Abnormal B cell differentiation in primary Sjögren's syndrome results in a depressed percentage of circulating memory B cells and elevated levels of soluble CD27 that correlate with Serum IgG concentration

Circulating immune markers and risks of non-Hodgkin lymphoma subtypes: A pooled analysis

Although prediagnostic circulating concentrations of the immune activation markers soluble CD27 (sCD27), sCD30 and chemokine ligand-13 (CXCL13) have been associated with non-Hodgkin lymphoma (NHL) risk, studies have been limited by sample size in associations with NHL subtypes. We pooled data from eight nested case-control studies to investigate subtype-specific relationships for these analytes. Using polytomous regression, we calculated odds ratios (ORs) with 95% confidence intervals (CIs) relating study-specific analyte tertiles to selected subtypes vs controls (n = 3310): chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL; n = 623), diffuse large B cell lymphoma (DLBCL; n = 621), follicular lymphoma (FL; n = 398), marginal zone lymphoma (MZL; n = 138), mantle cell lymphoma (MCL; n = 82) and T cell lymphoma (TCL; n = 92). We observed associations with DLBCL for elevated sCD27 [OR for third vs first tertile (ORT3 ) = 2.2, 95% CI = 1.6-3.1], sCD30 (ORT3  = 2.0, 95% CI = 1.6-2.5) and CXCL13 (ORT3  = 2.3, 95% CI = 1.8-3.0). We also observed associations with sCD27 for CLL/SLL (ORT3  = 3.3, 95% CI = 2.4-4.6), MZL (ORT3  = 7.7, 95% CI = 3.0-20.1) and TCL (ORT3  = 3.4, 95% CI = 1.5-7.7), and between sCD30 and FL (ORT3  = 2.7, 95% CI = 2.0-3.5). In analyses stratified by time from phlebotomy to case diagnosis, the sCD27-TCL and all three DLBCL associations were equivalent across both follow-up periods (<7.5, ≥7.5 years). For other analyte-subtype comparisons, associations were stronger for the follow-up period closer to phlebotomy, particularly for indolent subtypes. In conclusion, we found robust evidence of an association between these immune markers and DLBCL, consistent with hypotheses that mechanisms related to immune activation are important in its pathogenesis. Our other findings, particularly for the rarer subtypes MZL and TCL, require further investigation.

Alterations in B- and circulating T-follicular helper cell subsets in immune thrombotic thrombocytopenic purpura

Abnormal B-cell phenotype in acute iTTP with decreased transitional and post–germinal center memory cells and increased plasmablasts.

Decreased total and PD1⁺ circulating T-follicular helper cells and changes in B-cell CD80 expression suggest altered B- and T-cell interactions.

T follicular helper (Tfh) cells regulate development of antigen-specific B-cell immunity. We prospectively investigated B-cell and circulating Tfh (cTfh) cell subsets in 45 patients with immune thrombotic thrombocytopenic purpura (iTTP) at presentation and longitudinally after rituximab (RTX). B-cell phenotype was altered at acute iTTP presentation with decreased transitional cells and post–germinal center (post-GC) memory B cells and increased plasmablasts compared with healthy controls. A higher percentage of plasmablasts was associated with higher anti-ADAMTS13 IgG and lower ADAMTS13 antigen levels. In asymptomatic patients with ADAMTS13 relapse, there were increased naïve B cells and a global decrease in memory subsets, with a trend to increased plasmablasts. Total circulating Tfh (CD4⁺CXCR5⁺) and PD1⁺ Tfh cells were decreased at iTTP presentation. CD80 expression was decreased on IgD⁺ memory cells and double-negative memory cells in acute iTTP. At repopulation after B-cell depletion in de novo iTTP, post-GC and double-negative memory B cells were reduced compared with pre-RTX. RTX did not cause alteration in cTfh cell frequency. The subsequent kinetics of naïve, transitional, memory B cells and plasmablasts did not differ significantly between patients who went on to relapse vs those who remained in remission. In summary, acute iTTP is characterized by dysregulation of B- and cTfh cell homeostasis with depletion of post-GC memory cells and cTfh cells and increased plasmablasts. Changes in CD80 expression on B cells further suggest altered interactions with T cells.

Utility of lymphocyte phenotype profile to differentiate primary Sjögren syndrome from Sicca syndrome

BACKGROUND

blood B cell profile has been proposed to have diagnostic utility in primary Sjögren syndrome (pSS), but the potential utility of advanced lymphocyte profiling to differentiate between pSS and Sicca syndrome has not been fully investigated.

METHODS

distribution of peripheral lymphocyte subpopulations was analysed by flow cytometry in 68 patients with pSS, 26 patients with Sicca syndrome and 23 healthy controls. The ability to discriminate between pSS and Sicca syndrome was analysed using the area under the curve (AUC) of the receiver operating characteristic curve of the different lymphocyte subsets.

RESULTS

the ratio between naïve/memory B cell proportions showed an AUC of 0.742 to differentiate pSS and Sicca syndrome, with a sensitivity of 76.6% and a specificity of 72% for a cut-off value of 3.4. The ratio of non-switched memory B cells to activated CD4+ T cells percentage (BNSM/CD4ACT) presented the highest AUC (0.840) with a sensitivity of 83.3% and specificity of 81.7% for a cut-off value < 4.1. To differentiate seronegative pSS patients from Sicca patients the BNSM/CD4ACT ratio exhibited an AUC of 0.742 (sensitivity 75%, specificity 66.7%, cut-off value < 4.4), and the number of naïve CD4 T cells had an AUC of 0.821 (sensitivity 76.9%, specificity 88.9%, cut-off value < 312/mm3).

CONCLUSION

patients with pSS show a profound imbalance in the distribution of circulating T and B lymphocytes subsets. The ratio BNSM/CD4ACT is useful to discriminate between pSS and Sicca syndrome.

New frontiers in precision medicine for Sjogren's syndrome

Introduction: Sjögren's syndrome is a unique systemic autoimmune disease, placed in the center of systemic autoimmunity and at the crossroads of autoimmunity and lymphoproliferation. The diverse clinical picture of the disease, the inefficacy of current biologic treatments, and the co-existence with lymphoma conferring to the patients' morbidity and mortality force the scientific community to review disease pathogenesis and reveal the major implicated cellular and molecular elements.Areas covered: Biomarkers for early diagnosis, prediction, stratification, monitoring, and targeted treatments can serve as a tool to interlink and switch from the clinical phenotyping of the disease into a more sophisticated classification based on the underlying critical molecular pathways and endotypes. Such a transition may define the establishment of the so-called precision medicine era in which patients' management will be based on grouping according to pathogenetically related biomarkers. In the current work, literature on Sjogren's syndrome covering several research fields including clinical, translational, and basic research has been reviewed.Expert opinion: The perspectives of clinical and translational research are anticipated to define phenotypic clustering of high-risk pSS patients and link the clinical picture of the disease with fundamental molecular mechanisms and molecules implicated in pathogenesis.

B cell dysregulation in primary Sjögren's syndrome: A review

Primary Sjögren’s syndrome is a chronic autoimmune disorder of unknown etiology and is characterized by progressive focal lymphocytic infiltration of the lacrimal and salivary glands. Comparison of B cell subsets from the peripheral blood and salivary glands of patients with primary Sjögren’s syndrome and those from healthy individuals shows dysregulation and derangement of B cell subsets in both peripheral circulation and in inflamed glandular tissues. This dysregulation is expressed as a decrease in the percentage of CD27+ memory B cells in peripheral blood and an increase in the CD27+ memory B cells in the affected glands. Further, the overall percentage of long-lived autoantibodies-producing plasma cells within the affected glands is increased. In the last two decades, several studies have shown growing evidences that B cells play multiple roles in primary Sjögren’s syndrome pathophysiology, and that dysregulation of these cells may actually play a central role in the disease development.

B cells in Sjögren's syndrome: from pathophysiology to therapeutic target

Biological abnormalities associated with B lymphocytes are a hallmark of patients with primary Sjögren's syndrome. Those patients present abnormal distribution of B lymphocytes in peripheral blood and B cells in exocrine glands. B cells produce auto-antibodies, cytokines and present antigens but can also suppressive functions. In this review, we will summarize current knowledge on B cells in primary Sjögren's syndrome patients, demonstrate their critical role in the immunopathology of the disease and describe the past and current trials targeting B cells.

Current concepts on Sjögren's syndrome - classification criteria and biomarkers

Sjögren's syndrome is a lymphoproliferative disease with autoimmune features characterized by mononuclear cell infiltration of exocrine glands, notably the lacrimal and salivary glands. These lymphoid infiltrations lead to dryness of the eyes (keratoconjunctivitis sicca), dryness of the mouth (xerostomia), and, frequently, dryness of other surfaces connected to exocrine glands. Sjögren's syndrome is associated with the production of autoantibodies because B-cell activation is a consistent immunoregulatory abnormality. The spectrum of the disease extends from an organ-specific autoimmune disorder to a systemic process and is also associated with an increased risk of B-cell lymphoma. Current treatments are mainly symptomatic. As a result of the diverse presentation of the syndrome, a major challenge remains to improve diagnosis and therapy. For this purpose an international set of classification criteria for primary Sjögren's syndrome has recently been developed and validated and seems well suited for enrolment in clinical trials. Salivary gland biopsies have been examined and histopathology standards have been developed, to be used in clinical trials and patient stratification. Finally, ultrasonography and saliva meet the need of non-invasive imaging and sampling methods for discovery and validation of disease biomarkers in Sjögren's syndrome.

Tertiary Lymphoid Structures: Autoimmunity Goes Local

Tertiary lymphoid structures (TLS) are frequently observed in target organs of autoimmune diseases. TLS present features of secondary lymphoid organs such as segregated T and B cell zones, presence of follicular dendritic cell networks, high endothelial venules and specialized lymphoid fibroblasts and display the mechanisms to support local adaptive immune responses toward locally displayed antigens. TLS detection in the tissue is often associated with poor prognosis of disease, auto-antibody production and malignancy development. This review focuses on the contribution of TLS toward the persistence of the inflammatory drive, the survival of autoreactive lymphocyte clones and post-translational modifications, responsible for the pathogenicity of locally formed autoantibodies, during autoimmune disease development.

Insights Into the Molecular Mechanisms of T Follicular Helper-Mediated Immunity and Pathology

T follicular helper (Tfh) cells play key role in providing help to B cells during germinal center (GC) reactions. Generation of protective antibodies against various infections is an important aspect of Tfh-mediated immune responses and the dysregulation of Tfh cell responses has been implicated in various autoimmune disorders, inflammation, and malignancy. Thus, their differentiation and maintenance must be closely regulated to ensure appropriate help to B cells. The generation and function of Tfh cells is regulated by multiple checkpoints including their early priming stage in T zones and throughout the effector stage of differentiation in GCs. Signaling pathways activated downstream of cytokine and costimulatory receptors as well as consequent activation of subset-specific transcriptional factors are essential steps for Tfh cell generation. Thus, understanding the mechanisms underlying Tfh cell-mediated immunity and pathology will bring into spotlight potential targets for novel therapies. In this review, we discuss the recent findings related to the molecular mechanisms of Tfh cell differentiation and their role in normal immune responses and antibody-mediated diseases.

T follicular-like helper cells in the peripheral blood of patients with primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease characterized by exocrine gland dysfunction, mainly causing sicca symptoms. B cells have a prominent role in SS, and the T follicular helper (TFH ) cells provide B cells with survival and specialization signals in germinal centres. Here, we investigate peripheral TFH cells in pSS. Sixteen pSS patients and healthy controls were enrolled in the study, with 13 women and 3 men in each group. Whole blood was collected and separated into PBMC and plasma, followed by cryopreservation. Plasma samples were analysed for Ro52, Ro60 and La48 autoantibodies by indirect ELISA. For flow cytometric analysis, we defined 4 subsets of TFH-like cells within the CD3+ CD4+ CXCR5+ population, namely the ICOS- PD-1- , ICOS- PD-1+ , ICOS+ PD-1- and ICOS+ PD-1+ ("TFH") cells. We also investigated 4 CD19+ B cell subsets, the CD20+ CD27+ CD38- memory B cells, CD20+ CD27+ CD38+ memory B cells, CD20- CD27+ CD38++ CD138- plasmablasts and CD20- CD27+ CD38++ CD138+ plasma cells. We observed higher fractions of ICOS+ PD-1- cells, ICOS+ PD-1+ ("TFH ") cells and plasmablasts in pSS patients compared to controls, and lower frequencies of both types of memory B cells. The number of TFH cells correlated positively with the levels of plasmablasts and plasma cells in the pSS patients, but not in the controls. The pSS patients were stratified according to Ro52/Ro60/La48 serology, and a positive association was found between autoantibody levels and increased level of TFH cells, plasmablasts and plasma cells and lowered levels of memory B cells. We observed a higher response to Ro/La stimulation in pSS patients compared to controls of the memory B cells, although only significantly for the CD38- memory B cells. Overall, a pathological relation between the ICOS+ T follicular-like helper cells and B cells in pSS was observed, but further work should be conducted to explore their overall impact upon disease progression.

T-cell activation marker sCD27 is associated with clinically definite multiple sclerosis in childhood-acquired demyelinating syndromes

Background:

Cerebrospinal fluid (CSF) levels of T-cell activation marker soluble CD27 (sCD27) are associated with subsequent disease activity after a first attack of suspected MS in adults. The predictive value for disease course in children with acquired demyelinating syndromes (ADS) is unknown.

Objectives:

To assess the predictive value of sCD27 levels for clinically definite multiple sclerosis (CDMS) diagnosis in childhood ADS.

Methods:

Children <18 years with a first demyelinating event were prospectively included and followed. Soluble CD27 was determined in CSF using an enzyme-linked immunosorbent assay (ELISA). Cox regression analyses were used to calculate hazard ratios (HRs) for CDMS.

Results:

A total of 94 ADS children were included (ADS with encephalopathy (ADS+) n = 33 and ADS without encephalopathy (ADS–) n = 61). Of the 61 ADS– children, 21 (48%) were diagnosed with CDMS during follow-up. At baseline, sCD27 levels were higher in patients with a future CDMS diagnosis (n = 29) than in monophasic ADS+ (n = 30), monophasic ADS– (n = 28) and relapsing non-MS patients (n = 7; p < 0.001). In ADS– patients, sCD27 was associated with CDMS (HR = 1.8 per 100 U/mL increase in sCD27 levels, p = 0.031), after adjustments for age, oligoclonal bands and the presence of dissemination in space on baseline magnetic resonance imaging (MRI).

Conclusion:

CSF sCD27 levels at first attack of demyelination were associated with CDMS diagnosis in children. This makes sCD27 a potential clinically relevant quantitative marker when performing routine CSF diagnostics.

Diminished CXCR5 expression in peripheral blood of patients with Sjögren's syndrome may relate to both genotype and salivary gland homing

Genetic investigations of Sjögren's syndrome (SS) have identified a susceptibility locus at p23.3 of chromosome 11, which contains the CXCR5 gene. C-X-C motif chemokine receptor 5 (CXCR5) is a chemokine receptor expressed on B and T cell subsets, and binds the chemotactic ligand C-X-C motif chemokine ligand 13 (CXCL13). In this study we aimed to link the genetic association with functional effects and explore the CXCR5/CXCL13 axis in SS. Expression quantitative trait loci analysis of the 11q23.3 locus was performed using B cell mRNA expression data from genotyped individuals. Lymphocyte surface markers were assessed by flow cytometry, and CXCL13 levels by a proximity extension assay. CXCR5+ and CXCL13+ cells in minor salivary glands were detected using immunohistochemistry. Our results demonstrated that SS-associated genetic polymorphisms affected the expression of CXCR5 (P < 0·01). Notably, a decreased percentage of CXCR5+ cells, with lower CXCR5 expression, was observed for most circulating B and T cell subsets in SS patients, reaching statistical significance in CD19+ CD27+ immunoglobulin (Ig)D+ marginal zone (P < 0·001), CD19+ CD27+ IgD- memory (P < 0·05) and CD27-IgD double-negative (P < 0·01) B cells and CD4+ CXCR3- CCR6+ Th17 cells (P < 0·05). CXCL13 levels were increased in patient plasma (P < 0·001), and immunohistochemical staining revealed expression of CXCL13 and higher numbers of CXCR5+ cells (P < 0·0001) within focal infiltrates and interstitially in salivary glands of SS patients. In conclusion, we link a genetic susceptibility allele for SS to a functional phenotype in terms of decreased CXCR5 expression. The decrease of CXCR5+ cells in circulation was also related to homing of B and T cells to the autoimmune target organ. Therapeutic drugs targeting the CXCR5/CXCL13 axis may be useful in SS.

Increased proportion of a CD38highIgD+ B cell subset in peripheral blood is associated with clinical and immunological features in patients with primary Sjögren's syndrome

We investigated the correlation between the increased proportion of peripheral B cell subsets and clinical and immunological features in primary Sjögren's syndrome (pSS). We found that the proportion of CD19⁺ B cells was significantly increased in pSS as compared with HC and was correlated with serum IgG levels. Moreover, in vitro IgG production by CD19⁺ B cells was significantly increased in pSS and was positively and significantly correlated with serum IgG levels. FACS analysis revealed that the proportions of peripherally CD38^highIgD⁺ B cells and CD38^highIgD^- B cells were significantly increased in pSS. In addition, the proportion of CD38^highIgD⁺ B cells positively correlated with ESSDAI scores and serum levels of IgG, anti-Ro/SSA and anti-La/SSB antibodies while that of CD38^highIgD^- B cells showed no correlation with these parameters. Our data suggest that increased proportion of CD38^highIgD⁺ B cells in pSS is involved in IgG overproduction including autoantibodies, and correlates with disease progression.

Defective Early B Cell Tolerance Checkpoints in Sjögren's Syndrome Patients

OBJECTIVE

Central and peripheral B cell tolerance checkpoints are defective in many patients with autoimmune diseases, but the functionality of each discrete checkpoint has not been assessed in patients with Sjögren's syndrome (SS). We undertook this study to assess this functionality in SS patients.

METHODS

Using a polymerase chain reaction-based approach that allows us to clone and express, in vitro, recombinant antibodies produced by single B cells, we tested the reactivity of recombinant antibodies cloned from single CD19+CD21^low CD10+IgM^high CD27- newly emigrant/transitional B cells and CD19+CD21+CD10-IgM+CD27- mature naive B cells from 5 SS patients.

RESULTS

We found that the frequencies of newly emigrant/transitional B cells expressing polyreactive antibodies were significantly increased in SS patients compared to those in healthy donors, revealing defective central B cell tolerance in SS patients. Frequencies of mature naive B cells expressing autoreactive antibodies were also significantly increased in SS patients, thereby illustrating an impaired peripheral B cell tolerance checkpoint in these patients.

CONCLUSION

Defective counterselection of developing autoreactive B cells observed in SS patients is a feature common to many other autoimmune diseases and may favor the development of autoimmunity by allowing autoreactive B cells to present self antigens to T cells.

Kv1.3 Channel Blockade Modulates the Effector Function of B Cells in Granulomatosis with Polyangiitis

B cells are central to the pathogenesis of granulomatosis with polyangiitis (GPA), exhibiting both (auto)antibody-dependent and -independent properties. Class-switched memory B cells in particular are a major source of pathogenic autoantibodies. These cells are characterized by high expression levels of Kv1.3 potassium channels, which may offer therapeutic potential for Kv1.3 blockade. In this study, we investigated the effect of the highly potent Kv1.3 blocker ShK-186 on B cell properties in GPA in vitro. Circulating B cell subsets were determined from 33 GPA patients and 17 healthy controls (HCs). Peripheral blood mononuclear cells (PBMCs) from GPA patients, and HCs were stimulated in vitro in the presence and absence of ShK-186. The production of total and antineutrophil cytoplasmic antibodies targeting proteinase 3 (PR3-ANCA) IgG was analyzed by enzyme-linked immunosorbent assay and Phadia EliA, respectively. In addition, effects of ShK-186 on B cell proliferation and cytokine production were determined by flow cytometry. The frequency of circulating switched and unswitched memory B cells was decreased in GPA patients as compared to HC. ShK-186 suppressed the production of both total and PR3-ANCA IgG in stimulated PBMCs. A strong decrease in production of tumor necrosis factor alpha (TNFα), interleukin (IL)-2, and interferon gamma was observed upon ShK-186 treatment, while effects on IL-10 production were less pronounced. As such, ShK-186 modulated the TNFα/IL-10 ratio among B cells, resulting in a relative increase in the regulatory B cell pool. ShK-186 modulates the effector functions of B cells in vitro by decreasing autoantibody and pro-inflammatory cytokine production. Kv1.3 channel blockade may hold promise as a novel therapeutic strategy in GPA and other B cell-mediated autoimmune disorders.

Enhanced Bruton's Tyrosine Kinase Activity in Peripheral Blood B Lymphocytes From Patients With Autoimmune Disease

OBJECTIVE

Bruton's tyrosine kinase (BTK) transmits crucial survival signals from the B cell receptor (BCR) in B cells. Pharmacologic BTK inhibition effectively diminishes disease symptoms in mouse models of autoimmunity; conversely, transgenic BTK overexpression induces systemic autoimmunity in mice. We undertook this study to investigate BTK expression and activity in human B cells in the context of autoimmune disease.

METHODS

Using intracellular flow cytometry, we quantified BTK expression and phosphorylation in subsets of peripheral blood B cells from 30 patients with rheumatoid arthritis (RA), 26 patients with primary Sjögren's syndrome (SS), and matched healthy controls.

RESULTS

In circulating B cells, BTK protein expression levels correlated with BTK phosphorylation. BTK expression was up-regulated upon BCR stimulation in vitro and was significantly higher in CD27+ memory B cells than in CD27-IgD+ naive B cells. Importantly, BTK protein and phospho-BTK were significantly increased in B cells from anti-citrullinated protein antibody (ACPA)-positive RA patients but not in B cells from ACPA-negative RA patients. BTK was increased both in naive B cells and in memory B cells and correlated with frequencies of circulating CCR6+ Th17 cells. Likewise, BTK protein was increased in B cells from a major fraction of patients with primary SS and correlated with serum rheumatoid factor levels and parotid gland T cell infiltration. Interestingly, targeting T cell activation in patients with primary SS using the CTLA-4Ig fusion protein abatacept restored BTK protein expression in B cells to normal levels.

CONCLUSION

These data indicate that autoimmune disease in humans is characterized by enhanced BTK activity, which is linked not only to autoantibody formation but also to T cell activity.

Analysis of the cross-talk of Epstein-Barr virus-infected B cells with T cells in the marmoset

Despite the well-known association of Epstein–Barr virus (EBV), a lymphocryptovirus (LCV), with multiple sclerosis, a clear pathogenic role for disease progression has not been established. The translationally relevant experimental autoimmune encephalomyelitis (EAE) model in marmoset monkeys revealed that LCV-infected B cells have a central pathogenic role in the activation of T cells that drive EAE progression. We hypothesized that LCV-infected B cells induce T-cell functions relevant for EAE progression. In the current study, we examined the ex vivo cross-talk between lymph node mononuclear cells (MNCs) from EAE marmosets and (semi-) autologous EBV-infected B-lymphoblastoid cell lines (B-LCLs). Results presented here demonstrate that infection with EBV B95-8 has a strong impact on gene expression profile of marmoset B cells, particularly those involved with antigen processing and presentation or co-stimulation to T cells. At the cellular level, we observed that MNC co-culture with B-LCLs induced decrease of CCR7 expression on T cells from EAE responder marmosets, but not in EAE monkeys without clinically evident disease. B-LCL interaction with T cells also resulted in significant loss of CD27 expression and reduced expression of IL-23R and CCR6, which coincided with enhanced IL-17A production. These results highlight the profound impact that EBV-infected B-LCL cells can have on second and third co-stimulatory signals involved in (autoreactive) T-cell activation.

Biomarker Dynamics in B-cell Lymphoma: A Longitudinal Prospective Study of Plasma Samples Up to 25 Years before Diagnosis

The B-cell activation markers CXCL13, sCD23, sCD27, and sCD30 are associated with future lymphoma risk. However, a lack of information about the individual dynamics of marker-disease association hampers interpretation. In this study, we identified 170 individuals who had donated two prediagnostic blood samples before B-cell lymphoma diagnosis, along with 170 matched cancer-free controls from the Northern Sweden Health and Disease Study. Lymphoma risk associations were investigated by subtype and marker levels measured at baseline, at the time of the repeated sample, and with the rate of change in the marker level. Notably, we observed strong associations between CXCL13, sCD23, sCD27, and sCD30 and lymphoma risk in blood samples collected 15 to 25 years before diagnosis. B-cell activation marker levels increased among future lymphoma cases over time, while remaining stable among controls. Associations between slope and risk were strongest for indolent lymphoma subtypes. We noted a marked association of sCD23 with chronic lymphocytic leukemia (OR_Slope = 28, P_trend = 7.279 × 10^-10). Among aggressive lymphomas, the association between diffuse large B-cell lymphoma risk and slope was restricted to CXCL13. B-cell activation seemed to play a role in B-cell lymphoma development at early stages across different subtypes. Furthermore, B-cell activation presented differential trajectories in future lymphoma patients, mainly driven by indolent subtypes. Our results suggest a utility of these markers in predicting the presence of early occult disease and/or the screening and monitoring of indolent lymphoma in individual patients. Cancer Res; 77(6); 1408-15. ©2017 AACR.

Correlation of circulating CD27high plasma cells and disease activity in systemic lupus erythematosus

CD27 is a useful marker in assessing the number of circulating B cells and B cell subsets because it permits one step identification of the major B cell compartments, CD27- naïve and CD27+ memory B cells as well as CD27high plasma cells. Abnormalities in the distributionof CD27+ B cell subsets are useful in assessing disease activity in patients with systemic lupus erythematosus(SLE). In particular, the frequencyof CD27high plasma cells significantly correlates with lupus activity in both children and adults with SLE. Conventional immunosuppressive therapies affect the number of CD27- naive B cells and CD27high plasma cells, but do not target CD27+ memory B cells. These results suggest that disease flares may relate to the retention of CD27+ memory B cells after conventional immunosuppressive therapy and that new therapies that target these cells specifically may offer new opportunities to induce remission in SLE.

Interferon-β therapy specifically reduces pathogenic memory B cells in multiple sclerosis patients by inducing a FAS-mediated apoptosis

Growing evidences put B lymphocytes on a central stage in multiple sclerosis (MS) immunopathology. While investigating the effects of interferon-β (IFN-β) therapy, one of the most used first-line disease-modifying drugs for the treatment of relapsing-remitting MS, in circulating B-cell sub-populations, we found a specific and marked decrease of CD27⁺ memory B cells. Interestingly, memory B cells are considered a population with a great disease-driving relevance in MS and resulted to be also target of B-cell depleting therapies. In addition, Epstein-Barr virus (EBV), associated with MS etiopathogenesis, harbors in this cell type and an IFN-β-induced reduction of the memory B-cell compartment, in turn, resulted in a decreased expression of the EBV gene latent membrane protein 2A in treated patients. We found that in vivo IFN-β therapy specifically and highly induced apoptosis in memory B cells, in accordance with a strong increase of the apoptotic markers Annexin-V and active caspase-3, via a mechanism requiring the FAS-receptor/TACI (transmembrane activator and CAML interactor) signaling. Thus, efficacy of IFN-β therapy in MS may rely not only on its recognized anti-inflammatory activities but also on the specific depletion of memory B cells, considered to be a pathogenic cell subset, reducing their inflammatory impact in target organs.

The Significance of Ectopic Germinal Centers in the Minor Salivary Gland of Patients with Sjögren's Syndrome

We investigated the clinical and biological significance of germinal centers (GC) present in the minor salivary glands of patients with Sjögren's syndrome (SS). Minor salivary gland tissue biopsies from 93 patients with SS were used to identify GC-like structures, which were confirmed by CD21-positive follicular dendritic cell networks. Patients were compared based upon sociodemographics, glandular and extraglandular manifestations, and laboratory findings including autoantibody profiles, complement, and immunoglobulin levels; EULAR SS disease activity index (ESSDAI) and SS disease damage index (SSDDI) were also measured. GC-like structures were observed in 28 of 93 SS patients (30.1%). Mean focus scores and CRP levels were significantly higher in GC-positive patients than in GC-negative patients; GC-positive patients also exhibit a higher prevalence of rheumatoid factor and anti-SS-A/Ro antibodies compared to GC-negative patients. No differences in glandular or extra-glandular manifestations were evident between groups. In conclusion, SS patients with GC-like structures in the minor salivary glands exhibited laboratory profiles significantly different from those of their GC-negative counterparts. Long-term follow-up of these patients will be necessary to determine whether these laboratory abnormalities are predictive of clinical outcomes.

A comprehensive investigation on the distribution of circulating follicular T helper cells and B cell subsets in primary Sjögren's syndrome and systemic lupus erythematosus

Follicular T helper (Tfh) cells have a crucial role in regulating immune responses within secondary lymphoid follicles by directing B cell differentiation towards memory B cells and plasma cells. Because abnormal humoral responses are key features in both primary Sjögren's syndrome (pSS) and systemic lupus erythematosus (SLE), the aim of this study was to profile the pathological connection between peripheral Tfh cells and B cells in the two diseases. Twenty-five pSS patients, 25 SLE patients and 21 healthy controls were enrolled into the study. We determined the ratio of circulating Tfh-like cells, their interleukin (IL)-21 production and different B cell subsets by flow cytometry. We observed higher percentages of naive B cells in both diseases, while non-switched and switched memory B cells showed decreased frequencies. The proportions of double-negative B cells and plasmablasts were elevated in SLE and decreased in pSS. The percentages of transitional B cells and mature-naive B cells were higher in SLE. Patients with more severe disease course had an elevated ratio of TFH-like cells and increased IL-21 production. Moreover, expansion of Tfh-like cells correlated positively with parameters related to antibody secretion, including serum immunoglobulin (Ig)G, immune complexes (ICs) and autoantibodies. Correlation analysis between Tfh-like cells and certain B cell subsets revealed possible defects during B cell selection. In conclusion, our observations on the profound expansion of circulating Tfh-like cells and their IL-21 production, along with the characteristic aberrant peripheral B cell distribution in both pSS and SLE, indicate the prominent role of Tfh cell in the regulation of B cell selection.

Soluble levels of CD27 and CD30 are associated with risk of non-Hodgkin lymphoma in three Chinese prospective cohorts

Prospective studies conducted in Western populations have suggested that alterations in soluble CD27 (sCD27) and soluble CD30 (sCD30), two markers indicative of B-cell activation, are associated with risk of non-Hodgkin lymphoma (NHL). Given that the characteristics of NHL in East Asia differ from the West and mechanistic commonalities between these populations with respect to the role of intermediate endpoint biomarkers in lymphomagenesis have not been explored, we conducted a pooled nested case-control study from three prospective studies of Chinese men and women including 218 NHL cases and 218 individually matched controls. Compared with the lowest quartile, ORs (95% CIs) for the second, third and fourth quartiles of sCD27 were 1.60 (0.83-3.09), 1.94 (0.98-3.83) and 4.45 (2.25-8.81), respectively (p(trend) = 0.000005). The corresponding ORs for sCD30 were 1.74 (0.85-3.58), 1.86 (0.94-3.67) and 5.15 (2.62-10.12; p(trend) = 0.0000002). These associations remained statistically significant in individuals diagnosed with NHL 10 or more years after blood draw. Notably, the magnitude of the associations with NHL risk was very similar to those in Western populations in previous studies. These findings of the similar association between sCD27 or sCD30 and NHL risk across different populations support an important underlying mechanism of B-cell activation in lymphomagenesis.

Polychromatic flow cytometry in evaluating rheumatic disease patients

B cells are central players in multiple autoimmune rheumatic diseases as a result of the imbalance between pathogenic and protective B-cell functions, which are presumably mediated by distinct populations. Yet the functional role of different B-cell populations and the contribution of specific subsets to disease pathogenesis remain to be fully understood owing to a large extent to the use of pauci-color flow cytometry. Despite its limitations, this approach has been instrumental in providing a global picture of multiple B-cell abnormalities in multiple human rheumatic diseases, more prominently systemic lupus erythematosus, rheumatoid arthritis and Sjogren’s syndrome. Accordingly, these studies represent the focus of this review. In addition, we also discuss the added value of tapping into the potential of polychromatic flow cytometry to unravel a higher level of B-cell heterogeneity, provide a more nuanced view of B-cell abnormalities in disease and create the foundation for a precise understanding of functional division of labor among the different phenotypic subsets. State-of-the-art polychromatic flow cytometry and novel multidimensional analytical approaches hold tremendous promise for our understanding of disease pathogenesis, the generation of disease biomarkers, patient stratification and personalized therapeutic approaches.

Primary Sjögren's syndrome is characterized by distinct phenotypic and transcriptional profiles of IgD+ unswitched memory B cells

OBJECTIVE

The significance of distinct B cell abnormalities in primary Sjögren's syndrome (SS) remains to be established. We undertook this study to analyze the phenotype and messenger RNA (mRNA) transcript profiles of B cell subsets in patients with primary SS and to compare them with those in sicca syndrome patients and healthy controls.

METHODS

CD19+ B cells from 26 patients with primary SS, 27 sicca syndrome patients, and 22 healthy controls were analyzed by flow cytometry. Gene expression profiles of purified B cell subsets (from 3-5 subjects per group per test) were analyzed using Affymetrix gene arrays.

RESULTS

Patients with primary SS had lower frequencies of CD27+IgD- switched memory B cells and CD27+IgD+ unswitched memory B cells compared with healthy controls. Unswitched memory B cell frequencies were also lower in sicca syndrome patients and correlated inversely with serologic hyperactivity in both disease states. Further, unswitched memory B cells in primary SS had lower expression of CD1c and CD21. Gene expression analysis of CD27+ memory B cells separated patients with primary SS from healthy controls and identified a subgroup of sicca syndrome patients with a primary SS-like transcript profile. Moreover, unswitched memory B cell gene expression analysis identified 187 genes differentially expressed between patients with primary SS and healthy controls.

CONCLUSION

A decrease in unswitched memory B cells with serologic hyperactivity is characteristic of both established primary SS and a subgroup of sicca syndrome, which suggests the value of these B cells both as biomarkers of future disease progression and for understanding disease pathogenesis. Overall, the mRNA transcript analysis of unswitched memory B cells suggests that their activation in primary SS takes place through innate immune pathways in the context of attenuated antigen-mediated adaptive signaling. Thus, our findings provide important insight into the mechanisms and potential consequences of decreased unswitched memory B cells in primary SS.

Altered distribution of peripheral blood memory B cells in humans chronically infected with Trypanosoma cruzi

Numerous abnormalities of the peripheral blood T cell compartment have been reported in human chronic Trypanosoma cruzi infection and related to prolonged antigenic stimulation by persisting parasites. Herein, we measured circulating lymphocytes of various phenotypes based on the differential expression of CD19, CD4, CD27, CD10, IgD, IgM, IgG and CD138 in a total of 48 T. cruzi-infected individuals and 24 healthy controls. Infected individuals had decreased frequencies of CD19+CD27+ cells, which positively correlated with the frequencies of CD4+CD27+ cells. The contraction of CD19+CD27+ cells was comprised of IgG+IgD-, IgM+IgD- and isotype switched IgM-IgD- memory B cells, CD19+CD10+CD27+ B cell precursors and terminally differentiated CD19+CD27+CD138+ plasma cells. Conversely, infected individuals had increased proportions of CD19+IgG+CD27-IgD- memory and CD19+IgM+CD27-IgD+ transitional/naïve B cells. These observations prompted us to assess soluble CD27, a molecule generated by the cleavage of membrane-bound CD27 and used to monitor systemic immune activation. Elevated levels of serum soluble CD27 were observed in infected individuals with Chagas cardiomyopathy, indicating its potentiality as an immunological marker for disease progression in endemic areas. In conclusion, our results demonstrate that chronic T. cruzi infection alters the distribution of various peripheral blood B cell subsets, probably related to the CD4+ T cell deregulation process provoked by the parasite in humans.

The histopathology of labial salivary glands in primary Sjögren's syndrome: focusing on follicular helper T cells in the inflammatory infiltrates

Recently, we revealed the importance of follicular helper T cells (T(FH)) in the pathogenesis of primary Sjögren's syndrome (pSS). In the present study, we focused on the site of the inflammation and determined the composition of lymphocyte infiltration in labial salivary gland (LSG) biopsies with special emphasis on T(FH) and germinal center B cells. We selected tissue blocks obtained from ten patients at the time of disease onset. Detection of cell specific markers was performed with immunohistochemical and immunofluorescence stainings. We evaluated patients' clinical and laboratory features retrospectively and assessed the relation between disease course and early histopathological findings. LSG biopsies were graded based on the extension and arrangement level of periductal inflammatory cell infiltrates. T(FH) cell markers (CD84, PD-1, and Bcl-6) occurred predominantly in more organized structures with higher focus scores. The coexpression of CD3 and Bcl-6 markers clearly identified T(FH) cells close to Bcl-6(+) B cells with the typical formation of germinal centers. Systemic features were developed later in the disease course only in patients with highly structured infiltrates and the presence of T(FH) cells. Our observations suggest that the presence of T(FH) cells in LSGs at the disease onset may predict a more pronounced clinical course of pSS.

B-cell hyperactivity in primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is characterized by mononuclear inflammatory infiltrates and IgG plasma cells in salivary and lacrimal glands which lead to irreversible destruction of the glandular tissue and is accompanied by sensation of dryness of mouth and eyes. B cells play a central role in the immunopathogenesis and exhibit signs of hyperactivity. Hyperactivity of B cells is the consequence of the coordinated and integrated action of stimulation of the B-cell receptor, CD40 and toll-like receptors in the presence of appropriate cytokines. As discussed, overexpression of type I IFN and BAFF on one hand and IL-6 and IL-21 on the other hand are critically involved in the enhanced plasma cell formation in pSS patients. Hyperactivity of B cells results in secretion of autoantibodies and production of various cytokines. These insights in the role of B cells in the pathogenetic process of pSS offer ample targets for successful therapeutical intervention in pSS.

Ro52- and Ro60-specific B cell pattern in the salivary glands of patients with primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is characterized by the presence of autoantibodies against the ribonucleoprotein (RNP) particles Ro/SSA and La/SSB, and mononuclear cell infiltration of exocrine tissues, especially salivary and lachrymal glands. Low numbers of autoantigen-specific memory B cells and elevated levels of plasma cells have been detected previously in the peripheral blood (PB) of pSS patients compared to controls. As both Ro52 and Ro60-specific cells have been detected in the salivary glands (SG) of pSS patients, we aimed to characterize the SSA-specific B cell pattern in SG biopsies. A series of double immunohistochemical stainings were performed on paraffin-embedded tissue from 10 well-characterized pSS patients for each Ro52 and Ro60 along with CD19, CD5, CD20 or CD27, respectively. Ro52 and Ro60-specific cells detected in SG tissue were found to be CD19(+) B cells located outside the CD19(+)/CD20(+) B cell zones (BCZ) and also interstitially. These SSA-specific cells were also quantified. No SSA-specific cells were CD5(+), indicating that they do not belong to the B-1 B cell subset. Furthermore, no SSA-specific cells were observed within the CD20(+) BCZ. Hence, no SSA-specific memory B cells were detected in these individuals. Contrary to this, SSA-specific cells were found to be CD19(+)/CD27(++), demonstrating that they are differentiating short or long-lived plasma cells. Taken together, our findings suggest that these lower levels of SSA-specific memory B cells in PB and absence of SSA-specific memory B cells in SG of pSS patients could result from activation of these cells into plasma cells at the site of inflammation.

Follicular helper T cells may play an important role in the severity of primary Sjögren's syndrome

The aim of this study was to investigate the possible role of follicular helper T (TFH) cells in the pathogenesis of primary Sjögren's syndrome (pSS) by analyzing immune-competent cells and serological markers with special emphasis on clinical symptoms. We enrolled 50 pSS patients and 16 healthy individuals in the study. Patients had elevated ratio of peripheral TFH cells, however, when dividing patients into two groups defined by the presence of extraglandular manifestations (EGMs), only patients with EGMs differed from controls significantly. Moreover, TFH cell percentages correlated positively with both activated T cell and Tr1 cell values. On the contrary, TFH cell percentages showed negative correlation with both IgM and IgG memory B cell proportions. Elevated TFH percent\ages were observed in the anti-SSA/SSB positive patients, and also in patients with higher IL-12, IL-21 levels and focus score values. Increased TFH cell proportions seem to have an important role in disease development.

Expression of CD70 in nasal natural killer/T cell lymphoma cell lines and patients; its role for cell proliferation through binding to soluble CD27

Nasal natural killer (NK)/T cell lymphoma (NNKTL) is associated with Epstein-Barr virus (EBV). The present study analysed gene expression patterns of the NNKTL cell lines SNK6, SNK1 and SNT8, which are positive for EBV and latent membrane protein (LMP)-1, using a complementary DNA array analysis. We found that CD70 was specifically expressed in SNK6 and SNT8. Reverse transcription polymerase chain reaction and flow cytometric analyses confirmed that CD70 was expressed in all 3 NNKTL cell lines, but not in the other EBV-positive NK-cell lines. In vitro studies showed that NNKTL cell lines proliferated, in a dose-dependent fashion, in response to exogenous soluble CD27, which is the ligand for CD70. In NNKTL patients, we confirmed that the CD70 was expressed on the lymphoma cells in NNKTL tissues and that soluble CD27 was present in sera at higher levels as compared to healthy individuals. Finally, complement-dependent cytotoxicity assay showed that anti-CD70 antibody mediated effective complement-dependent killing of NNKTL cells and the affected target CD70 expression on the cells. These results suggest that CD70 acts as a functional receptor binding to soluble CD27, resulting in lymphoma progression and that immunotherapy using anti-CD70 antibody may be a potential candidate for treatment for NNKTL.

Low number of memory B cells in the salivary glands of patients with primary Sjögren's syndrome

We have previously shown that patients with primary Sjögren's Syndrome (pSS) show a significant reduction of autoantigen specific CD27(+) memory B cells and an abnormally elevated level of autoantibody producing plasma cells in peripheral blood (PB) compared to controls. Because both memory B cells and plasma cells have been detected in salivary glands (SG) of pSS patients, we aimed to study the B cell pattern in SG biopsies. Double immunohistochemical staining of CD20 and CD27 was carried out on paraffin-embedded SG tissue from 10 pSS patients to distinguish CD20(+)/CD27(+) memory B cells, and identify the CD20(+) glandular B cell zones (BCZ). Given that plasma blasts and plasma cells are CD27(++) and CD20(- ), additional CD138 single staining of serial sections allowed the distinction of CD27(++)/CD138(- ) plasma blasts located within the BCZ from CD27(++)/CD138(+) plasma cells that were found mostly on the periphery of the BCZ and also observed interstitially. Both BCZ and the memory B cell populations were then quantified. Contrary to what has been reported earlier through immunoflourescent staining of memory B cells in SG tissue, we have shown that there is a low number of memory B cells located within the glandular BCZ. Plasma blasts and plasma cells, however, were more abundant in the SG. Together our findings suggest that these low numbers of memory B cells in both PB and SG of pSS patients may be the result of activation of these cells into plasma cells at the site of inflammation.

[Impaired expression of Act1mRNA in B cells of patients with Sjögren's syndrome]

Sjögren's syndrome (SS) is a systemic autoimmune disorder characterized by profound lymphocytic infiltration into the lacrimal and salivary glands, thereby diminished secretory function. B cell hyper-activation is a predominant feature of SS related to hypergammaglobulinemia and production of autoantibodies. The adaptor molecule NF-kB activator 1 (Act1) plays an important role in the homeostasis of B cells by attenuating CD40 and B cell-activating factor belonging to the tumor necrosis factor family receptor (BAFFR) signaling. Act1-deficient mice develop autoimmune manifestations similar to SS, which are hypergammaglobulinemia, high levels of anti-SSA and anti-SSB autoantibodies. In this study, to investigate the role of Act1 in the pathogenesis of SS, we examined Act1mRNA expressions in B cells from patients with SS and discussed the association of Act1 with parameters and clinical manifestations of SS. We showed the low level of Act1mRNA expression in patients with SS and reciprocal association of Act1 with serum IgG level. Diminished Act1mRNA expression in SS may be associated with B cell hyperactivity and elevated immunoglobulin production in SS by uncontrolled B cell activation signal through CD40 and BAFFR.

Soluble CD27 induces IgG production through activation of antigen-primed B cells

OBJECTIVES

High levels of soluble CD27 (sCD27), a marker of immune activation, are found in several infectious [including human immunodeficiency virus type-I (HIV-1)] and autoimmune diseases; however, a direct biological effect of sCD27 on B cells has not been established. The aim of this study was to investigate whether sCD27, by binding to CD70, can induce immunoglobulin G (IgG) production from B cells.

METHODS

B cells from healthy and HIV-1-infected individuals were cultured with recombinant human sCD27 (rhsCD27), and IgG production was measured. The role of rhsCD27 in inducing the expression of transcription factors involved in plasma cell differentiation was evaluated. Furthermore, we investigated the impact of different cytokines on the modulation of CD70 expression on B cells and the relationship between levels of IgG and sCD27 in serum from healthy and HIV-1-infected individuals.

RESULTS

We demonstrated that rhsCD27 induced IgG production from antigen-primed (CD27+) B cells. This effect was mediated by rhsCD27 binding to CD70 on B cells leading to activation of Blimp-1 and XBP-1, transcription factors associated with plasma cell differentiation. We found a significant correlation between levels of serum sCD27 and IgG in HIV-1-infected individuals and healthy controls.

CONCLUSIONS

sCD27 may act to enhance immunoglobulin production and differentiation of activated memory or recently antigen-experienced B cells, thus providing an activation signal to antigen-experienced B cells. This mechanism may operate during autoimmune and chronic infectious diseases, situations in which continuous immune activation leads to upregulation of CD70 expression and increased sCD27 cleavage.

Immune regulation and B-cell depletion therapy in patients with primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is an autoimmune exocrinopathy characterized by chronic inflammation and destruction of the salivary and lacrimal glands. B- and T- lymphocyte infiltrations in the salivary glands with development of germinal center-like structures are characteristic for pSS. Overexpression of soluble factors, such as interferon α (IFNα) and B-cell activating factor (BAFF), are supposed to be important factors in the initiation and continuation of this disorder. The efficacy and success of B-cell depleting therapy in reducing disease activity in pSS patients for about six to nine months supports the notion that B-cells are major key players in disease manifestation of pSS. In addition to B-cells, also Th-cells (mainly Th17) seem to be involved in the pathogenetic process. In this review, we will discuss recent research findings regarding the cytokines IFNα and BAFF as wells as the role of B- and T-cells in pSS. Emphasis will be put on the impact of B-cell depletion therapy as well as on the presumed impact of therapies aimed for targeting BAFF, either as a sole modality or as a combined treatment with B-cell depletion.

Autoantigen-specific memory B cells in primary Sjögren's syndrome

Sjögren's syndrome (SS) is a systemic rheumatic autoimmune disease affecting the exocrine glandular function and is characterized by the presence of autoantibodies against the ribonucleoprotein particles, SS-A/Ro and SS-B/La, and mononuclear cell infiltration of exocrine tissues. Our aim is to characterize memory B cell pattern and function in relation to the progression of the disease, by analysing samples from a well-defined cohort of patients with primary SS. We have measured the number of Ro/La-specific plasma cells in peripheral blood mononuclear cells (PBMC) from 23 patients and 20 healthy controls by direct enzyme-linked immunospot (ELISPOT) assay. Furthermore, we quantified the Ro- and La-specific memory B cells in these individuals by a 6-day in vitro polyclonal stimulation of PBMC followed by an antigen-specific ELISPOT assay for the detection of memory B cells. In addition to this, ELISA profiling of autoantibodies was carried out using patients' plasma and supernatant, collected post-mitogen stimulation of PBMC. The average Ro60-, Ro52- and La48-specific plasma cells in PB was 9, 17 and 13 cells in 10(5) PBMC, respectively. After in vitro stimulation, these numbers increased to 43, 50 and 26 for Ro60, Ro52 and La48, correspondingly. However, the fraction of memory B cells activated into antibody-secreting cells was lower than the overall IgG B cell population. We conclude that these lower Ro/La-specific memory B cell levels may indicate that a greater portion of the Ro- and La-specific B cells are in an activated stage. This is in tune with previous reports.

Lymphoid organisation in labial salivary gland biopsies is a possible predictor for the development of malignant lymphoma in primary Sjögren's syndrome

Objective

The 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.

Methods

Labial 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.

Results

At 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).

Conclusions

The 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.

Aberrant expression of CD6 on B-cell subsets from patients with Sjögren's syndrome

CD6 is one of a pair of related genes encoding CD5-associated receptors on all T cells and a subset of B cells. The current availability of "T1h", a humanized anti-CD6 monoclonal antibody for B cell-mediated autoimmune disorders revives analysis of the B-cell subset expression of CD6, particularly in primary Sjögren's syndrome (SS). Refined phenotype of B-lymphocytes peripheral blood (PB), bone marrow and tonsils revealed that the overlap between the expression of CD6 is less close to that of CD5 than currently acknowledged. In contrast to CD5, CD6 is absent on transitional B cells, while present on mature and memory B cells. Interestingly, the PB proportion of CD6(+) B cells is decreased in patients with primary SS, as opposed to those with rheumatoid arthritis. The reduction in primary SS does not result from the shedding of CD6 from the membrane of B cells, but from the lowering of memory B lymphocytes. It may result from the ability of CD6 to make transmigration of CD27(+) memory B cells into the salivary glands (SGs) easier. Consistent with this view is our finding that CD166 (one of the ligands for CD6) is highly expressed on epithelial cells of patients' SGs. This study is relevant in that the humanized T1h anti-CD6 becomes an alternative to anti-CD20 for treatment of primary SS.

Alterations on peripheral blood B-cell subpopulations in very early arthritis patients

OBJECTIVE

To characterize circulating B-cell subpopulations of arthritis patients with <6 weeks of disease duration.

METHODS

Peripheral blood samples were collected from very early untreated polyarthritis patients, with <6 weeks of disease duration, for flow cytometric evaluation of B-cell subpopulations. Samples from patients who were later diagnosed as RA [very early RA (VERA)] were also collected 4-6 weeks after starting a low dose of prednisone (5-10 mg) and 4 months after reaching the minimum effective dose of MTX. A matched healthy group was used as a control.

RESULTS

VERA patients have a lower percentage of total peripheral blood memory B cells (CD19(+)CD27(+)) and a significant decrease in the frequency of circulating pre-switch memory B cells (CD19(+)IgD(+)CD27(+)) as compared with controls. Therapy with corticosteroids or MTX was unable to restore the normal frequencies of these B-cell subpopulations. A significant decrease in peripheral pre-switch memory B cells is equally observed in other early arthritis patients. Furthermore, no significant differences are found in the frequencies of CD4(+) and CD8(+) T cells in all patient groups.

CONCLUSIONS

In very early polyarthritis patients, there is a reduction in circulating pre-switch memory B cells. The reasons that may account for this effect are still unknown. Short-term corticosteroids and MTX do not seem to have a direct effect on circulating B-cell subpopulations in VERA patients.

B cells in Sjögren's syndrome: indications for disturbed selection and differentiation in ectopic lymphoid tissue

Primary Sjögren's syndrome (pSS) is an autoimmune disorder characterized by specific pathological features. A hallmark of pSS is B-cell hyperactivity as manifested by the production of autoantibodies, hypergammaglobulinemia, formation of ectopic lymphoid structures within the inflamed tissues, and enhanced risk of B-cell lymphoma. Changes in the distribution of peripheral B-cell subsets and differences in post-recombination processes of immunoglobulin variable region (IgV) gene usage are also characteristic features of pSS. Comparison of B cells from the peripheral blood and salivary glands of patients with pSS with regard to their expression of the chemokine receptors CXCR4 and CXCR5, and their migratory capacity towards the corresponding ligands, CXCL12 and CXCL13, provide a mechanism for the prominent accumulation of CXCR4⁺CXCR5⁺ memory B cells in the inflamed glands. Glandular B cells expressing distinct features of IgV light and heavy chain rearrangements, (re)circulating B cells with increased mutations of cμ transcripts in both CD27^- and CD27⁺ memory B-cell subsets, and enhanced frequencies of individual peripheral B cells containing IgV heavy chain transcripts of multiple isotypes indicate disordered selection and incomplete differentiation processes of B cells in the inflamed tissues in pSS. This may possibly be related to a lack of appropriate censoring mechanisms or different B-cell activation pathways within the ectopic lymphoid structures of the inflamed tissues. These findings add to our understanding of the pathogenesis of this autoimmune inflammatory disorder and may result in new therapeutic approaches.