Clinical Utility of Anti-Tissue Transglutaminase Antibodies for Diagnosis and Monitoring of Coeliac Disease in Children and Adolescents

Abstract

Identification of tissue transglutaminase (tTG) as a major target antigen of IgA anti-endomysial antibodies and detection of auto-antibodies against tTG in the serum pointed out a new direction in the serologic diagnosis of coeliac disease. Clinical utility of determination of anti-tTGIgA antibodies, with recombinant human tTG used as antigen, was evaluated for the diagnosis of coeliac disease and monitoring the adherence to the diet in children and adolescents.

Patients: The study was performed in 169 patients aged 2-24 years, including 42 children (26 girls, 16 boys, mean age 8.01 ± 5.69, range 2-18) with newly diagnosed coeliac disease (CD) (group I), 60 patients (39 females, 21 males, mean age 15.68 ± 4.74, range 5-24) with CD recognized at least 3 years before entering the study, non-compliants with gluten-free diet (group II) and 67 children (34 girls, 33 boys, mean age 6,28± 4.48, range 2-16) suspected of malabsorption, in whom diagnosis of CD had been excluded.

Methods: Serum samples were taken from all patients and tested for total IgA, anti-endomysial IgA (IgAEmA) or IgG autoantibodies (IgGEmA), only in cases with IgA deficiency, by indirect immunofluorescence method and anti-tTGIgA antibodies by ELISA.

Results: [Table: see text] Strong significant associations between anti-tTGIgA present in the serum and IgAEmA (Kendall τ 0.7748, p<0.0001) and good correlation between the levels of anti-tTGIgA and IgAEmA (r=0,488, p=0.001) were found in group I. We have not shown the relationship between the presence of both types of antibodies in patients of group II (Kendall τ 0.2102, p=0.0937). However, a good significant correlation between the levels of these parameters was observed (r=0,813, p<0,0001). Anti-tTGIgA concentration was nificantly higher in patients of group I compared to group II (38.35 U/ml v. 23.13 U/ml, p=0,0356). The sensitivity of anti- tTGIgA test in group I was 88.1%, in group II - 91.7% while specificity reached 97%.

Conclusions: Determination of anti-tTGIgA shows high sensitivity (88.1%) and specificity (97%) for the detection of coeliac disease. This test can be used alternatively with the immunofluorescent IgAEmA in diagnosis of coeliac disease, and also as a marker of compliance with gluten-free diet. However, both IgAEmA and anti-tTGIgA tests do not reach 100% sensitivity and specificity for diagnosis and nitoring of celiac disease. Therefore small intestinal biopsy is still recommended as a ? gold standard?.

Keywords: anti-endomysial antibodies; anti-tissue transglutaminase antibodies; coeliac disease.

Figure 1.

Comparison between anti-tTGIgA in both groups of patients with coeliac disease