Background/Purpose:
To determine IgG4 serum levels in a cohort of patients fulfilling the classification criteria for primary Sjogren’s syndrome (pSS) and to explore whether they associate with distinct clinical, serological and histopathological parameters.
Methods:
IgG4 levels were measured by nephelometry in sera from 140 consecutive pSS patients and 45 healthy controls of similar age and sex distribution. Immunohistochemical IgG4 analysis was performed on paraffin-embedded salivary gland tissues from patients with high and low IgG4 serum levels.
Results:
Raised IgG4 serum levels defined as higher than 135mg/dl were detected in 8 out of 81 pSS patients analyzed (9.9%) (“High-IgG4” group) and in none of controls (p=0.05). Compared to their counterparts with normal IgG4 serum levels, the “High-IgG4” subset is characterized by significantly increased prevalence of IgG4-related features such as autoimmune pancreatitis, cholangitis and interstitial nephritis (p=0.006), lower rates of ANA (p=0.05) and anti-Ro/SSA (p=0.05) positivity. Although not statistically significant, sicca features and anti-La/SSB positivity occurred less frequently in the “High-IgG4” group. Multivariate logistic regression analysis revealed interstitial nephritis (p=0.048), autoimmune cholangitis (p=0.012) or pancreatitis (p=0.027) and absence of ANA (p=0.005) as independent predictors of IgG4 serum levels. Positive staining for IgG4+ plasma cells was detected in one out of four available MSG biopsies in the “High-IgG4” group but in none of the control patients with normal IgG4 serum levels. Analysis of the whole group is in process.
Conclusion:
Raised IgG4 levels occur approximately in 10% of patients with pSS and characterize a subgroup with high prevalence of IgG4-related clinical and serological features. Whether these patients represent a distinct pSS subset or a misclassified IgG4-Related (IgG4-RD) disease group remains to be defined.
Disclosure:
C. P. Mavragani,
None;
G. Fragoulis,
None;
D. Rontogianni,
None;
M. Kanariou,
None;
H. M. Moutsopoulos,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/elevated-igg4-serum-levels-among-primary-sjogrens-syndrome-patients-do-they-unmask-underlying-igg4-related-disease/