Accuracy of testing for antibodies to synthetic gliadin-related peptides in celiac disease.
OBJECTIVE
Our aim was to explore the diagnostic value of a newly developed synthetic peptide antibody assay addressing specific synthetic gliadin-derived deamidated peptides (AGA II) for the diagnosis of celiac disease (CD).


METHODS
We assayed serum samples obtained prospectively at diagnosis from a population of 92 consecutive adult patients with CD and 113 non-CD controls. Patients were reevaluated after 6 months (n = 56) and 1 year (n = 20) of treatment. All patients and controls underwent intestinal biopsy and a set of CD-related serology tests. A newly developed enzyme-linked immunosorbent assay (ELISA) for detecting IgA and IgG antibodies against synthetic deamidated gliadin epitopes was used.


RESULTS
At diagnosis, sensitivity and specificity were 94.6% and 99.1% for AGA II IgA and 92.4% and 100% for AGA II IgG. Absolute values and the proportion of positive samples for both antibodies were significantly reduced at 6 months (P < .0000) and 1 year (P < .001) after initiation of a gluten-free diet. Compared with conventional AGA, the peptide antibodies had greater sensitivity, specificity, positive and negative predictive values, accuracy, and likelihood ratios. Compared with antitissue transglutaminase antibodies, AGA II had similar sensitivity but greater specificity and predictive values, better likelihood ratios, and an excellent agreement (kappa statistic = .92).


CONCLUSIONS
This study assessed the value of an ELISA assay in detecting antibodies to gliadin-related peptides. This assay appears to be a reliable tool for diagnosing CD and suggests promising accuracy that may be very useful in clinical practice.
Sugai
Emilia
E
Small Bowel Diseases Clinic, Division of Pathology, Department of Medicine, Dr. Carlos Bonorino Udaondo Hospital of Gastroenterology, Buenos Aires, Argentina.
Vázquez
Horacio
H
Nachman
Fabio
F
Moreno
María Laura
ML
Mazure
Roberto
R
Smecuol
Edgardo
E
Niveloni
Sonia
S
Cabanne
Ana
A
Kogan
Zulema
Z
Gómez
Juan C
JC
Mauriño
Eduardo
E
Bai
Julio C
JC
D000293:Adolescent; D000328:Adult; D000368:Aged; D002446:Celiac Disease / Q000097:blood / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005903:Gliadin / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012698:Serologic Tests
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D005903:Gliadin