Objective. To investigate functional properties of the germinal center (GC)-like structures observed in salivary glands of patients with Sjögren's syndrome (SS) and to determine the frequency with which such structures develop.Methods. Hematoxylin and eosin-stained sections from 165 minor salivary gland biopsy samples were screened for GC-like structures. Expression of markers for GCs (CD3, CD20, Ki-67, CD35, CD31), adhesion molecules (intercellular adhesion molecule 1, lymphocyte function-associated antigen 1, vascular cell adhesion molecule 1, very late activation antigen 4), chemokines (CXCL13, CCL21, CXCL12), and production of autoantibodies (anti-Ro/SSA and anti-La/SSB) was investigated by immunohistochemistry. Apoptosis was investigated by TUNEL staining.Results. GC-like structures were observed in 28 of 165 patients (17%). When GCs were defined as T and B cell aggregates with proliferating cells with a network of follicular dendritic cells and activated endothelial cells, such microenvironments were found in all patients in whom structures with GC-like morphology were observed. The defined microenvironments were not found in patients without apparent GC-like structures. The GCs formed within the target tissue showed functional features with production of autoantibodies (anti-Ro/ SSA and anti-La/SSB) and apoptotic events (by TUNEL staining), and the local production of anti-Ro/SSA and anti-La/SSB autoantibodies was significantly increased (P ‫؍‬ 0.04) in patients with GC development.Conclusion. Lymphoid neogenesis and functional ectopic GC formation take place in salivary glands of a subset of patients with SS. Our data suggest that the ectopic secondary lymphoid follicles contain all elements needed for driving the autoimmune response. Our findings underscore a key role for the target organ in recruitment of inflammatory cells and propagation of the disease process.

ObjectiveThe development of non-Hodgkin's lymphoma (NHL) confers a high risk of mortality in primary Sjögren's syndrome (pSS) patients, but the sensitivity and specificity of proposed lymphoma predictors are insufficient for practical use. The performance of lymphoid organisation in the form of germinal centre (GC)-like lesions was evaluated in labial salivary gland biopsies taken at pSS diagnosis as a potential lymphoma-predicting biomarker.MethodsLabial salivary gland tissue biopsies available from two Swedish pSS research cohorts (n=175) were re-evaluated by light microscopy in a blind study in order to identify GC-like structures as a sign of ectopic lymphoid tissue formation and organisation. A linkage study was performed with the Swedish Cancer Registry for lymphoma identification. The risk of developing NHL in GC-positive patients in comparison with GC-negative patients was evaluated using Kaplan–Meier statistics and log-rank test. Associations between GC-like structures and clinical and/or laboratory disease markers were also determined using χ2 or Fisher's exact tests.ResultsAt diagnosis, 25% of pSS patients had GC-like structures in their salivary glands. Seven of the 175 patients studied (14% GC+ and 0.8% GC−) developed NHL during 1855 patient-years at risk, with a median onset of 7 years following the initial diagnostic salivary gland biopsy. Six of the seven patients had GC-like structures at diagnosis; the remaining patient was GC negative at the time of diagnosis (p=0.001).ConclusionsThe detection of GC-like structures by light microscopy in pSS diagnostic salivary biopsies is proposed as a highly predictive and easy-to-obtain marker for NHL development. This allows for risk stratification of patients and the possibility to initiate preventive B-cell-directed therapy.

B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) are members of the tumour necrosis factor superfamily. We have examined circulating BAFF and APRIL in relation to serological deviations and lymphoid organization in the salivary glands of the chronic, autoimmune disorder Sjögren's syndrome. Lymphoid organization in the shape of ectopic germinal centers were detected in 33 of 130 consecutive minor salivary gland biopsies and coincided with increased focus score and elevated levels of serum IgG. Follicular dendritic cell networks, proliferation of mononuclear cells and altered B/T cell ratio also separated the two subgroups. Serum levels of sBAFF and sAPRIL were increased in Sjögren's syndrome compared to healthy blood donors, especially in anti-Ro/La+ patients. Though the differences could not be related to germinal center formation, positive correlations between serum levels of sBAFF and sAPRIL, focus score and IgG denotes their possible role in the disease progression of primary Sjögren's syndrome.

Objective. To characterize the chronologic disease course and possible interrelationships between salivary gland inflammation, hyposalivation, and cytokine levels in NOD mice, a model for Sjögren's syndrome (SS).Methods. NOD mice of different ages were used to mimic different disease stages of SS. Histopathologic findings and rates of salivary secretion were compared between 8-week-old, 17-week-old, and 24-week-old female mice. In addition, 10 cytokines were analyzed in serum and saliva obtained from NOD and BALB/c mice.Results. In NOD mice, the salivary flow rate did not change between 8 weeks and 17 weeks of age, while a significant decrease in the salivary flow rate occurred between 17 weeks and 24 weeks of age (P < 0.001). In contrast, significant histopathologic changes in the salivary glands occurred before 17 weeks of age. Chronic inflammatory cell infiltrates were characterized by T and B cell infiltration. Interestingly, in one-third of the mice, proliferating cells were observed in the focal infiltrates. Significant changes in the levels of interleukin-2 (IL-2), IL-5, and granulocyte-macrophage colony-stimulating factor in serum, and in the levels of IL-4 and tumor necrosis factor ␣ (TNF␣) in saliva occurred contemporarily with the decrease in salivary flow. Correlation analyses revealed a negative association between salivary secretion and the levels of IL-4, interferon-␥, and TNF␣ in saliva obtained from NOD mice, while the correlation with inflammatory changes in the glands was consistently weak.Conclusion. Consistent with previous findings, our results indicate at least 2 phases of SS-like disease in NOD mice. Hyposalivation was preceded by inflammatory changes in the salivary glands, whereas abrupt changes in secretion occurred without significant progression of inflammation. Changes in cytokine levels are an indication of the mechanisms involved in the adaptive immune response in the transition from early to overt disease.