Germinal Centres in Primary Sjögren's Syndrome Indicate a Certain Clinical Immunological Phenotype

Abstract

Ectopic germinal centers (GCs) can be detected in the salivary glands of approximately 1/5 of patients with Sjögren's syndrome (SS) and appear in both primary and secondary SS. Previously, ectopic GC have been associated with increased local autoantibody production. The aim of this study was to determine whether GC in primary Sjögren's syndrome (pSS) defines a distinct seroimmunological phenotype. Retrospectively, a material of 130 haematoxylin and eosin‐stained paraffin‐embedded tissue sections of minor salivary gland tissue from patients with pSS was morphologically screened for the presence of ectopic GC. GC‐like lesions were detected in 33/130 (25%) of the pSS patients. Seventy‐two pSS patients lacking these structures (GC‐) were randomly selected for comparison. Focus score was significantly increased in the GC+ patients compared to the GC– patients (P = 0.035). In the GC+ group, 54.5% of the patients presented with anti‐Ro/SSA compared to 43.7% in the GC– group. Anti‐La/SSB was detected in 31.3% of the GC+ patients compared to 25.7% of the GC– patients. Sixty‐one percentage of GC+ patients presented with increased levels of IgG, a nonsignificant difference when compared to 39.4% in the GC– patients (P = 0.089). Levels of RF, ANA, ENA, IgM and IgA were similar in both patient groups, as were ESR and CRP. In conclusion, patients with ectopic GC have a higher focus score and more often present with autoantibodies and increased levels of IgG compared to pSS patients with regular focal infiltration (GC–). Our findings may indicate a certain seroimmunological phenotype and warrant for further prospective studies.