Testing for IgG class antibodies in celiac disease patients with selective IgA deficiency. A comparison of the diagnostic accuracy of 9 IgG anti-tissue transglutaminase, 1 IgG anti-gliadin and 1 IgG anti-deaminated gliadin peptide antibody assays.
BACKGROUND
To evaluate the diagnostic characteristics of commercially available IgG anti-tTG assays in selective IgA deficiency (SIgAD), we tested different IgG anti-tTG methods and compared the results with those obtained from two other tests: one for IgG anti-gliadin (AGA) and one for IgG to deaminated gliadin peptides (DGP).


METHODS
20 CD patients with SIgAD and 113 controls (9 patients with SIgAD without CD; 54 patients with chronic liver disease; 50 healthy subjects) were tested with 9 IgG anti-tTG assays (2 of which are enriched with gliadin peptides), one IgG AGA assay and one IgG anti-DGP assay.


RESULTS
Using optimal cutoffs as determined by ROC curves, the sensitivity of IgG anti-tTG methods ranged from 75% (1 kit) to 95% (7 kits) and the specificity from 94% (1 kit) to 100% (5 kits). Sensitivity and specificity were 40% and 87% for IgG AGA, and 80% and 98% for IgG anti-DGP, respectively.


CONCLUSIONS
All IgG anti-tTG methods evaluated are reliable serologic assays for the diagnosis of CD in patients with SIgAD and perform better than the gliadin-based assays used in this study. The tests containing both tTG and gliadinic peptides are burdened by a lower specificity than the anti-tTG assays.
Villalta
Danilo
D
Immunologia Clinica e Virologia, AO S Maria degli Angeli, Via Montereale 24, Pordenone, Italy. danilo.villalta@aopn.fvg.it
Alessio
Maria Grazia
MG
Tampoia
Marilina
M
Tonutti
Elio
E
Brusca
Ignazio
I
Bagnasco
Marcello
M
Pesce
Giampaola
G
Stella
Sergio
S
Bizzaro
Nicola
N
D000293:Adolescent; D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D002446:Celiac Disease / Q000175:diagnosis / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005903:Gliadin / Q000276:immunology*; D006801:Humans; D017098:IgA Deficiency / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D011503:Transglutaminases / Q000276:immunology*
D001323:Autoantibodies; D007074:Immunoglobulin G; D011933:Reagent Kits, Diagnostic; D005903:Gliadin; D011503:Transglutaminases