Diagnostic efficacy of the ELISA test for the detection of deamidated anti-gliadin peptide antibodies in the diagnosis and monitoring of celiac disease.
OBJECTIVE
We evaluated the diagnostic performance of an ELISA test for anti-gliadin IgA and IgG antibodies, which uses synthetic deamidated gliadin peptides (anti-gliadin antibodies, AGAs) as coating; the results were compared with a test that uses extracted gliadin (AGAe).


METHODS
The study was conducted on the sera of 144 patients suffering from celiac disease (CD), including 20 patients with IgA deficiency and 9 who were following a gluten-free diet (GFD), and 129 controls.


RESULTS
In the 115 CD patients (without IgA deficiency), the sensitivity of AGAe IgA and IgG was 32.2 and 60.9%, whereas that of AGAs IgA and IgG was 59.1 and 72.2%. The specificity for AGAe IgA and IgG, and AGAs IgA and IgG was 93.8 and 89.9%, and 96.9% and 99.2%, respectively. Of the 20 patients with CD and IgA deficiency, 7 tested positive for AGAe IgG and 14 for AGAs IgG. The test using deamidated gliadin peptides performed better in terms of sensitivity and specificity than the AGA tests with extracted antigen.


CONCLUSIONS
The very high specificity of the AGAs IgG test (99.2%) also suggests that patients who test positive with this assay require a thorough followup, even if the anti-tissue transglutaminase antibodies (anti-tTG) and anti-endomysial autoantibodies (EMA) assays are negative.
Tonutti
Elio
E
Immunopatologia e Allergologia Azienda Ospedaliero-Universitaria S. Maria della Misericordia di Udine, Udine, Italy. tonutti.elio@aoud.sanita.fvg.it
Visentini
Daniela
D
Picierno
Alessia
A
Bizzaro
Nicola
N
Villalta
Danilo
D
Tozzoli
Renato
R
Kodermaz
Graziano
G
Carroccio
Antonio
A
Iacono
Giuseppe
G
Teresi
Saverio
S
La Chiusa
Stella Maria
SM
Brusca
Ignazio
I
D000293:Adolescent; D000328:Adult; D000368:Aged; D000906:Antibodies / Q000097:blood* / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood / Q000276:immunology; D016022:Case-Control Studies; D002446:Celiac Disease / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D005903:Gliadin / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000276:immunology; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012698:Serologic Tests; D011503:Transglutaminases / Q000276:immunology; D055815:Young Adult
D000906:Antibodies; D001323:Autoantibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D010455:Peptides; D005903:Gliadin; D011503:Transglutaminases