IgA. AGA IgG II correctly identified 3 of 3 children with CD with total IgA deficiency who had negative AGA IgA II and tTG IgA results. In children <2 years old without total IgA deficiency, AGA IgG II and tTG IgA performed equally well (sensitivity 96.4% and specificity 100%). AGA IgA II, AGA IgG II, and tTG IgA concentrations diminished significantly (P < 0.0001) after 1 year of a gluten-free diet, reaching values below the cutoff in 87%, 70%, and 51% of cases, respectively.

CONCLUSIONS

The best available index for diagnosing CD in children was tTG IgA. In infants <2 years old, AGA IgG II performed as well as tTG IgA in cases without total IgA deficiency and allowed detection of CD when total IgA was <0.06 g/L. Gluten-free diet monitoring can be achieved using any of the studied serum markers.

Antigliadin immunoglobulin A best in finding celiac disease in children younger than 18 months of age

OBJECTIVES

The aim was to investigate age-dependent serum levels and occurrence of elevated celiac disease (CD)-related antibodies in young children, to define the optimal serological procedure when selecting for small intestinal biopsy.

PATIENTS AND METHODS

Included were 428 children with biopsy verified CD (median age 16 months; range 7.5 months-14 years) and 216 controls (median age 2.7 years; range 8.5 months-14.6 years). Immunoglobulin (Ig) A antibodies against gliadin (AGA-IgA), tissue transglutaminase (tTG-IgA), and endomysium (EMA-IgA) were analysed.

RESULTS

Increased serum AGA-IgA levels were found in 411 of 428 CD cases, tTG-IgA in 385 of 428, and EMA-IgA in 383 of 428. In the control group, 11 of 216 had increased levels of AGA-IgA, 5 of 216 of tTG-IgA, and 8 of 216 of EMA-IgA. In CD children younger than 18 months, elevated AGA-IgA occurred in 97% and elevated tTG-IgA and EMA-IgA were found in 83% of the cases. Conversely, in CD children older than 18 months, elevated AGA-IgA occurred in 94%, and elevated tTG-IgA and EMA-IgA were found in 99% of the cases.

CONCLUSIONS

In children older than 18 months, both tTG-IgA and EMA-IgA are sufficiently accurate to be used as a single antibody marker, whereas a large proportion of younger children with CD lack these antibodies. Therefore, when selecting children for small intestinal biopsy, the detection of a combination of AGA-IgA and tTG-IgA is optimal for identifying untreated CD in children younger than 18 months.

Strongly positive tissue transglutaminase antibodies are associated with Marsh 3 histopathology in adult and pediatric celiac disease

GOALS

Our objective was to determine whether high serologic IgA tissue transglutaminase antibodies (TTGA) are exclusively associated with celiac disease (CD).

BACKGROUND

IgA TTGA are found in the serum of most individuals with CD. This serologic marker is used to screen individuals with suspected CD for duodenal biopsy, the gold standard of CD diagnosis. Data suggest strongly positive IgA TTGA >or= 100 units are highly specific for CD histopathology in pediatric patients and may be sufficient for diagnosis.

STUDY

Records of adult and pediatric subjects in the celiac study at the University of Utah and University of California Irvine were reviewed for strongly positive TTGA. Pathology reports from duodenal biopsies of subjects with IgA TTGA >or= 100 units were graded as 0 to 3 by modified Marsh criteria.

RESULTS

From a pool of 1882 subjects with IgA TTGA assayed, 208 had IgA TTGA >or= 100 units. Seventy-six of these, including 28 children and 48 adults, also had duodenal biopsies. Villous atrophy (Marsh 3 histopathology) was found on biopsy in 73 (96%) of these subjects. The remaining 3 subjects had intermediate Marsh histology. One (Marsh 1) had a complete serologic response to a gluten-free diet and 2 had Marsh 2 lesions and positive endomysium, making early CD most likely.

CONCLUSIONS

IgA TTGA >or= 100 units occur almost exclusively in the setting of Marsh 3 duodenal histopathology in adults and children. Rare cases without villous atrophy were marked by intermediate Marsh changes suggestive of early CD. IgA TTGA >or= 100 arbitrary units indicate duodenal changes consistent with CD.

Antibodies against synthetic deamidated gliadin peptides and tissue transglutaminase for the identification of childhood celiac disease

BACKGROUND & AIMS

Children with celiac disease have antibodies against gliadin, tissue transglutaminase (tTG), or both antigens. The aim was to evaluate immunoglobulin (Ig)A and IgG antibodies to synthetic deamidated gliadin peptides (DGP) and human tTG as screening markers for childhood celiac disease.

METHODS

Antibodies were detected in enzyme-linked immunosorbent assay using anti-human IgA, IgG, or a combined conjugate of IgA and IgG (IgAG) against DGP, tTG, or both (DGP/tTG), in sera from 119 children with celiac disease, 57 disease controls, and 398 blood donors. Treatment with a gluten-free diet was evaluated in 20 children with celiac disease who were followed up for 6 months from diagnosis.

RESULTS

The highest sensitivity was accounted for IgAG-DGP/tTG at 100% (119 of 119), followed by IgA-tTG at 97% (115 of 119), IgG-DGP at 95% (113 of 119), IgA-DGP at 91% (108 of 119), and IgG-tTG at 13% (15 of 119). With respect to disease controls and blood donors, specificity was for IgAG-DGP/tTG at 89% (51 of 57) and at 97% (385 of 398), IgA-tTG at 96% (55 of 57) and at 98% (392 of 398), IgG-DGP at 86% (49 of 57) and at 99% (395 of 398), IgA-DGP at 91% (52 of 57) and at 92% (366 of 398), and IgG-tTG at 100%, respectively. The concordances between antibody assays were 87%-98%, except for comparisons with IgG-tTG (39%-41%). After 6 months of a gluten-free diet, the mean antibody levels decreased for all test results (P < .001).

CONCLUSIONS

The combined IgAG-DGP/tTG assay is recommended as a front-line screening test for the identification of childhood celiac disease and also could be used as a marker of dietary compliance.

Increased prevalence of silent celiac disease among Greek epileptic children

Celiac disease is an immune-mediated enteropathy triggered by the ingestion of gluten in genetically susceptible individuals. Many reports mention the association between epilepsy and celiac disease and the occasional presence of occipital corticosubcortical calcifications. We investigated 255 children with idiopathic epilepsy. Evaluation included use of routine, easily obtainable studies. Patients were screened for immunoglobulin A (IgA), immunoglobulin G (IgG) antigliadin antibodies and immunoglobulin A antitissue transglutaminase antibodies. Moreover, presence of IgA antiendomysial and antireticulin antibodies was screened. Patients with positive IgA antigliadin antibodies underwent a small intestinal biopsy. Controls consisted of 280 healthy children. Intestinal histopathologic changes, positive IgA antigliadin antibodies or IgG antigliadin antibodies, antireticulin antibodies, and antitissue transglutaminase IgA antibodies were found in five epileptic children but not in control subjects (P = 0.0241). Intracranial calcifications were not found in epileptic children with celiac disease. The findings indicate that prevalence of silent celiac disease is increased among children with idiopathic epilepsy; the type of epilepsy does not appear to play a role. Serum antitissue transglutaminase IgA antibodies could be a good marker for celiac disease screening. Occipital corticosubcortical calcifications are rarer in children with celiac disease and epilepsy.

Clinical value of immunoglobulin A antitransglutaminase assay in the diagnosis of celiac disease

OBJECTIVES

Our goal was to evaluate the possible correspondence between antitissue transglutaminase of immunoglobulin A class levels and stage of mucosal damage in patients affected by celiac disease. In addition, we assessed clinical use of antitissue transglutaminase values to predict biopsy results.

METHODS

One thousand eight hundred eighty-six consecutive patients with symptoms suggestive of celiac disease and 305 healthy controls underwent determination of serum levels of immunoglobulin A and antitissue transglutaminase. An intestinal biopsy was performed in subjects with antitissue transglutaminase levels > or = 4 IU/mL and in subjects with negative antitissue transglutaminase levels but with clinical suspicion of celiac disease. Histologic grading of celiac disease was consistent with the Marsh classification.

RESULTS

One hundred eighty-six subjects with positive antitissue transglutaminase levels and 91 patients with negative antitissue transglutaminase levels were submitted to biopsy. In all healthy subjects, antitissue transglutaminase results were negative. Histologic evaluations in patients with positive antitissue transglutaminase levels gave the following results: type 0 in 25 patients, type 1 in 3 patients, type 2 in 4 patients, type 3a in 22 patients, type 3b in 74 patients, and type 3c in 58 patients. None of the patients with negative antitissue transglutaminase levels showed histologic findings suggestive of celiac disease. The mean antitissue transglutaminase values in patients without mucosal atrophy were significantly lower than in patients with mucosal atrophy. Antitissue transglutaminase values > or = 20 IU/mL were found in only 1 patient without mucosal atrophy.

CONCLUSIONS

Our study found a strong correspondence between antitissue transglutaminase levels and stage of mucosal injury; antitissue transglutaminase values > 20 IU/mL seemed to be strongly predictive of mucosal atrophy.

A new indirect chemiluminescent immunoassay to measure anti-tissue transglutaminase antibodies

OBJECTIVES

Anti-tissue transglutaminase antibody (anti-tTG) determination using second-generation (human antigen) enzyme-linked immunoassays (ELISAs) is a very accurate test to diagnose celiac disease (CD). In this study, we compared 2 second-generation ELISAs (Celikey tTG; Pharmacia Diagnostics GmbH & Co, Freiburg, Germany, and QuantaLite; Inova Diagnostics, San Diego, CA) and antiendomysial antibodies (EMAs) with a new indirect chemiluminescence immunoassay (LIAISON tTG; DiaSorin S.p.A., Saluggia, Italy) in diagnosing and monitoring CD in children.

PATIENTS AND METHODS

Antiendomysial antibodies, anti-tTGs and total immunoglobulin A were measured in the sera of 103 control children, 101 children with histologically proven CD and 31 CD children on gluten-free diet (GFD).

RESULTS

Anti-tissue transglutaminase antibody mean levels were significantly higher in CD with respect to control or GFD children. The sensitivity value of EMAs, LIAISON tTG, Celikey tTG and QuantaLite in diagnosing CD was 97.7%, 97.0%, 94.1% and 98.0%, respectively, and the corresponding specificity values were 91.1%, 98.1%, 97.1% and 96.1%, respectively. The degree of mucosal destruction (Marsh criteria) was correlated with EMA semiquantification (P < 0.01) and with the circulating levels of anti-tTGs measured using LIAISON (P < 0.05) or QuantaLite (P < 0.01). Twenty-six CD children were followed up from 5 to 25 months after GFD. The circulating levels of anti-tTGs measured with any of the 3 assays significantly dropped after GFD.

CONCLUSIONS

Anti-tissue transglutaminase antibody determination with second-generation ELISAs is as effective as EMAs for CD diagnosis. The novel chemiluminescent method described in the present paper for the detection of anti-tTGs in the diagnosis of CD had the highest sensitivity and specificity values. The anti-tTG test correlates with the degree of mucosal destruction and is suitable for verifying patient compliance to dietary treatment.

Reduction of tissue transglutaminase autoantibody levels by gluten-free diet is associated with changes in subsets of peripheral blood lymphocytes in children with newly diagnosed coeliac disease

Tissue transglutaminase (tTG) autoantibodies decline after gluten-free diet in patients with coeliac disease. We tested the hypothesis that gluten-free diet-induced change in tTG autoantibody levels affects subsets of peripheral blood lymphocytes. Peripheral blood was obtained from 20 children with biopsy-proven active coeliac disease. Gluten-free diet was initiated and the children examined again after three and six months. tTG autoantibodies were measured in radioligand binding assays and lymphocyte subsets by flow cytometry. IgA-tTG levels at diagnosis, 2204 U/ml (median, range 113-24990), were reduced over six months to 76 U/ml (median, range 1-1261) (P < 0.001). At six months, 12/20 (60%) children had reduced their IgA-tTG levels to < 100 U/ml and these children showed a decrease in B cells (mean change -3.8%, P = 0.014), CD4+ T cells (mean -4.32%, P = 0.011) and CD4+ T cells expressing CD25high (mean change -0.62%, P = 0.036). In contrast, the CD4+CD25(high)CCR4+ T cell population increased during the same period (mean change 11.5%, P = 0.0036). The decline in IgA-tTG levels correlated to the decrease in B cells (r = 0.56, P = 0.01), CD4+ T cells (r = 0.66, P = 0.004) as well as CD4+CD25high T cells (r = 0.59, P = 0.01). A negative correlation was found between the decline in IgA-tTG and CD4+CD25high T cells expressing CD45RO (r = -0.49, P = 0.03) and CCR4 (r = -0.54, P = 0.01). This is the first observational study on the effect of gluten-free diet on concurrent changes of tTG autoantibodies and specific peripheral blood lymphocyte subsets. Our data suggest that flow cytometry may be a useful complement to tTG autoantibodies when studying the effects of gluten-free diet in children with coeliac disease.

Performance of antibodies against tissue transglutaminase for the diagnosis of celiac disease: meta-analysis

A meta-analysis of studies investigating the diagnostic accuracy of enzyme-linked immunosorbent assays (ELISA) for antibodies against tissue transglutaminases (tTG) of various origins in celiac disease (CD) diagnosis was carried out. Twenty-one studies, with untreated CD patients and healthy/CD-free controls, were included in the meta-analysis. The diagnostic accuracy was estimated using a summary receiver operating characteristic (SROC) curve and pooled sensitivity (Se) and specificity (Sp). Multiple assays within a study were treated by considering all the assays within a study and by analyzing the most popular assay (i.e., the commercial anti-tTTG ELISA most frequently utilized in the papers in which multiple assays were included). The SROC curve indicated the absence of heterogeneity, and the superiority of recombinant human tTG (rh-tTG) and purified human tTG (ph-tTG) compared to guinea pig-tTG (gp-tTG). The sensitivities (most popular assay) for rh-tTG, ph-tTG, and gp-tTG were 94%, 90%, and 92%, respectively, and the specificities were 97%, 92%, and 96%, respectively. A sensitivity analysis (exclusion of studies with bias) altered the results of ph-tTG: Se, 95%; Sp, 98%. The sensitivities (all individual assays) for rh-tTG, ph-tTG, and gp-tTG were 94%, 94%, and 91%, respectively, and the specificities were 95%, 94%, and 89%, respectively. Human tTG ELISA is sensitive and specific, and it can be used for mass screening. Sensitivity analysis showed that ph-tTG might perform better.

Outcome of infants with celiac disease

AIMS

Determine the proportion of infants whose celiac disease (CD) was confirmed in childhood and evaluate their prognosis in adulthood.

PATIENTS AND METHODS

The diagnosis of CD was established between 1971 and 1982 in 84 infants based on intestinal biopsy data; a gluten-free diet was prescribed and the cohort followed prospectively.

RESULTS

Thirty-six infants were followed less than 5 years. A second biopsy was performed in 25. Mucosa had healed in 13 and remained atrophic in 12. Three children developed partial villous atrophy between 6 and 12 years of age in spite of the gluten-free diet. Forty-five patients underwent a gluten challenge between 5 and 10 years of age: in 41 histological lesions relapsed, in two mucosa remained normal and clinical and immunological relapse developed in two. Among those 45 patients, 18 were examined after 18 years follow-up: the exclusion diet was resumed in four, overt clinical relapse developed in four and four experienced intermittent gastrointestinal disorders. All biopsies performed during a period of normal diet showed villous atrophy (except in one patient) without correlation with clinical symptoms.

CONCLUSION

The diagnosis of celiac disease in infants was confirmed in nearly all cases in childhood. When they reached adulthood, these patients had few symptoms but their histological lesions persisted. These data are in favor of a lifelong exclusion diet.

Successful treatment of epilepsy and celiac disease with a gluten-free diet

Celiac disease is a gluten-sensitive enteropathy, which recently has been described in association with epilepsy or other neurologic disturbances. This study describes a case of a 7-year-old female with intractable-to-treatment epilepsy and late-onset celiac disease, who was treated successfully with a gluten-free diet plus antiepileptic therapy. It is important for children with intractable cases of epilepsy and weight loss to undergo screening for celiac disease.

Natural history of transglutaminase autoantibodies and mucosal changes in children carrying HLA-conferred celiac disease susceptibility

OBJECTIVE

The natural history of the appearance and fate of transglutaminase autoantibodies (TGAs) and mucosal changes in children carrying HLA-conferred celiac disease (CD) risk remains obscure. The aim of this study was to investigate the sequence of events leading to overt CD by retrospective analysis of TGA values in serum samples collected frequently from genetically susceptible children since birth or early childhood.

MATERIAL AND METHODS

A total of 1101 at-risk children were recruited in the study. A duodenal biopsy was recommended to all TGA-positive children and performed if parental consent was obtained.

RESULTS

During up to 8 years of follow-up, 35 of the cohort children developed TGAs, the youngest at age 1.3 years. After age 1.3 years the annual TGA seroconversion rate was constantly around 1% at least until age 6 years. However, 18 of the 35 TGA-positive children (51%) lost TGAs, without any dietary manipulation. A further 7 children were IgA deficient; of these children, 2 developed IgG antigliadin antibodies (IgG-AGA). Only 13 of the 21 children (62%) who had duodenal biopsies had villous atrophy. The time that passed since emergence of TGAs failed to predict the biopsy findings. Only one of the children with TGAs and both of the IgA-deficient children with IgG-AGA had noticeable abdominal symptoms.

CONCLUSIONS

TGAs appear in children at a constant rate after 1 year of age until at least the age of 6 years. Over half of the children loose TGA without gluten exclusion, challenging TGA positivity-based CD prevalence estimates. In symptom-free children, a requirement of two consecutive TGA-positive samples taken >or=3 months apart before performing a duodenal biopsy might diminish the number of unnecessary intestinal biopsies.

Autoantibodies against soluble and immobilized human recombinant tissue transglutaminase in children with celiac disease

OBJECTIVES

The conformation of tissue transglutaminase might influence the performance of immunoassays to detect autoantibodies from patients with celiac disease. The present study investigated how the exposure of tissue transglutaminase kept in a liquid phase and fixed to a solid support affected the binding of immunoglobulin (Ig)A and IgG autoantibodies in children with untreated and treated celiac disease.

METHODS

Included were 73 untreated celiac disease children, 50 controls and 80 children with treated celiac disease. IgA and IgG antitissue transglutaminase were measured with solid phase enzyme-linked immunoassay (ELISA) and liquid phase radioligand binding assays. For IgG antitissue transglutaminase detection with radioligand binding assays antihuman IgG and protein A were used. IgA endomysial autoantibodies were measured by indirect immunofluorescence.

RESULTS

Both ELISA and radioligand binding assays detected IgA antitissue transglutaminase in 65 of 73 untreated celiac disease children and in 2 of 50 controls. One additional control child was detected with radioligand binding assays. Endomysial autoantibodies were present in 62 of 73 celiac disease children and in 2 of 50 controls. IgG antitissue transglutaminase was detected with both ELISA and radioligand binding assays in 40 of 73 untreated celiac disease children and in 2 of 50 controls. Radioligand binding assays using protein A detected 20 of 73 additional untreated celiac disease children and one control child with increased IgG antitissue transglutaminase. In treated celiac disease children, 21 of 80 were IgA antitissue transglutaminase positive with radioligand binding assays, 3 of 80 with ELISA, whereas none had endomysial autoantibodies.

CONCLUSIONS

No qualitative differences between radioligand binding assays and ELISA in IgA or IgG antitissue transglutaminase binding from untreated celiac disease children was demonstrated. However, discrepancies in the binding of IgA antitissue transglutaminase from a subgroup of treated celiac disease children indicated that alterations of tissue transglutaminase might occur on fixation of the antigen. Protein A used for radioligand binding assays seemed not to assess IgG autoantibodies exclusively. IgA antitissue transglutaminase detection in screening of childhood celiac disease can be performed either by ELISA or radioligand binding assays because the two assays are interchangeable.

Calcium activation of tissue transglutaminase in radioligand binding and enzyme-linked autoantibody immunoassays in childhood celiac disease

BACKGROUND

Conflicting data have been published concerning the effect of calcium on binding of autoantibodies to tissue transglutaminase (tTG) in celiac disease (CD).

METHODS

IgA-tTG and IgG-tTG were measured with radioligand binding assays (RBA) using human recombinant (hr) (35)S-tTG produced in lysate of rabbit reticulocytes and with guinea pig (gp) tTG ELISA in 51 CD children (median: 5.7 years) and 35 controls (median: 2.2 years). Assays were performed with and without calcium.

RESULTS

In hr-tTG RBA, IgA-tTG levels remained unchanged after calcium detecting 50/51 CD children and 1/35 controls (p<0.0001). IgG-tTG levels decreased with calcium (p<0.0001) in CD children and detected 48/51 with and 49/51 without calcium as compared to 1/35 controls (p<0.0001). In gp-tTG ELISA, levels increased with calcium (p<0.0001) making it possible to detect an additional three to a total of 50/51 with IgA-tTG and 13 to 39/51 CD children with IgG-tTG compared to 4/35 and 8/35 controls (respectively, p<0.0001). Rabbit reticulocytes displayed calcium-dependent tTG activity.

CONCLUSIONS

Calcium increased binding of IgA-tTG and IgG-tTG in the ELISA test. The reverse effect observed in RBA may be explained by competitive binding between calcium activated native rabbit reticulocyte tTG and hr (35)S-tTG. tTG autoantibody assays may need taking calcium into account for accurate diagnostic sensitivity and specificity for CD.

Immunoglobulin G (IgG) anti-tissue transglutaminase antibodies used as markers for IgA-deficient celiac disease patients

The role of immunoglobulin A (IgA) anti-tissue transglutaminase antibodies (IgA-tTG) as predictors of untreated celiac disease (CoD) is well documented, and the presence and levels of these antibodies are most accurately monitored with native or recombinant human antigens. However, IgA-deficient CoD patients are not identified by IgA serology, and conflicting results concerning the diagnostic validity of IgG antibodies against gliadin (IgG-AGA), endomysium (IgG-EmA), and tTG (IgG-tTG) have been reported. The aim of the present study was to evaluate the utility of IgG-tTG for the detection of CoD in IgA-deficient patients. Samples from 115 IgA-deficient and 200 IgA-sufficient subjects were collected and tested for the presence of IgA and IgG antibodies against tTG, EmA, and AGA. Antibodies against tTG were measured by an enzyme-linked immunosorbent assay based on recombinant human tTG, and antibodies against EmA were determined by immunofluorescence. The values for IgG-tTG showed a higher correlation (correlation coefficient [r] = 0.91) with those for IgG-EmA for the IgA-deficient subjects than for the IgA-sufficient subjects (r = 0.88). The overall concordance of the positive and negative results between IgG-tTG and IgG-EmA was 97%, and the IgG-tTG assay discriminated between IgG-EmA-positive and -negative subjects with IgA deficiency at a rate of 100%. Elevated levels of IgG-tTG and IgG-EmA were measured in 70% of the IgA-sufficient subjects. IgG-tTG detection with recombinant human tTG is a good alternative to IgG-EmA detection, and the addition of IgG-tTG assessment to present screening methods may improve the ability to identify IgA-deficient subjects with CoD.

What are the sensitivity and specificity of serologic tests for celiac disease? Do sensitivity and specificity vary in different populations?

A number of serologic tests are available commercially for identifying individuals who require an intestinal biopsy examination to diagnose celiac disease (CD). The aim of this study was to determine which test, or combination of tests, was most sensitive and specific for this purpose. We performed a literature review of studies that determined the sensitivity and specificity of serologic tests for CD. Studies that compared biopsy examination-confirmed cases of CD with controls with normal intestinal histology were selected for analysis. Sensitivities and specificities for the antigliadin tests were highly variable. Immunoglobulin (Ig)G-based antigliadin (AGA) tests generally were poor in both parameters whereas the IgA-based test was poorly sensitive but more specific. The IgA endomysium (EMA-IgA) and tissue transglutaminase (TTG-IgA) tests were both highly sensitive and specific with values for both parameters exceeding 95% in most studies. There were no identifiable differences between adults and children with respect to these tests. There was no evidence that a combination of tests was better than a single test using either the EMA IgA or TTG IgA. Either the EMA-IgA or TTG-IgA test is most useful for identifying individuals with CD. The variability and generally lower accuracy associated with the AGA tests make them unsuitable for screening purposes. There is no advantage to using a panel of tests as opposed to a single test. Because these data were obtained largely from studies conducted in a research setting, it is possible the tests will be less accurate when used in the clinical setting.

Need for quantitative assessment of transglutaminase autoantibodies for celiac disease in screening-identified children

OBJECTIVES

To assess several transglutaminase autoantibody (TGAA) assays in their ability to distinguish celiac disease (CD) in screening-identified children with abnormal intestine biopsy specimens from those with normal biopsy specimens.

STUDY DESIGN

Children at risk for CD (n = 54) composed of type 1 diabetics, first-degree relatives of type 1 diabetics or CD, and HLA-DQ2+ individuals followed from birth received intestine biopsy. Sera obtained at the time of biopsy were tested for TGAA, using the radioimmunoassay and 5 other commercially available enzyme-linked immunosorbent assays.

RESULTS

False-positive rates ranged from 28% to 80%. The positive predictive value (PPV) of the tests ranged from 63% to 84% (lower than reported for symptomatic children). Setting a higher cutoff for each assay maximized PPV.

CONCLUSIONS

There are significant quantitative differences among all TGAA assays that could affect interpretation of a positive test for CD. The overall false-positive rate for all assays was high in this population. Using the assay as a quantitative rather than qualitative tool by increasing the cutoff of positivity to indicate biopsy increases PPV. Multicenter workshops are needed to identify critical differences and to standardize TGAA assays among laboratories.

Enhanced interleukin-18 levels in the peripheral blood of children with coeliac disease

Coeliac disease (CoD) is a small intestinal disorder characterized by villous atrophy, crypt cell hyperplasia and an increased production of T helper cell type 1 (Th1) cytokines. Interleukin (IL)-18 is a pro-inflammatory cytokine that has a crucial role in maintaining the Th1 response. In this study, the serum levels of IL-18 were measured in children with CoD or other gastrointestinal diseases in order to evaluate the possibility of using IL-18 as a disease activity marker. IL-18 levels were higher in samples from CoD patients [median 443 pg/ml (148-885)] compared to healthy controls [median 205 pg/ml (11-379)], P <0.05. In contrast, the levels of IL-18 were not enhanced significantly in the serum from patients with inflammatory bowel disease (IBD) [median 324 pg/ml (207-546)] or in the disease control group [median 303 pg/ml (2-689)]. In CoD patients, after 2 weeks of gluten challenge (GC), serum IL-18 was unchanged [median 268 pg/ml (59-458)] compared to patients on a gluten-free diet [median 220 pg/ml (53-600)], while IL-18 was increased after 12 weeks of GC [median 551 pg/ml (94-952)], P <0.01. The IL-18 levels correlated with IgA anti-transglutaminase antibody levels (rs=0.59, P=0.016) in serum from untreated CoD patients, and IL-18 also followed the degree of small intestinal villous atrophy in 12 out of 19 CoD patients. Our results support the view that serum IL-18 concentrations in children with CoD follow disease activity, suggesting a role for IL-18 in the induction of an inflammatory Th1-response after gluten exposure.

Antitissue transglutaminase and antithyroid autoantibodies in children with Down syndrome and celiac disease

OBJECTIVES

We measured circulating autoantibodies and evaluated the potential of circulating antitissue transglutaminase (tTG) antibodies to determine the presence of celiac disease (CD) in children with Down syndrome.

METHODS

An ELISA based on recombinant human tTG was used to measure the levels of immunoglobulin A and immunoglobulin G antibodies in serum samples from 72 children with Down syndrome, 52 children with biopsy-verified CD, 21 disease controls with a normal small intestinal mucosa and 23 healthy controls. Of the 72 Down syndrome children, 11 under-went a small intestinal biopsy.

RESULTS

Four of 72 children with Down syndrome were diagnosed as having CD and three of them had serum levels of immunoglobulin A tTG antibodies greater than 6 U/mL (668, 147 and 7 U/mL). One Down syndrome child with biopsyproven CD had normal levels of immunoglobulin A tTG. Two Down syndrome children had increased levels of immunoglobulin A tTG (13 and 7 U/mL) but none of these children had an intestinal biopsy performed. Of the 52 CD subjects (median 664 U/mL) one was negative for immunoglobulin A tTG (5 U/mL) and all healthy controls (median 1.2 U/mL) and disease controls (median 0.9 U/mL) had immunoglobulin A tTG antibody levels less than 6 U/mL. Two of four Down syndrome children with CD and 36 of 52 celiac children had increased serum levels of immunoglobulin G tTG antibodies. There was no correlation between the serum levels of tTG and antithyroid autoantibodies.

CONCLUSIONS

Although the diagnosis of CD depends on histologic evaluation of intestinal biopsies, detection of anti-tTG antibodies provides a useful complementary diagnostic method for CD in children with Down syndrome.

Antibody levels in adult patients with coeliac disease during gluten-free diet: a rapid initial decrease of clinical importance

OBJECTIVE

Analysis of antibodies against tissue transglutaminase (tTG) has been shown valuable in the diagnosis of coeliac disease (CD) but how quickly serum titres decrease after introduction of a gluten-free diet (GFD) is not known in adults. CD is a well-recognized disorder amongst the general population and many persons try a GFD for fairly vague symptoms before they seek medical advice. Therefore, it is important to determine the time that the serologic tests remain predictive of the disease after the introduction of a GFD.

METHODS

Sera were taken from 22 consecutively biopsy-proven adult patients with CD in connection with the diagnostic biopsy. The patients were followed for 1 year and sera were taken after 1, 3, 6 and 12 months after start of a GFD. Sera were stored at -20 degrees C and analysed for IgA antibodies against gliadin, endomysium and two different commercial tTG assays based on recombinant human tTG (tTGrh) and guinea-pig liver (tTGgp).

RESULTS

Twenty patients could be followed during GFD and all antibody titres fell sharply within 1 month after introduction of a GFD and continued to decline during the survey interval. Thirty days after beginning the diet only 58, 84, 74 and 53% of all patients had positive antibody levels of tTGrh, tTGgp, EmA and AGA respectively.

CONCLUSIONS

As the antibodies used to confirm the diagnosis of CD fall rapidly and continue to decline following the introduction of a GFD, it is important that health care providers carefully inquire about the possibility of self-prescribed diets before patients sought medical attention.

Apresentação clínica de doença celíaca em crianças durante dois períodos, em serviço universitário especializado

RACIONAL: Estudos demonstram mudança na forma de apresentação clínica da doença celíaca, com aumento da ocorrência de formas atípicas tanto em crianças, como em adultos. OBJETIVO: Verificar este fato em crianças atendidas em serviço universitário especializado (Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, SP.). MÉTODOS: Foram estudados pacientes celíacos em dois períodos: de janeiro de 1978 a dezembro de 1987 (grupo 1 = G1) e janeiro de 1988 a dezembro de 1997 (grupo 2 = G2). Foram analisados: tempo de doença, idade ao diagnóstico, estado nutricional e formas clínicas. Considerou-se forma típica se o paciente tinha pelo menos dois dos seguintes sinais/sintomas: diarréia, distensão abdominal, perda de peso, associados ou não a outros. A análise estatística foi realizada pelos testes exato de Fisher e de Wilcoxon. RESULTADOS: Mediana de idade ao diagnóstico: 23 meses (G1) e 21 (G2). Intervalo entre início de sintomas e diagnóstico: 13 meses (G1) e 11 (G2). Estado nutricional (%) Gomez: G1:eutrofia = 23,8; DI = 47,61; DII = 23,8 e DIII = 4,76. G2: eutrofia = 20,68, DI = 48,27, DII = 27,58 e DIII = 3,44. Waterloo: G1: eutrofia = 23,8, emaciação = 14,28 baixa estatura = 28,57 e crônico = 33,33. G2: eutrofia = 20,68, emaciação = 13,79, baixa estatura = 34,48 e crônico = 31,03. Formas clínicas (%) - G1: típica 57,14 e atípica 42,85. G2: típica 55,18 e atípica 44,82. Nenhum dado foi estatisticamente diferente nos dois grupos. CONCLUSÕES: No estudo não se encontrou mudança nas formas de apresentação e demais características clínicas da doença celíaca. Cogita-se que essa hipótese poderia ser decorrente de características populacionais, de diferenças na abordagem nos serviços de saúde ou de diferentes períodos de observação, em comparação com os demais estudos.

Epitopes recognised by tissue transglutaminase antibodies in coeliac disease

The interaction between IgA tissue transglutaminase (tTG) antibodies (Abs) and 35S-labelled tTG produced in a transcription/translation (TnT) system with various amino acid (aa) deletions has been studied. These experiments showed that the tTG N-terminal aa 1-89 were important for tTG Ab binding in all 15 coeliac disease sera studied and the central residues (aa 401-491) were important for binding of tTG Abs in all but one sera. The contribution of C-terminal residues to tTG Ab binding varied in different coeliac sera but overall was less than the contributions of the N terminal and central regions. Mouse monoclonal antibodies (MAbs) to tTG were produced and the tTG aa sequences recognised by the MAbs determined using modified 35S-labelled tTG proteins. Analysis of the inhibiting effects of patient sera tTG Ab on binding of tTG MAbs to tTG confirmed the importance of the N-terminal and central regions of tTG in forming serum tTG Ab binding sites. Recombinant human tTG was expressed in yeast and purified to better than 95% homogeneity using MAb affinity chromatography as a final purification step. This material was highly suitable for use in an ELISA for tTGAb.

Diagnostic Accuracy of Ten Second-Generation (Human) Tissue Transglutaminase Antibody Assays in Celiac Disease

Background: Anti-tissue transglutaminase (tTG) assays that use human tTG as antigen have recently become available. We evaluated commercially available assays with human tTG antigen to estimate their diagnostic accuracies and to determine whether they agree sufficiently to be used interchangeably.

Methods: Ten commercially available second-generation anti-tTG assays were evaluated. The following populations were studied: celiac disease (CD) patients at the time of diagnosis without (n = 70) or with (n = 5) IgA deficiency; diseased controls (n = 70); and CD patients without (n = 28) or with (n = 2) IgA deficiency during follow-up. All individuals included in the study underwent intestinal biopsy. Technical performance (linearity, interference, precision, correlation, and agreement) and diagnostic accuracy (sensitivity and specificity) were compared. Anti-gliadin and anti-endomysium antibodies were also measured.

Results: IgA anti-tTG results correlated well overall, but numerical values differed. Diagnostic sensitivity ranged between 91% and 97% and specificity between 96% and 100%. These were higher than the sensitivity and specificity of the IgA endomysium assay and the IgA gliadin assay. Generally, IgG anti-tTG was less sensitive but more specific than IgG anti-gliadin for the diagnosis of CD in the small group of IgA-deficient patients.

Conclusions: Overall diagnostic performance of IgA tTG assays is acceptable and comparable among the different assays, but numerical values differ. Standardization is needed.

Anti-human versus anti-guinea pig tissue transglutaminase antibodies as the first-level serological screening test for coeliac disease in the general population

BACKGROUND

So far the reliability of the anti-guinea pig and anti-human tissue transglutaminase antibodies for the coeliac disease diagnosis has been evaluated in selected groups of patients.

AIM

To compare the diagnostic accuracy of anti-human versus anti-guinea pig tissue transglutaminase in the coeliac disease screening of the general population.

SUBJECTS

Two healthy Italian populations living in Marche region and in Western Sardinia.

METHODS

Both anti-guinea pig and anti-human tissue transglutaminase were determined using an enzyme-linked immunosorbent assay-based commercially available kit (Eu-tTG, Eurospital, Trieste, Italy).

RESULTS

During the period 1999-2001, 3541 subjects (1500 from "continental" Italy and 2041 from Sardinia) were screened for coeliac disease using both anti-guinea pig and anti-human tissue transglutaminase as first-level tests. Both these tests were negative in 3439/3541 sera, while 29 resulted positive for both of them and 73 showed discordant results. Overall, 50 intestinal biopsies were performed in 22, 21 and 7 subjects with positivity to both screening tests, to anti-guinea pig and to anti-human tissue transglutaminase alone, respectively. A coeliac disease diagnosis was made in 25 subjects giving an overall prevalence of 1:126 individuals. The anti-tissue transglutaminase specificity and sensitivity were 98 and 92% for guinea pig and 99.6 and 96% for human tissue transglutaminase, respectively.

CONCLUSIONS

The anti-human tissue transglutaminase test should definitely replace the anti-guinea pig-derived one as first-level screening tool for identifying all subjects who need the second-level investigations (small intestinal biopsy).