Serological implications of germinal center-like structures in primary Sjögren's syndrome

To determine serological implications of germinal center (GC)-like structures in primary Sjögren's syndrome (pSS).

Retrospectively, minor salivary gland biopsies (n = 269) with focal lymphoid aggregates corresponding to focus score > 1 were evaluated for the presence of GC-like morphology. Relevant clinical information was obtained from medical records.

Of 269 patients, 169 fulfilled the American-European criteria for pSS. GC-like features were observed in 47/169 (28%) biopsies. In the majority of cases, GC-like lesions were confirmed by CD21-positive follicular dendritic cell networks. Mean inflammatory focus score was significantly higher in GC-positive compared to GC-negative samples (p < 0.001). GC-positive patients had lower mean salivary secretion (p < 0.001) and a higher frequency of patients with unstimulated salivary secretion < or = 1.5 ml/15 min (p < 0.01). In addition, elevated titers of rheumatoid factor, serum anti-Ro/SSA and anti-La/SSB (p < 0.05), and IgG levels > or = 15.3 g/l (p < 0.05) were more common in GC-positive compared to GC-negative. Enlarged salivary glands were observed in 46/163 (28%) patients, but could not be linked to either presence or absence of GC-like features.

Inflammatory infiltrates with GC-like morphology were observed in 28% of the investigated patients with pSS, and was particularly noted in patients with higher focus score. The observed serological aberrations in patients with ectopic GC-like structures in the minor salivary glands warrant further prospective studies.