Endomysial antibodies in the diagnosis of celiac disease and the effect of gluten on antibody titers

Latitude and Celiac Disease Prevalence: A Meta-Analysis and Meta-Regression

BACKGROUND & AIMS

The latitudinal gradient effect is described for several autoimmune diseases including celiac disease in the United States. However, the association between latitude and global celiac disease prevalence is unknown. We aimed to explore the association between latitude and serology-based celiac disease prevalence through meta-analysis.

METHODS

We searched MEDLINE, Embase, Cochrane, and Scopus databases from their beginning through June 29, 2018, to identify screening studies that targeted a general population sample, used serology-based screening tests, and provided a clear location from which we could assign a latitude. Studies were excluded if sampling was based on symptoms, risk factors, or referral. Study selection and data extraction were performed by independent reviewers. The association measures between latitude and prevalence of serology-based celiac disease were evaluated with random-effects meta-analyses and meta-regression.

RESULTS

Of the identified 4667 unique citations, 128 studies were included, with 155 prevalence estimates representing 40 countries. Celiac disease was more prevalent at the higher latitudes of 51° to 60° (relative risk [RR], 1.62; 95% CI, 1.09-2.38) and 61° to 70° (RR, 2.30; 95% CI, 1.36-3.89) compared with the 41° to 50° reference level. No statistically significant difference was observed at lower latitudes. When latitude was treated as continuous, we found a statistically significant association between CD prevalence and latitude overall in the world (RR, 1.03, 95% CI, 1.01-1.05) and a subregional analysis of Europe (RR, 1.05; 95% CI, 1.02-1.07) and North America (RR, 1.1; 95% CI, 1.0-1.2).

CONCLUSIONS

In this comprehensive review of screening studies, we found that a higher latitude was associated with greater serology-based celiac disease prevalence.

Reproductive Characteristics and Pregnancy Outcomes in Hidden Celiac Disease Autoimmunity

INTRODUCTION

Untreated symptomatic celiac disease (CD) adversely affects female reproduction; however, the effect of hidden CD autoimmunity is uncertain.

METHODS

We identified women who were not previously diagnosed with CD and tested positive for tissue transglutaminase and endomysial antibodies between 2006 and 2011 in a community-based retrospective cohort study. We evaluated (i) the rate of adverse pregnancy outcomes and medical complications of pregnancy in successful singleton deliveries and (ii) reproductive characteristics in seropositive women without a clinical diagnosis of CD and age-matched seronegative women.

RESULTS

Among 17,888 women whose serum samples were tested for CD autoimmunity, 215 seropositive and 415 seronegative women were included. We reviewed 231 and 509 live singleton deliveries of 117 seropositive and 250 seronegative mothers, respectively. Menarche and menopausal age, gravidity, parity, and age at first child were similar in seropositive and seronegative women. CD seropositivity was not associated with an increased risk of maternal pregnancy complications. Maternal seropositivity was associated with small for gestational age in boys (OR 3.77, 95% CI: 1.47-9.71; P = 0.006), but not in girls (OR 0.57, 95% CI: 0.15-2.17; P = 0.41). CD serum positivity was not associated with prematurity, small for gestational age (birth weight <10th percentile), or 5-minute Apgar score of less than 7.

DISCUSSION

Although underpowered, the present study did not show any difference in reproductive characteristics or rates of adverse pregnancy outcomes in women with and without CD autoimmunity, except for birth weight in male offspring. Larger studies are needed to determine the effects of CD autoimmunity on female reproduction.

The industrial food additive, microbial transglutaminase, mimics tissue transglutaminase and is immunogenic in celiac disease patients

Microbial transglutaminase (mTg) is capable of cross-linking numerous molecules. It is a family member of human tissue transglutaminase (tTg), and is involved in CD. Despite declarations of the safety of mTg for industrial use, direct evidence for immunogenicity of the enzyme is lacking. The serological activity of mTg, tTg, gliadin complexed mTg (mTg neo-epitope) and gliadin complexed tTg (tTg neo-epitope) were studied in 95 pediatric celiac patients (CD), 99 normal children (NC), 79 normal adults (NA) and 45 children with nonspecific abdominal pain (AP). Sera were tested by ELISAs, detecting IgA, IgG or both IgA and IgG (check): AESKULISA® tTg (tTg), AESKULISA® tTg New Generation (tTg neo-epitope (tTg-neo)), microbial transglutaminase (mTg) and mTg neo-epitope (mTg-neo). Marsh criteria were used for the degree of intestinal injury. Parallel, mTg and tTg neo-epitopes were purified by asymmetric field flow fractionation, confirmed by multi-light-scattering and SDS-PAGE, and analyzed in adult CD and control groups by competition ELISAs. No sequence homology but active site similarity were detected on alignment of the 2 Tgs. Comparing pediatric CD patients with the 2 normal groups: mTg-neo IgA, IgG and IgA+IgG antibody activities exceed the comparable mTg ones (p<0.0001). All mTg-neo and tTg-neo levels were higher (p<0.001). tTg IgA and IgG+IgA were higher than mTg IgA and IgA+IgG (p<0.0001). The levels of tTg-neo IgA/IgG were higher than tTg IgA/IgG (p<0.0001). The sequential antibody activities best reflecting the increased intestinal damage were tTg-neo check>tTg-neo IgA≥mTg-neo IgG>tTg-neo IgG>mTg-neo check>mTg-neo IgA. Taken together, tTg-neo check, tTg-neo IgA and mTg-neo IgG correlated best with intestinal pathology (r²=0.6454, r²=0.6165, r²=0.5633; p<0.0001, p<0.0001, p<0.0001, respectively). Purified mTg-neo IgG and IgA showed an increased immunoreactivity compared to single mTg and gliadin (p<0.001) but similar immunoreactivity to the tTg-neo IgG and IgA ELISA. Using competition ELISA, the mTg neo-epitopes and tTg neo-epitopes have identical outcomes in CD sera both showing a decrease in optical density of 55±6% (p<0.0002). mTg is immunogenic in children with CD and, by complexing to gliadin, its immunogenicity is enhanced. Anti-mTg-neo-epitope IgG antibodies correlate with intestinal damage to a comparable degree as anti-tTg-neo IgA. mTg and tTg display a comparable immunopotent epitope. mTg-neo IgG is a new marker for CD. Further studies are needed to explore the pathogenic potential of anti-mTg antibodies in CD.

Screening for celiac disease in a North American population: sequential serology and gastrointestinal symptoms

OBJECTIVES

The prevalence of diagnosed celiac disease is <1 in 2,000 in the United States, but screening studies undertaken in European and other populations have revealed a much higher prevalence. The objective of this study was to determine the prevalence of celiac disease and the utility of screening in the general adult population of a geographically isolated area.

METHODS

Serum tissue transglutaminase antibodies (tTG-IgA) were measured in volunteer health-care participants aged ≥ 18 years at the annual Casper, Wyoming, Blue Envelope Health Fair blood draw. Subjects with positive tTG-IgA tests had their endomysial IgA antibodies checked. Double positives were offered endoscopy with small bowel biopsy. All subjects completed a short gastrointestinal (GI) symptom questionnaire.

RESULTS

A total of 3,850 residents of the Natrona County had serologic evaluation for celiac disease, 34 of whom tested positive for both tTG and endomysial antibody (EMA) IgA. Excluding three individuals with previous diagnosis of celiac disease, the overall prevalence of positive celiac serology in this community sample was 0.8%. All 31 subjects were offered a small bowel biopsy. Of the 18 biopsied subjects, 17 (94%) had at least partial villous atrophy. Symptoms that were reported by the fair attendees did not predict positivity.

CONCLUSIONS

Screening for celiac disease was widely accepted in this preventative health-care setting. Undiagnosed celiac disease affects 1 in 126 individuals in this Wyoming community. Most were asymptomatic or had atypical presentations. Serologic testing can readily detect this disease in a general population.

Genetics and pathogenesis of coeliac disease

Coeliac disease is a common complex disease caused by a dietary intolerance to wheat gluten. Susceptibility is determined by both environmental and genetic factors. Coeliac disease results from complex interactions between the innate immune system, an adaptive T and B cell response and the mucosal barrier where inflammation is ultimately manifested. Genetic variants within the HLA region are well established, while variants outside of the HLA region have recently been identified. These variants are beginning to enhance our understanding of the immunology of the condition. This review focuses on the immunological pathogenesis of coeliac disease with special reference to the influence of genetic susceptibility on disease development.

Coeliac disease: a diverse clinical syndrome caused by intolerance of wheat, barley and rye

Coeliac disease is a lifelong intolerance to the gluten found in wheat, barley and rye, and some patients are also sensitive to oats. The disease is genetically determined, with 10% of the first-degree relatives affected and 75% of monozygotic twins being concordant. Of the patients with coeliac disease 95% are human leucocyte antigen (HLA)-DQ2 or HLA-DQ8 positive. Characteristically, the jejunal mucosa becomes damaged by a T-cell-mediated autoimmune response that is thought to be initiated by a 33-mer peptide fragment in A2 gliadin, and patients with this disorder have raised levels of anti-endomysium and tissue transglutaminase antibodies in their blood. Coeliac disease is the major diagnosable food intolerance and, with the advent of a simple blood test for case finding, prevalence rates are thought to be approximately 1:100. Classically, the condition presented with malabsorption and failure to thrive in infancy, but this picture has now been overtaken by the much more common presentation in adults, usually with non-specific symptoms such as tiredness and anaemia, disturbance in bowel habit or following low-impact bone fractures. Small intestinal biopsy is necessary for diagnosis and shows a characteristically flat appearance with crypt hypoplasia and infiltration of the epithelium with lymphocytes. Diet is the key to management and a gluten-free diet effectively cures the condition. However, this commitment is lifelong and many aisles in the supermarket are effectively closed to individuals with coeliac disease. Compliance can be monitored by measuring antibodies in blood, which revert to negative after 6-9 months. Patients with minor symptoms, who are found incidentally to have coeliac disease, often ask whether it is necessary to adhere to the diet. Current advice is that dietary adherence is necessary to avoid the long-term complications, which are, principally, osteoporosis and small bowel lymphoma. However, risk of these complications diminishes very considerably in patients who are on a gluten-free diet.

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.

Coeliac disease

Coeliac disease is a genetically-determined chronic inflammatory intestinal disease induced by an environmental precipitant, gluten. Patients with the disease might have mainly non-gastrointestinal symptoms, and as a result patients present to various medical practitioners. Epidemiological studies have shown that coeliac disease is very common and affects about one in 250 people. The disease is associated with an increased rate of osteoporosis, infertility, autoimmune diseases, and malignant disease, especially lymphomas. The mechanism of the intestinal immune-mediated response is not completely clear, but involves an HLA-DQ2 or HLA-DQ8 restricted T-cell immune reaction in the lamina propria as well as an immune reaction in the intestinal epithelium. An important component of the disease is the intraepithelial lymphocyte that might become clonally expanded in refractory sprue and enteropathy-associated T-cell lymphoma. Study of the mechanism of the immune response in coeliac disease could provide insight into the mechanism of inflammatory and autoimmune responses and lead to innovations in treatment.

Reliability of antitransglutaminase antibodies as predictors of gluten-free diet compliance in adult celiac disease

OBJECTIVE

Strict lifelong compliance to a gluten-free diet (GFD) minimizes the long-term risk of mortality, especially from lymphoma, in adult celiac disease (CD). Although serum IgA antitransglutaminase (IgA-tTG-ab), like antiendomysium (IgA-EMA) antibodies, are sensitive and specific screening tests for untreated CD, their reliability as predictors of strict compliance to and dietary transgressions from a GFD is not precisely known. We aimed to address this question in consecutively treated adult celiacs.

METHODS

In a cross-sectional study, 95 non-IgA deficient adult (median age: 41 yr) celiacs on a GFD for at least 1 yr (median: 6 yr) were subjected to 1) a dietician-administered inquiry to pinpoint and quantify the number and levels of transgressions (classified as moderate or large, using as a cutoff value the median gluten amount ingested in the overall noncompliant patients of the series) over the previous 2 months, 2) a search for IgA-tTG-ab and -EMA, and 3) perendoscopic duodenal biopsies. The ability of both antibodies to discriminate celiacs with and without detected transgressions was described using receiver operating characteristic curves and quantified as to sensitivity and specificity, according to the level of transgressions.

RESULTS

Forty (42%) patients strictly adhered to a GFD, 55 (58%) had committed transgressions, classified as moderate (< or = 18 g of gluten/2 months; median number 6) in 27 and large (>18 g; median number 69) in 28. IgA-tTG-ab and -EMA specificity (proportion of correct recognition of strictly compliant celiacs) was 0.97 and 0.98, respectively, and sensitivity (proportion of correct recognition of overall, moderate, and large levels of transgressions) was 0.52, 0.31, and 0.77, and 0.62, 0.37, and 0.86, respectively. IgA-tTG-ab and -EMA titers were correlated (p < 0.001) to transgression levels (r = 0.560 and R = 0.631, respectively) and one to another (p < 0.001) in the whole patient population (r = 0.834, N = 84) as in the noncompliant (r = 0.915, N = 48) group. Specificity and sensitivity of IgA-tTG-ab and IgA-EMA for recognition of total villous atrophy in patients under a GFD were 0.90 and 0.91, and 0.60 and 0.73, respectively.

CONCLUSIONS

In adult CD patients on a GFD, IgA-tTG-ab are poor predictors of dietary transgressions. Their negativity is a falsely secure marker of strict diet compliance.

The use of a single serological marker underestimates the prevalence of celiac disease in Israel: a study of blood donors

OBJECTIVES

Recent studies suggest that celiac disease was previously underdiagnosed. To find out whether antiendomysial antibodies underestimate the prevalence of celiac disease, we elected to use a strategy combining multiple serological markers to explore the prevalence of celiac disease in Israel and the usefulness of the various antibodies in screening for celiac disease.

METHODS

Serum samples from 1571 healthy blood donors were tested. A small intestinal biopsy was offered to all patients who tested positive for either human tissue transglutaminase antibodies, an ELISA kit based on antiendomysium (EMA-ELISA), immunoglobulin A antigliadin verified by antiendomysial immunofluorescence antibodies, and to patients who were IgA deficient with elevated antigliadin IgG.

RESULTS

A total of 59 subjects (3.8% of study population) were offered an intestinal biopsy based on serological findings, and 30 of 59 patients agreed to undergo intestinal biopsy (1.9% of study population). Celiac disease was diagnosed in 10 patients, establishing a prevalence of at least 1:157 in the general population (0.6%, CI = 0.3-1.1%). Using any serological marker alone would have underestimated the prevalence of celiac disease, as it was diagnosed in only two patients who tested positive for endomysial immunofluorescence antibodies (prevalence of 1:786, 0.1%, CI = 0.02-0.5%), six patients positive for tissue transglutaminase (prevalence of 1:262, 0.4%, CI = 0.1-0.9%), and seven patients positive for ELISA-EMA (prevalence of 1:224, 0.45%, CI = 0.2-0.9%).

CONCLUSIONS

The prevalence of celiac disease in Israel is at least 1:157 in the general population, confirming its underdiagnosis in previous studies. The disparity between the various serological markers suggest that the use of one serological marker is insufficient for establishing the true prevalence of celiac disease.

Celiac disease-associated autoimmune endocrinopathies

Celiac disease (CD) is an autoimmune disorder induced by gluten intake in genetically susceptible individuals. It is characterized by the presence of serum antibodies to endomysium, reticulin, gliadin, and tissue transglutaminase. The incidence of CD in various autoimmune disorders is increased 10- to 30-fold in comparison to the general population, although in many cases CD is clinically asymptomatic or silent. The identification of such cases with CD is important since it may help in the control of type I diabetes or endocrine functions in general, as well as in the prevention of long-term complications of CD, such as lymphoma. It is believed that CD may predispose an individual to other autoimmune disorders such as type I diabetes, autoimmune thyroid, and other endocrine diseases and that gluten may be a possible trigger. The onset of type I diabetes at an early age in patients with CD, compared to non-CD, and the prevention or delay in onset of diabetes by gluten-free diet in genetically predisposed individuals substantiates this antigen trigger hypothesis. Early identification of CD patients in highly susceptible population may result in the treatment of subclinical CD and improved control of associated disorders.

Antiendomysium antibodies in Brazilian patients with celiac disease and their first-degree relatives

BACKGROUND

Literature data have shown high specificity of antiendomysial antibodies (EmA IgA) in celiac disease. The scarcity of Brazilian reports concerning this subject motivated the present study.

OBJECTIVES

To determine the sensitivity and specificity of antiendomysial IgA antibodies in Brazilian celiac patients at diagnosis and after treatment, to confirm patient adherence to a gluten-free diet and to screen first-degree relatives.

METHODS

An extensive clinical and serological study was performed by investigating the presence of these antibodies in 392 individuals from Southern Brazil. Indirect immunofluorescence using human umbilical cord as substrate was employed and the total levels of IgA were determined by turbidimetry in all groups. The study was conducted on 57 celiac patients (18 at diagnosis, 24 who adhered to a gluten-free diet and 15 with marked or slight transgression of the diet), 115 relatives of celiac patients (39 families), 94 patients with other gastrointestinal diseases, and 126 healthy individuals from the general population.

RESULTS

The results demonstrated 100% positivity for the recently diagnosed patients and for those consuming gluten, in contrast to the patients who complied with the diet (0%). In the control group one individual was positive, but refused to undergo a biopsy. In the group of other gastrointestinal diseases, one positive patient presented ulcerative colitis, Down's syndrome and epilepsy, and the intestinal biopsy was diagnostic for celiac disease. These data showed 99.3% specificity for the test. Eighteen relatives were positive for antiendomysial antibodies IgA (15.65%), and comparison with the healthy population revealed a significant difference. An intestinal biopsy was obtained from seven subjects (one with total villous atrophy and six without alterations in the mucosal architecture, but all with a high number of intra-epithelial lymphocytes).

CONCLUSIONS

The method revealed 100% sensitivity and 99.3% specificity. Because it is not an invasive method it can be used for the screening of atypical and latent forms of celiac disease to avoid serial biopsies and to control adherence to a gluten-free diet with implications in the prevention of malignancy in celiac disease.

Vitamin B12 deficiency in untreated celiac disease

OBJECTIVES

Iron and folate malabsorption are common in untreated celiac disease as the proximal small intestine is predominantly affected. Vitamin B12 deficiency is thought to be uncommon, as the terminal ileum is relatively spared. This study aims to investigate the prevalence of vitamin B12, deficiency in patients with untreated celiac disease.

METHODS

Prospective study of 39 consecutive biopsy-proven celiac disease patients (32 women, seven men; median age 48 yr, range 22-77 yr) between September 1997 and February 1999. The full blood count, serum vitamin B12, red blood cell folate, and celiac autoantibodies (IgA antigliadin and IgA antiendomysium antibodies) were measured before and after a median of 4 months (range 2-13 months) of treatment with a gluten-free diet. In vitamin B12-deficient patients, intrinsic factor antibodies and a Schilling test, part 1, were performed.

RESULTS

A total of 16 (41%) patients were vitamin B12 deficient (<220 ng/L) and 16 (41%) patients (11 women and live men) were anemic. Concomitant folate deficiency was present in only 5/16 (31%) of the vitamin B12 patients. The Schilling test, performed in 10 of the vitamin B12-deficient patients, showed five low and five normal results. Although only five patients received parenteral vitamin B12, at follow-up the vitamin B12 results had normalized in all patients. Acral paraesthesia at presentation in three vitamin B12-deficient patients resolved after vitamin B12 replacement.

CONCLUSIONS

Vitamin B12 deficiency is common in untreated celiac disease, and concentrations should be measured routinely before hematinic replacement. Vitamin B12 concentrations normalize on a gluten-free diet alone, but symptomatic patients may require supplementation.

Prevalence of IgA-antiendomysial antibody in asymptomatic low bone mineral density

OBJECTIVE

Celiac disease (CD) is a relatively common gastrointestinal disorder that can be asymptomatic. However, even among asymptomatic patients a long-term reduction in bone mineral density (BMD) is found. Excellent noninvasive screening tests for CD are now available. Studies using older screening techniques have suggested a 10-fold increased prevalence of CD among patients with low BMD, but this has not been confirmed with current testing methodology. We set out to confirm these prevalence estimates using antiendomysial antibody testing.

METHODS

A total of 100 consecutive patients referred to our outpatient endocrinology clinic for evaluation of idiopathic low BMD were studied. In addition to the routine evaluation, patients completed a symptom questionnaire and underwent serological testing for the presence of the IgA antiendomysial antibody (EMA). All patients with a positive EMA underwent small bowel biopsy and permeability studies.

RESULTS

EMA results were available on 96 patients; 78/96 patients were female and the mean age was 57 yr (range 18-86 yr). Seven of 96 (7.3% [95% CI 2.1-12.5%]) were EMA-positive, but all tests were low titer (< or = 1:20). However, none of the biopsies showed any histopathological features of CD, nor did EMA status correlate with any of the clinical or laboratory features assessed.

CONCLUSIONS

Despite a high rate of weakly positive antibody tests, our data do not support an increased prevalence of CD among asymptomatic patients referred for evaluation of low BMD. Without an increase over the background prevalence, the high cost of EMA testing argues against routine use of this test for screening of this population.

Celiac disease diagnosis in misdiagnosed children

Antiendomysial antibodies (EMA) are today considered the most sensitive and specific serological marker of celiac disease (CD). The aim of the present study was to assess the occurrence of EMA of IgG isotype in EMA IgA negative children with clinical suspicion of malabsorption and their relationship with CD. Serum EMA IgG1 determination was performed on 30 EMA IgA negative children with clinical suspicion of CD. Total serum IgA levels were further investigated. Sixty children with gastroenterological diseases other than CD were used as control disease patients and 63 healthy children were evaluated as the control group. Eighteen out of 30 children in the study showed EMA IgG1 positivity in sera and a villous height/crypt depth ratio <3:1 as index of intestinal atrophy. It is noticeable that a selective IgA deficiency was present in only 9 of 18 EMA IgG1 positive children. In addition, clinical symptoms, EMA IgG1, and mucosal atrophy disappeared after 8-10 mo on a gluten-free diet. Neither EMA IgA nor EMA IgG1 were detected in the children in the control groups. The other 12 children in study group showed no histologic abnormalities and were EMA IgG1 negative. In this study, we reveal a group of EMA IgG1 CD children without IgA deficiency. The diagnosis was based on the presence of gluten-dependent typical serological and histologic features of CD. Our data suggest that EMA IgG1 determination could be a new tool in the diagnostic workup of CD, useful in avoiding possible misdiagnosis.

Endomysial antibody in the diagnosis and management of coeliac disease

This review determines the significance, usefulness, and application of the endomysial antibody test for coeliac disease in clinical practice.

Anti-transglutaminase antibodies and coeliac disease

BACKGROUND

Anti-endomysial antibodies have high specificity for coeliac disease but measurements are limited by the requirement for monkey oesophagus, a substrate that is expensive, and of limited availability and ethical acceptance. Tissue transglutaminase has recently been identified as the endomysial autoantigen in coeliac disease.

AIMS

To examine the validity of serum tissue transglutaminase antibody levels in patients with coeliac disease and to assess their sensitivity and specificity against standard serological tests.

METHODS

Serum IgA anti-tissue transglutaminase antibody titres (measured by ELISA), IgA anti-gliadin antibody titres (measured by a commercial ELISA) and anti-endomysial antibody titres (measured by indirect immunofluorescence) were determined in 46 untreated and 14 treated patients biopsy-proven coeliac disease and 145 disease and healthy controls.

RESULTS

All patients with untreated coeliac disease were positive for anti-endomysial and anti-tissue transglutaminase antibodies (sensitivity 100%). Seventy-one per cent of treated coeliac patients were anti-tissue transglutaminase antibody negative. Five of 145 disease and healthy controls had low titres of anti-tissue transglutaminase antibody (specificity 97%); no controls were anti-endomysial antibody positive.

CONCLUSIONS

Our results demonstrated the sensitivity and specificity of IgA anti-tissue transglutaminase antibodies to correlate highly with anti-endomysial antibodies in the diagnosis of coeliac disease. The ELISA for IgA anti-tissue transglutaminase antibodies is quantitative and easy to perform and is a valid alternative to indirect immunofluorescence for anti-endomysial antibodies in screening for suspected coeliac disease.

Improved method for serological testing in celiac disease--IgA anti-endomysium antibody test: a comparison between monkey oesophagus and human umbilical cord as substrate in indirect immunofluorescence test

The IgA anti-endomysium antibody (IgA-EmA) test has been studied using the indirect immunofluorescence (IF) method with human umbilical cord (HUC) as substrate; 247 sera from patients investigated for celiac disease were tested. The results were in accordance with those obtained using monkey oesophagus (MOE) as substrate. IgA-EmA testing using HUC is shown to have similar reproducibility, sensitivity and specificity as MOE. By avoiding both fixation in chloroform and the blocking step, the processing time for this improved method is decreased by almost 1 h, and the results are stable for reading by fluorescence microscopy for at least 24 h. The indirect IF method using HUC as substrate is easy, reliable and inexpensive. We conclude that the IgA-EmA test using HUC as a substrate can be routinely used for celiac disease screening and follow up.

Further studies of anti-endomysium and anti-gliadin antibodies in patients with suspected celiac disease

BACKGROUND

The finding of characteristic small intestinal mucosal abnormalities on histologic examination of a biopsy specimen remains the first requirement for the diagnosis of celiac disease. A reliable and noninvasive test would be ideal for the patient's convenience and for reducing health-care costs. The sensitivity and specificity of anti-gliadin antibodies (AGA-immunoglobulin [Ig] G, AGA-IgA) have been variable; anti-endomysium IgA (EmA-IgA) is more helpful. In an earlier study conducted at the authors' institution, celiac disease was present in 19 patients examined from 1992 to 1995. Anti-endomysium titers were higher than normal in all 19 patients (100%). Total villous atrophy was seen in 14 of 17 biopsy specimens (82%) and subtotal atrophy in 3 (18%). The purpose of the current study was to evaluate further the accuracy of EmA-IgA in diagnosing celiac disease.

METHODS

One hundred seven patients were screened for celiac disease between March 1996 and July 1997. The level of EmA-IgA was measured in all patients, and AGA-IgG and AGA-IgA were measured in 104 patients. Forty-six patients underwent endoscopic biopsy of the small bowel, with measurement of disaccharidase enzymes in 45 patients.

RESULTS

Five of 46 patients had celiac disease (three boys and two girls; mean age, 5.3 years; 2-9.5 years); one also had cystic fibrosis and another had insulin-dependent diabetes mellitus. All five had marked to complete villous atrophy with crypt hyperplasia and increased serum EmA-IgA (100% sensitivity). None of the remaining patients had increased EmA-IgA (100% specificity). Serum levels of AGA-IgG and AGA-IgA were increased in all four celiac disease patients (100% sensitivity), but they were also high in patients without celiac disease (38% and 92% specificity, respectively), which compromises their diagnostic value. None of the patients confirmed to have celiac disease had IgA deficiency. Abnormal disaccharidase enzyme activities were documented in all five celiac disease patients: severe generalized deficiency (n = 2), moderately severe generalized deficiency (n = 2), and alactasia with moderate deficiency of the alpha-glucosidases (n = 1).

CONCLUSIONS

This study confirmed the reliability and accuracy of EmA-IgA in the diagnosis of celiac disease. Small bowel biopsy may be unnecessary in EmA-positive patients in whom celiac disease is suspected.

Biochemical tests in diseases of the intestinal tract: their contributions to diagnosis, management, and understanding the pathophysiology of specific disease states

Biochemical testing plays a major role in the complete evaluation of patients with suspected or established intestinal disease. We have classified these tests according to the medium in which they are performed: breath tests, including isotopic and nonisotopic tests, fecal tests, urine tests, serum tests, tissue tests, and other tests. The principles of various tests are outlined, and the role of each test in the evaluation of particular gastrointestinal disorders is discussed.

Antiendomysium antibodies and coeliac disease: solved and unsolved questions. An Italian multicentre study

A total of 3783 subjects were enrolled to compare IgA and IgG gliadin antibodies (AGA) with IgA endomysium antibodies (EMA) in coeliac disease (CD). Among 688 children with untreated CD EMA were positive in 93.8%, IgA AGA in 84.9% and IgG AGA in 90.2%. AGA, but not EMA, sensitivity decreased with age. EMA were present in 3.8% of control subjects, IgA AGA in 14.9% and IgG AGA in 34.3%. Follow-up of 5 of 39 EMA-positive controls showed flat mucosa. Combined determination of EMA and AGA showed an increased predictive value: if EMA and AGA were both positive, the mucosa was flat in 99.1%, if both were negative, the mucosa was normal in 99.1%. After a gluten-free diet (GFD), IgA-AGA disappeared first. Among 21 patients not on a strict GFD and in 194 coeliac patients after challenge, EMA, but not AGA, were always positive. Among 67 first-degree relatives of coeliacs, the positive predictive value of EMA was 90.6%, IgA AGA 74.3% and IgG AGA 44.6%. In conclusion, EMA screening is an excellent test for the diagnosis and follow-up of CD, and for identification of its silent and latent forms.

T cell receptor repertoire in the peripheral blood and intestinal mucosa of coeliac patients

The alpha beta and gamma delta T cell receptor (TCR) repertoire in the peripheral blood and intestinal mucosa of six coeliac and six age-matched controls was analysed by reverse transcription and polymerase chain reaction (PCR). No TCR alpha and gamma delta restriction was observed in coeliacs and controls. However, V gamma 3 was expressed only in coeliac peripheral and intestinal T cells. V delta 2 was strongly expressed in coeliacs and scarcely transcribed in control cells. The unique expression of these gamma delta TCR in coeliac patients suggests that V gamma 3 and perhaps V delta 2 TCR-bearing lymphocytes may play a role in the pathogenesis of coeliac disease.

Anti-endomysium and anti-gliadin antibodies as serological markers for coeliac disease in childhood: a clinical study to develop a practical routine

Anti-gliadin and anti-endomysium antibodies were analyzed in 174 children with suspected or verified coeliac disease with the aim of developing a practical routine. The biopsy was performed without knowledge of the antibody levels. To screen for coeliac disease is children younger than 2 years, we suggest the use of IgA anti-gliadin antibodies, giving a sensitivity of 100% and a specificity of 86%. In older children both tests should be used in parallel, i.e. a biopsy should be performed if at least one of the tests is positive, giving a sensitivity of 98% and a specificity of 81%. To avoid unnecessary biopsy before mucosal relapse can be demonstrated during gluten challenge in a child without clinical symptoms, we suggest that the tests are used as serial testing, i.e. a biopsy should be performed if both tests are positive.

Celiac disease and epilepsy in pediatric patients

Among 783 patients referred to our institute with different types of seizures as presenting symptom, systematic evaluation of antigliadin and antiendomysial antibodies in the serum has identified nine in whom jejunal biopsy has subsequently confirmed the diagnosis of celiac disease (CD). In three of them brain imaging showed the presence of calcified areas in the occipital region. They had complex partial seizures (CPS), associated in two with transient episodes of blindness. In another patient with CPS and generalized tonic-clonic seizures (GTCS) progressive multifocal cerebral calcifications were noted. In the other six patients with CPS and/or GTCS cerebral calcifications were absent. Symptoms of CD in all these cases were either not previously taken into account, or they were very mild or completely absent. In a group of 36 patients with clinically manifest CD, regular follow-up, and good compliance with the dietary regimen, no clinical seizures were reported. The pathogenetic mechanism and the relationship between epilepsy and an early diagnosis and treatment of celiac disease are discussed.

Celiac disease: clinical features and pathogenesis

Celiac disease is a fascinating illness, from both a clinical and research perspective. Most clinicians consider a diagnosis of celiac disease when a young patient has classic signs and symptoms of steatorrhea and severe malabsorption. However, the typical gastrointestinal symptoms often are absent. The patient may only have subtle signs of chronic malnutrition or nonspecific gastrointestinal complaints. Celiac disease is not diagnosed commonly in the United States, at least in part because of a low clinical index of suspicion. A diagnosis of celiac disease is confirmed by a small bowel mucosa biopsy. A dramatic clinical response to a gluten-free diet verifies the diagnosis, and provides a cost-effective treatment free of significant side effects. Strict adherence to the prescribed diet usually results in a complete resolution of the symptoms and mucosal histopathologic changes. The serious, long-term complication of intestinal lymphoma also may be prevented. To the clinical investigator, celiac disease is an important model of the HLA-associated immune-mediated illnesses. A specific HLA-DQ heterodimer is found in 95% of patients, representing perhaps the strongest association of any illness with a specific class II HLA molecule. In addition, an important environmental trigger (gluten) has been identified, providing a unique opportunity to study the interaction of gene products and environmental factors in the pathogenesis of an immune-mediated disease.

Immunological diagnosis of childhood coeliac disease: comparison between antigliadin, antireticulin and antiendomysial antibodies

The immunological markers proposed to supplement intestinal biopsy for the diagnosis of coeliac disease are antigliadin, antireticulin and antiendomysial antibodies. These antibodies have been studied separately or compared as pairs, but no prospective comparison of all three antibodies in childhood coeliac disease exists. Thirty-four confirmed coeliacs were compared with nine non-coeliacs with pathological small intestines, and 32 children with a normal intestinal histology. Sera were examined for IgG- and IgA-antigliadin antibodies (AGA) by ELISA, and for IgA-antireticulin antibodies (ARA) and IgA endomysial antibodies (EMA) by indirect immunofluorescence. In active coeliac disease, IgA-EMA was the most sensitive (97%), while IgA-AGA the least sensitive antibody (52%). The specificity of IgA-AGA, IgG-AGA, IgA-ARA, IgA-EMA was 95%, 92%, 100% and 98%, respectively. Positive predicted values of ARA and EMA were comparable (97-100%), while EMA had the highest negative predicted value (98%). Compared with IgG-AGA, IgA-EMA titres better reflected variations in dietary gluten, and correlated best with intestinal pathology. Compared with AGA and ARA sensitivity, specificity and predictive values, EMA is the most reliable serological marker for the diagnosis of coeliac disease. It reflects dietary changes in gluten and correlates best with intestinal histopathology. Therefore, it should be considered the best of the three serological tests available for childhood coeliac disease.

Immunologic and absorptive tests in celiac disease: can they replace intestinal biopsies?

The sensitivity and specificity of several immunologic and absorption tests were determined in infants with celiac disease (31 male, 39 female; median age, 2.6 years) in different phases of the disease and in a group of control subjects with chronic diarrhea of different etiologies (32 male, 28 female; median age, 1.2 years). Intestinal biopsy was performed both in the patients and in the controls as a 'gold standard' for the diagnosis. The anti-gliadin antibody (AGA) IgG values showed a sensitivity of 89% and a specificity of 47%; AGA IgA were 69% sensitive and 92% specific; anti-endomysial antibodies (EmA) were 100% sensitive and 97% specific; the xylose test was 71% sensitive and 53% specific; and the steatocrit test after a standard fatty meal was 73% sensitive and 42% specific. The authors conclude that the absorption tests cannot be used successfully in screening for celiac disease, owing to their low specificity. In contrast, EmA behavior was always in accordance with histologic findings in the various phases of celiac disease, and we would advise their use combined with AGA to obtain a sensitivity and specificity of 100%.

Food allergies in children

Ingested food represents the greatest foreign antigenic load that confronts the human immune system. In most individuals tolerance develops to food antigens that are continually gaining access to the body. When tolerance fails to develop, the immune system may react with a hypersensitivity reaction. Allergies to food affect up to 8% of children less than 3 years of age and 1% to 2% of the general population. Symptoms include the gastrointestinal, cutaneous, and respiratory symptoms, as well as systemic anaphylaxis with shock. Clinical investigations in the past have characterized the food hypersensitivity disorders, but our understanding of the basic immunopathologic mechanism remains incomplete. Current progress in allergen characterization and the rigorous scientific methods now being applied to this field by many investigators provide hope that new information regarding the pathogenesis of these disorders and new forms of therapy will soon become available. For now, practicing physicians must carefully diagnose specific food sensitivities and educate patients and their families in the elimination of the responsible food allergen.

Endomysial antibody: is it the best screening test for coeliac disease?

The sensitivities and specificities of the IgA and IgG antigliadin antibody and the IgA antireticulin antibody have been compared with the recently described endomysial antibody directed against the basement membrane of smooth muscle in monkey oesophagus. One hundred and seventeen patients with adult coeliac disease (21 untreated), 84 patients with inflammatory bowel disease, systemic lupus erythematosus and rheumatoid arthritis (comprising the disease control group), 47 normal controls and a miscellaneous group of 29 patients, who were selected because of a positive reticulin staining pattern, were investigated. These results were correlated with the degree of abnormality of the intestinal mucosa in patients with adult coeliac disease. Endomysial antibodies were found in all patients with untreated coeliac disease and subtotal villous atrophy and in 47% of patients on a non-strict gluten free diet. One patient on a strict gluten free diet was positive and had partial villous atrophy while all patients in disease control groups were negative. Results were variable with the antireticulin and antigliadin antibodies. Sensitivity and correlation with subtotal villous atrophy in the untreated patients was 100%. It is concluded that the endomysial antibody is superior to other current antibody tests and should be used in preference for the diagnosis of coeliac disease.

Predictive value for coeliac disease of antibodies to gliadin, endomysium, and jejunum in patients attending for jejunal biopsy

OBJECTIVE

To investigate the extent to which the detection of antibodies to gliadin, endomysium, and jejunum predicts the eventual diagnosis of coeliac disease according to the revised ESPGAN diagnostic criteria in a group of patients in whom there is a high suspicion of coeliac disease.

DESIGN

Clinical assessment and laboratory analysis of patients with suspected coeliac disease.

SETTING

Gastroenterology department of teaching hospital.

PATIENTS

96 adults with suspected coeliac disease attending for jejunal biopsy.

MAIN OUTCOME MEASURES

Diagnosis of coeliac disease with the revised criteria of the European Society of Paediatric Gastroenterology and Nutrition in patients with and without antibodies associated with coeliac disease.

RESULTS

28 patients had a clinical diagnosis of coeliac disease, seven of other gastrointestinal diseases, and 12 of miscellaneous diseases; 49 had no diagnosis. Gliadin IgA detected by ELISA was found in all patients with coeliac disease and none of those without, giving a sensitivity, specificity, positive and negative predictive values, and predictive efficiency of 100% for diagnosing coeliac disease within the group. Endomysial IgA was found in 25 (89%) patients with coeliac disease and jejunal IgA in 21 (75%); neither IgA was found in patients without coeliac disease.

CONCLUSION

Detection of gliadin IgA by ELISA and to a lesser extent the endomysial IgA should allow better selection of patients for jejunal biopsy and thus make diagnosing coeliac disease simpler and more efficient.

Binding to human jejunum of serum IgA antibody from children with coeliac disease

Jejunal histology and the presence of serum IgA antibodies (JAB) binding to human jejunum in vitro were studied in 139 children with severe malabsorptive symptoms. Among 33 children with confirmed coeliac disease (ESPGAN criteria), 13 (93%) of 14 sampled before starting on a gluten-free diet had JAB, none of 21 sampled had JAB while on a gluten-free diet of long duration, and 90% of 30 sampled during gluten challenge had JAB. 53 children had severe jejunal villous atrophy (probable coeliac disease): 71% of those younger than 2 years and 94% of those aged 2-18 years had JAB during gluten intake. JAB could not be detected in 53 disease control patients (normal jejunal histology) and in 3 coeliac disease patients with selective IgA deficiency. Simultaneous determination of antigliadin (AGA) and antiendomysium (EMA) levels, and gliadin and tissue absorption studies, showed that JAB and AGA are different, whereas JAB and EMA are probably identical. IgA JAB could be the target-organ-related autoantibodies in coeliac disease.