Drs. Mavragani and Fragoulis contributed equally to this work.
Elevated IgG4 Serum Levels Among Primary Sjögren's Syndrome Patients: Do They Unmask Underlying IgG4-Related Disease?
Article first published online: 22 APR 2014
Copyright © 2014 by the American College of Rheumatology
Arthritis Care & Research
Volume 66, Issue 5, pages 773–777, May 2014
How to Cite
Mavragani, C. P., Fragoulis, G. E., Rontogianni, D., Kanariou, M. and Moutsopoulos, H. M. (2014), Elevated IgG4 Serum Levels Among Primary Sjögren's Syndrome Patients: Do They Unmask Underlying IgG4-Related Disease?. Arthritis Care Res, 66: 773–777. doi: 10.1002/acr.22216
- Issue published online: 22 APR 2014
- Article first published online: 22 APR 2014
- Accepted manuscript online: 21 OCT 2013 11:56AM EST
- Manuscript Accepted: 15 OCT 2013
- Manuscript Received: 2 MAY 2013
To determine IgG4 levels in a cohort of consecutive patients with primary Sjögren's syndrome (SS) and other autoimmune diseases and explore whether they associate with distinct clinical, serologic, and histopathologic features.
Serum IgG4 levels were measured in 133 primary SS patients and 49 healthy donors (HDs). Seventy-four lupus and 54 rheumatoid arthritis (RA) patients served as disease controls. Immunohistochemical IgG4 analysis was performed in paraffin-embedded minor salivary gland (MSG) tissues.
Raised IgG4 serum levels (>135 mg/dl) were detected in 10 (7.5%) of 133 primary SS patients (high-IgG4 group), in 8 (10.8%) of 74 lupus patients, in 7 (12.9%) of 54 RA patients, and in 1 (2%) of 49 HDs. Compared to the normal-IgG4 (<135 mg/dl) primary SS group, high-IgG4 patients exhibited increased prevalence of IgG4-related features (autoimmune cholangitis, autoimmune pancreatitis, and interstitial nephritis), lower rates of antinuclear antibody positivity, and higher IgG2 and IgE levels. Positive staining for IgG4+ plasma cells with an IgG4:IgG ratio ≥40% was detected in 3 of 6 available MSG tissues in the high-IgG4 group. Criteria of possible or definite IgG4-related disease (IgG4-RD) were fulfilled by 10 (7.5%) of 133 of our primary SS cohort.
Raised IgG4 serum levels were detected in 7.5% of primary SS patients in association with IgG4RD–reminiscent clinical, serologic, and histopathologic features. Whether this high-IgG4 primary SS group represents a misclassified IgG4-RD group or a distinct primary SS subtype remains to be further explored in future studies.