Autoantibodies to Tissue Transglutaminase in Sjögren's Syndrome and Related Rheumatic Diseases

LEEANNE M. LUFT, SUSAN G. BARR, LIAM O. MARTIN, EDWARD K.L. CHAN, and MARVIN J. FRITZLER

ABSTRACT.

Objective. Sjögren's syndrome (SS) has been reported in up to 15% of patients with biopsy proven celiac disease (CD). The diagnosis of CD in the setting of SS and other systemic rheumatic diseases can be difficult because they are often associated with a number of gastrointestinal symptoms and diseases. Although the diagnosis of CD is often confirmed by a small bowel biopsy, marker autoantibodies directed against the endomysium of transitional epithelium (EMA) and tissue transglutaminase (tTG) are highly correlated with biopsy-proven disease and serve as a valuable screening test. We used an IgA-anti-tissue transglutaminase antibody (anti-tTG) ELISA to assess the prevalence of anti-tTG in an unselected cohort of patients with SS and other systemic rheumatic diseases.

Methods. Sera from 50 patients with SS, 50 with systemic lupus erythematosus (SLE), 50 with rheumatoid arthritis (RA), 30 with systemic sclerosis (SSc), and 50 healthy controls were tested for autoantibodies to tTG. A comparison group of 40 sera from patients with biopsy-confirmed CD was also included. IgA anti-tTG was measured by a commercially available ELISA kit (Inova, San Diego, CA) that employs purified tTG.

Results. Six of the 50 (12%) IgA sufficient SS patients had anti-tTG compared to 2 (4%) normal sera, 3 (6%) SLE, 2 (7%) SSc, and 1 (2%) RA. By comparison, in the CD cohort, 33 (83%) had anti-tTG. Five of 6 SS patients with anti-tTG had symptoms, signs, or small bowel biopsy findings consistent with a diagnosis of CD. IgA anti-tTG and EMA were accompanied by other IgA autoantibodies in SS sera.

Conclusion. Anti-tTG ELISA is a reliable method to indicate a coexisting diagnosis of CD in patients with SS. Interestingly, the frequency of false positive tTG tests in any of the systemic rheumatic diseases is not significantly greater than in controls. Further, our study shows that anti-tTG is more prevalent in SS than in other systemic rheumatic diseases. The tTG ELISA may be used as a screening test to identify patients with SS who are at risk and require further evaluation for the presence of CD. (J Rheumatol 2003;30:2613-9)

Key Indexing Terms:

SJÖGREN'S SYNDROME
TISSUE TRANSGLUTAMINASE
ENDOMYSIUM ANTIBODY
DIAGNOSIS
CELIAC DISEASE

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From the Department of Medicine, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada and the Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA.

Supported by the John Zabawski Research Fund at the University of Calgary.

L.M. Luft, BSc; S.G. Barr, MD; L.O. Martin, MD; M.J. Fritzler, PhD, MD, Faculty of Medicine, University of Calgary; E.K.L. Chan, PhD, College of Dentistry, University of Florida.

Address reprint requests to Dr. M.J. Fritzler, Faculty of Medicine, 3330 Hospital Dr. NW, Calgary, AB Canada T2N 4N1. E-mail: fritzler@ucalgary.ca

Submitted February 17, 2003; revision accepted May 6, 2003.

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