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The Turkish Journal of Gastroenterology
Turk J Gastroenterol 2012; 23 (5): 485-489
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Isolated positive anti-gliadin immunoglobin-A antibody in children with gastrointestinal symptoms
Wikrom KARNSAKUL1, 2, Kathryn SKITARELIC2, Stacey GILLESPIE2, Thaschawee ARKACHAISRI3
Department of 1Pediatrics, Johns Hopkins University School of Medicine, Baltimore, USA
Department of 2Pediatrics, West Virginia University School of Medicine, Morgantown, USA
Department of 3Pediatrics, KK Women\'s and Children\'s Hospital, Singapore, Singapore
Keywords: Isolated positive anti-gliadin immunoglobin A antibody, negative tissue transglutaminase and endomysial antibodies, celiac disease, Marsh classification, gastrointestinal symptoms, gluten hypersensitivity.
Summary
Background/aims: The use of immunoglobulin G and A anti-gliadin antibodies for celiac disease screening has decreased due to higher specificity and sensitivity of tissue transglutaminase and endomysial antibodies. Greater values of immunoglobulin-A anti-gliadin antibody have been associated with more severe mucosal damage in proven and probable celiac disease patients. The aim of this study was to determine whether anti-gliadin antibody immunoglobulin A has any clinical importance in diagnosing celiac disease in children. Children with a chronic history of vomiting, abdominal pain, diarrhea, or constipation in the outpatient clinic were evaluated for celiac disease. Materials and Methods: Tissue transglutaminase and anti-gliadin antibody immunoglobulin A in serum were determined by ELISA test and endomysial antibodies immunoglobulin A by indirect immunofluorescence. Most of these children with isolated positive anti-gliadin antibody immunoglobulin A were further evaluated by performing proximal gastrointestinal biopsies. Results: Sixteen children had isolated positive anti-gliadin antibody immunoglobulin A (negative tissue transglutaminase and endomysial antibodies immunoglobulin A). Eight were male (mean age: 9.7 years). None had immunoglobulin A deficiency. Thirteen underwent an upper endoscopy with multiple small bowel biopsies. Two patients had villous atrophy and slightly increased intraepithelial lymphocytes (Marsh 3a), which could make the diagnosis of celiac disease likely. These two patients had high titers of anti-gliadin antibody immunoglobulin A above 70 Units. Conclusions: An isolated positive antigliadin antibody immunoglobulin A result in the absence of positive tissue transglutaminase and endomysial antibodies immunoglobulin A should raise the suspicion of the diagnosis of celiac disease. This could be a non-specific phenomenon that could be found in other gastrointestinal conditions, latent celiac disease, or gluten hypersensitivity. A longitudinal clinical follow-up is recommended in these children to confirm the diagnosis.
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  • Introduction
    Celiac disease (CD) may present with both gastrointestinal and non-gastrointestinal manifestations, including symptoms such as chronic abdominal pain, constipation, vomiting, short stature, or unexplained anemia (1). The diagnosis of CD requires evaluation of clinical symptoms, serologic studies, and intestinal biopsies (1). One of the challenges in the diagnosis of CD is utilizing the serologic studies available as a noninvasive screening method to determine which patients require confirmatory testing with small bowel biopsy as a gold standard investigation. The use of anti-gliadin antibodies immunoglobulin G and A (AGA IgG and IgA) for CD screening has decreased due to the higher specificity and sensitivity of tissue transglutaminase and endomysial antibodies (TTG and EMA IgA) (1). Our aim was to determine if AGA IgA has any clinical importance in diagnosing CD in children who have chronic gastrointestinal symptoms.
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  • Materials And Methods
    Children with a chronic history of vomiting, diarrhea, abdominal pain, and other gastrointestinal symptoms were evaluated for CD in the outpatient clinic of West Virginia University Hospitals. TTG IgA and AGA IgG and IgA in serum were determined by ELISA test, and EMA IgA was determined by indirect immunofluorescence. Some children with isolated positive AGA IgA were further evaluated by proximal gastrointestinal biopsies. The number of small bowel biopsies was a minimum of four specimens from both the proximal and distal duodenum and/or jejunum. The classic pathology changes of CD in the small bowel are categorized by the Marsh classification (1) as Marsh type 0, or preinfiltrative stage with normal mucosa; type 1, or increased number of intraepithelial lymphocytes, usually exceeding 20 per 100 enterocytes; type 2, or proliferation of the crypts of Lieberkühn; type 3, or partial (3a), subtotal (3b), or complete/total villous atrophy (3c); and type 4, or hypoplasia of the small bowel architecture (total villous atrophy with crypt hyperplasia). Although HLA DQ 2 and 8 testing is not a routine test, it is performed to evaluate a tendency harboring CD in suspected CD cases (1).

    Outpatient records of these children with a chronic history of gastrointestinal symptoms were reviewed after internal review boards at West Virginia University School of Medicine approved the study.
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  • Results
    Sixteen children (8 males, 8 females; mean age: 9.7 years) had positive AGA IgA but negative TTG and EMA IgA antibodies. Vomiting, chronic intermittent diarrhea, recurrent abdominal pain, and chronic constipation were presenting symptoms in 6, 8, 13, and 4 of our patients, respectively. None had a history of steatorrhea or fat malabsorption. None had IgA deficiency. Only Patient 5 had a family history of CD. Thirteen underwent an upper endoscopy with multiple small bowel biopsies. Two patients had villous atrophy (Marsh 3a) consistent with a diagnosis of CD. Serum AGA IgA titers were significantly higher in patients who had Marsh histologic type 3a (Patients 1 and 2) as compared to those with type 0 (Patients 3-16) with the cut-off above 70 Units. Mean AGA IgA titers in type 3a vs. type 0 were 94.5 Units (70.0–119.0) vs. 31.5 Units (22.0–60.0) (Mann-Whitney test = 0.00, p=0.017). HLA DQ 2 and 8 testing was performed in only 6 patients due to insurance limitation, and 3 were positive (Table 1).

    Clinical data in all patients are summarized in Table 2. The relationship between AGA IgG, IgA antibodies and Marsh classification of intestinal biopsies are depicted in Figures 1 and 2. Patient 1 had Down syndrome and a history of duodenal atresia repair, bacterial overgrowth, and osteoporosis. Although the patient had a clinical history of CD, his HLA DQ 2 and 8 testing was negative. The parents decided not to place him on a gluten-free diet since he responded well to antibiotic therapy. All gastrointestinal symptoms of Patient 2 resolved and he was able to tolerate lactose after a gluten-free diet. The parents decided not to have a repeat endoscopy to confirm normal small intestinal pathology.
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  • Discussion
    Awareness of the CD diagnosis has increased along with the incidence of the disease since the development of CD serology. The accuracy of the serologic testing improves the screening and management outcome. Currently, most of the guidelines for the diagnosis of CD, including recommendations of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition, advise primary care physicians and gastroenterologists to start the screening with TTG IgA ELISA kits and to a lesser extent EMA IgA antibody (1). Even with newer TTG ELISA assays, the sensitivity and specificity are the low to mid 90% range.

    Negative TTG and EMA IgA results have been reported in young celiac patients (unpublished data from Tonutti et al. presented at the 5th International Congress on Autoimmunity-Sorrento, 2006). Serum AGA IgA titers were significantly higher in our patients who had Marsh histologic type 3a (Patients 1 and 2) as compared to those with type 0 (Patients 3-16). Although these two patients could have CD, the confidence level for the diagnosis was not high since EMA IgA is expected to be positive given their intestinal histology (Marsh 3a). The lack of a positive HLA DQ 2 and 8 result in Patient 1 makes the likelihood of a CD diagnosis extremely low; small bowel bacterial overgrowth could have caused the villous atrophy, increased intraepithelial lymphocytes, and mucosal inflammation in the small intestine (1). Serum AGA IgG titers were significant in both groups with Marsh histologic type 0 and 3a. This phenomenon has been reported in the era prior to the use of the more specific and sensitive antibody testing (EMA and TTG IgA), but the statistical power is still very low in this study (2). Juto et al. (2) reported that elevated serum level of AGA IgA was strongly correlated with villous atrophy and was seen in infants younger than 3 years of age. The sole appearance of conventional AGA IgA in most children with gastrointestinal symptoms may be interpreted as a non-specific immunomodulation phenomenon (3).

    Despite the higher sensitivity and specificity of TTG and EMA IgA and the NASPGHAN recommendation to use TTG IgA as the sole CD screening test, AGA IgA testing has been included in a part of CD serology as a screening panel by primary pediatricians and gastroenterologists (1). The anti-gliadin IgA and IgG tests are based on a sandwich enzyme immunoassay (ELISA) utilizing a horseradish peroxidase conjugated detection antibody. The sensitivity and specificity of anti-gliadin immunoglobulin testing has been shown to be inferior to that of TTG and EMA testing except for being slightly higher when using in treated celiac patients (1). Higher titers of AGA IgA may have more clinical significance in children with high index of suspicion for CD (4). In a study by Bonamico et al. (5), it was suggested that even low titers of AGA IgA in non-celiac patients may be an indication of increased intestinal permeability to macromolecules. In those patients with probable or proven CD, higher levels of AGA IgA of more than 70 Units/ml exhibit more severe mucosal damage in the small intestine (3). AGA IgA appeared to be a good indicator of the immune reaction in the small intestine triggered by gluten (2,6,7). The extent of elevated AGA IgA in combination with a clinical history may be valuable in discerning which patients should undergo upper endoscopy for biopsies. Therefore, it is reasonable to infer that its levels correlate to some extent with mucosal injury. In this study, we cannot conclude that having positive and/or high titers of AGA IgA is sufficient for the diagnosis of CD.

    Recently, the identification of specific B-cell epitopes on the gliadin molecule and the use of specific, synthetic, and conformationally intact B cells epitopes increasingly improved the development of the new test, Deamidated Gliadin Peptide (DGP) (8). The selective deamidation of gliadin peptide is a process in which amino acid glutamine is converted to glutamic acid in the small intestine after gluten ingestion by the enzyme TTG (8), and it immensely increases the gliadin peptide antigenicity and the sensitivity of DGP antibody assays or DPAGA IgA and IgG (9). Kaukinen (4) found that all antibody levels declined in line with mucosal recovery with a gluten-free diet. The DP-AGA antibody test interestingly was positive in six of the nine cases with small bowel mucosal damage persisting on a gluten-free diet, whereas positive TTG IgA was detected in only two cases and positive EMA IgA in none. The sensitivity and specificity are 91% and 98%, respectively (4). Unfortunately, none of our patients had residual serum stored in the laboratory to confirm the diagnosis with this test, but the patients were informed to follow up with their primary physicians for further evaluation if clinical symptoms of CD manifested later, including repeating all CD serology tests and upper endoscopy with small bowel biopsies.

    In conclusion, higher levels of AGA IgA may have more clinical significance in children with a high index of suspicion for CD. The authors believe that some of these patients who have gastrointestinal symptoms with isolated AGA IgA should be followed, since the negative results of more specific antibodies like TTG IgA or EMA IgA could be falsely negative. Further immunopathogenic study from the small bowel biopsy to detect an early phase of CD might elucidate this phenomenon in this group of patients. The use of DP-AGA IgA in conjunction with TTG and EMA IgA could provide a more sensitive screening test for further evaluation for the diagnosis of CD.
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  • Summary
  • Introduction
  • Materials And Methods
  • Results
  • Discussion
  • References
  • References
    1. Hill ID, Dirks MH, Liptak GS, et al. North American Society for Pediatric Gastroenterology, Hepatology and Nutrition. Guideline for the Diagnosis and Treatment of Celiac Disease in Children: Recommendations of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition. J Pediatr Gastroenterol Nutr 2005; 40: 1-19.

    2. Juto P, Fredrikzon B, Hernell O. Gliadin-specific serum immunoglobulins A, E, G, and M in childhood: relation to small intestine mucosal morphology. J Pediatr Gastroenterol Nutr 1985; 4: 723-9.

    3. Dinari G, Rosenbach Y, Marcus H, et al. IgA antigliadin antibodies in childhood celiac disease. Isr J Med Sci 1988; 24: 286-90.

    4. Kaukinen K, Collin P, Laurila K, et al. Resurrection of gliadin antibodies in coeliac disease. Deamidated gliadin peptide antibody test provides additional diagnostic benefit. Scand J Gastroenterol 2007; 42: 1428-33.

    5. Bonamico M, Ballati G, Mariani P, et al. Screening for coeliac disease: the meaning of low titers of anti-gliadin antibodies (AGA) in non-coeliac children. Eur J Epidemiol 1997; 13: 55-9.

    6. Savilahti E, Viander M, Perkkiö M, et al. IgA antigliadin antibodies: a marker of mucosal damage in childhood coeliac disease. Lancet 1983; 1: 320-2.

    7. Lindberg T, Nilsson LA, Borulf S, et al. Serum IgA and IgG gliadin antibodies and small intestinal mucosal damage in children. J Pediatr Gastroenterol Nutr 1985; 4: 917-22.

    8. Schwertz E, Kahlenberg F, Sack U, et al. Serologic assay based on gliadin-related nonapeptides as a highly sensitive and specific diagnostic aid in celiac disease. Clin Chem 2004; 50: 2370-5.

    9. Aleanzi M, Demonte AM, Esper C, et al. Celiac disease: antibody recognition against native and selectively deamidated gliadin peptides. Clin Chem 2001; 47: 2023-8.
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  • Summary
  • Introduction
  • Materials And Methods
  • Results
  • Discussion
  • References
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