IgA isotyping of antigliadin antibodies. A possible clue for a less invasive diagnosis of coeliac disease

Humoral immune responses of workers occupationally exposed to wheat flour

Wheat flour is a complex organic dust likely to induce immune responses when inhaled in work environment conditions. We compared the humoral status of 159 exposed workers from 11 flour mills and one industrial bakery with that of 41 workers from a salt factory. IgG, IgA, and IgM levels of antibodies to whole flour and to gliadin were assayed using ELISA tests in serum and saliva samples. Serum levels of IgG and IgA to both antigens were significantly higher (p < 0.0001) in occupationally exposed workers. Exposed workers had significantly higher levels of salivary IgG (p = 0.005) and IgA (p < 0.0001) to whole flour and of salivary IgG (p = 0.0005) to gliadin. In both groups, similar levels of anti-gliadin salivary IgA antibodies were observed. These data suggest that occupational exposure to wheat flour triggers specific immune responses, most likely through stimulation of the mucosal immune system. The presence of significant levels of serum antibodies, however, indicates that a systemic immunologic response is also present among exposed individuals.

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.