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.

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.

Peritumoral dermis of squamous cell carcinomas in renal transplant recipients contains less CD11c+ myeloid dendritic cells and FoxP3+ T cells compared to immunocompetent controls

BACKGROUND

Renal transplant recipients (RTR) have an increased risk of developing cutaneous squamous cell carcinomas (SCC). These SCC are often more aggressive than SCC in immunocompetent individuals.

OBJECTIVES

In this comparative study, we analysed the cell composition in the tissue immediately surrounding invasive SCC in immunosuppressed RTR and immunocompetent controls in an effort to further elucidate the role of the local immune system.

METHODS

Morphology and quantity of various dendritic cell (DC) subsets, macrophages and FoxP3+ T cells were analysed by immunohistochemical staining.

RESULTS

The number of CD11c+ myeloid DC and FoxP3+ T cells was significantly reduced in RTR, whereas the number of plasmacytoid DC, Langerhans cells and macrophages was similar in RTR and controls.

CONCLUSIONS

A reduction in CD11c+ mDC in peritumoral dermis in RTR might contribute to impaired immunosurveillance thus giving rise to an increased risk to develop aggressive SCC in these patients.

Ductal epithelial expression of Ro52 correlates with inflammation in salivary glands of patients with primary Sjögren's syndrome

Ro52 is an E3 ubiquitin ligase with a prominent regulatory role in inflammation. The protein is a common target of circulating autoantibodies in rheumatic autoimmune diseases, particularly Sjögren's syndrome (SS). In this study we aimed to investigate the expression of the SS target autoantigen Ro52 in salivary glands of patients with primary Sjögren's syndrome (pSS). Ro52 expression was assessed by immunohistochemical staining of paraffin-embedded and frozen salivary gland biopsies from 28 pSS patients and 19 non-pSS controls from Swedish and Norwegian registries, using anti-human Ro52 monoclonal antibodies. The degree and pattern of staining and inflammation was then evaluated. Furthermore, secreted Ro52 protein was measured in saliva and serum samples from the same individuals through a catch-enzyme-linked immunosorbent assay (ELISA). Ro52 was highly expressed in all the focal infiltrates in pSS patients. Interestingly, a significantly higher degree of Ro52 expression in ductal epithelium was observed in the patients compared to the non-pSS controls (P < 0·03). Moreover, the degree of ductal epithelial expression of Ro52 correlated with the level of inflammation (Spearman's r = 0·48, P < 0·0120). However, no secreted Ro52 protein could be detected in serum and saliva samples of these subjects. Ro52 expression in ductal epithelium coincides with degree of inflammation and is up-regulated in pSS patients. High expression of Ro52 might result in the breakage of tolerance and generation of Ro52 autoantibodies in genetically susceptible individuals. We conclude that the up-regulation of Ro52 in ductal epithelium might be a triggering factor for disease progression in SS.

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.

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.

Phenotypic diversity of peripheral blood plasma cells in primary Sjögren's syndrome

Production of autoantibodies is one of the main features of primary Sjögren's syndrome (pSS). Long-lived plasma cells (PC) can produce autoantibodies for prolonged period of times without being affected by immunosuppressive therapies. As of today, little is known about the long-lived PC subset and their contribution to autoimmunity. We have characterized the phenotypic and migratory properties of peripheral blood PC isolated from pSS patients (grouped by focus score, FS) and compared them to PC from rheumatoid arthritis (RA) patients and normal non-autoimmune subjects. We observed two populations of PC in all study groups, CD19+ PC and CD19- PC. Interestingly, the CD19- PC subset was most prominent in autoimmune patients (pSS and RA) compared to normal controls. Further investigation of the PC phenotype revealed that a high percentage of both CD19+ and CD19- PC isolated from pSS and RA patients did not express the CD27 marker, which is normally highly expressed on all types of PC. Differences in the expression of markers such as IgM, IgG, CD95 and CXCR3 in the group with high FS compared to FS = 1, underscore the heterogeneity of pSS patient group and demonstrate that phenotypic pattern of circulating PC associates with the severity of inflammation in the salivary glands of these patients. Our migration experiments show that addition of CXCL12 to PC in vitro, do not alter the migration potential of PC in any group tested. However, we observed an overall higher spontaneous migration of PC from pSS compared to both RA and normal controls.

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

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.

Elevated Serum Levels of Soluble E-Cadherin in Patients with Primary Sjogren's Syndrome

The aim of this study was to investigate serum levels of soluble E-cadherin (sE-cadherin) in relation to lymphocytic organization and to characterize the expression of E-cadherin and integrin alphaEbeta7/CD103 in salivary gland epithelium of patients with Sjögren's syndrome (SS). Serum levels of sE-cadherin were significantly increased in SS compared to non-SS and nonsignificantly in germinal centre (GC)+ compared to GC- patients. Membrane-bound E-cadherin was detected on the majority of acinar and ductal epithelial cells in both SS and non-SS. alphaEbeta7/CD103-positive cells were found scattered in focal infiltrates and GC, and in small clusters close to ductal and acinar epithelium at an increased level in SS compared to non-SS. Interestingly, E-cadherin-positive cells were detected randomly dispersed in focal lymphocytic infiltrates in 10/21 patients. By double-labelling, the cells with the E-cadherin-positive component were identified as CD68(+) macrophages. Elevated serum levels of sE-cadherin indicate an increased epithelial cell turnover and shedding, and sE-cadherin deserves further analysis as a potential diagnostic tool for SS.

Influence on Spontaneous Tissue Inflammation by the Major Histocompatibility Complex Region in the Nonobese Diabetic Mouse

We investigated the role of the major histocompatibility complex (MHC) region in the specificity of autoimmunity by analysing specifically the development of sialadenitis, but also insulitis, nephritis and autoantibody production in autoimmune-prone nonobese diabetic (NOD) mice where the MHC H2g7 haplotype had been exchanged for the H2q (NOD.Q) or H2p (NOD.P) haplotype. The exchange of H2 haplotype did not affect the frequency of sialadenitis because the H2q and H2p congenic NOD strains developed sialadenitis with the same incidence as NOD. However, the severity of sialadenitis varied among the strains, as NOD.Q >NOD >NOD.P. At 11-13 weeks of age, the NOD.Q (H2q) female mice developed more severe sialadenitis compared to NOD.P (H2p) (P=0.038). At 20 weeks, the NOD (H2g7) female mice showed more severe sialadenitis than NOD.P (P=0.049). This is in contrast to the development of insulitis in the present strains, because the incidence of insulitis was almost completely inhibited by the replacement of the H2g7 haplotype of NOD. The incidence of insulitis in NOD.Q was 11-22%, compared to 75% in NOD, which correlated well with lower titres of anti-glutamic acid decarboxylase (anti-GAD) antibodies in NOD.Q compared to NOD (P=0.009). However, the introduction of the H2q haplotype into the NOD strain instead directed the autoimmune response towards the production of lupus types of autoantibodies, because the incidence of antinuclear antibodies (ANA) in NOD.Q was 89% compared with 11% in NOD.P and 12% in NOD mice, which in turn correlated with a high incidence of nephritis in NOD.Q compared to NOD. Consequently, we show that different haplotypes of MHC are instrumental in directing the specificity of the spontaneous autoimmune inflammation.

T cell proliferation and apoptosis in HIV-1-infected lymphoid tissue: impact of highly active antiretroviral therapy

T cell turnover was studied in situ in tonsillar lymphoid tissue (LT) from HIV-1-infected individuals during 48 weeks of highly active antiretroviral therapy (HAART) and compared to that of HIV-1-negative controls. Prior to therapy, CD4 cell proliferation (%CD4+ Ki67+) and apoptosis (%CD4+ TUNEL+) were increased in HIV-1-infected LT and both parameters correlated with tonsillar viral load. CD8 cell proliferation (%CD8+ Ki67+) was increased 4- to 10-fold, mainly in the germinal centers. Apoptotic CD8+ T cell levels (%CD8+ TUNEL+) were raised preferentially in the tonsillar T cell zone. The frequency of CD8+ Ki67+ and CD8+ TUNEL+ T cells correlated with tonsillar viral load and with the fraction of CD8(+) T cells expressing activation markers. During HAART, CD4 cell turnover normalized while CD8 cell turnover was dramatically reduced. However, low level viral replication concomitant with slightly elevated levels of CD8 cell turnover indicated a persistent cellular immune response in LT. In conclusion, enhanced T cell turnover may reflect effector cells related to HIV-1 infection.

Fas-induced apoptosis is a rare event in Sjögren's syndrome

The aim of this study was to perform a controlled in situ analysis on the incidence of apoptosis, investigate the expression of apoptosis-mediating proteins, and determine the frequency of apoptotic CD4+ and CD8+ T cells in Sjögren's syndrome (SS). The study was extended to patients with atrophy-fibrosis (AF) not related to SS, as well as to a control group. Immunohistochemistry and the terminal deoxynucleotidyl transferase mediated dUTP digoxigenin nick end labeling (TUNEL) method were applied to study the Fas and FasL expression and the incidence of apoptosis in salivary glands (SG) from patients with primary and secondary SS, AF, and controls. These methods were also combined to enable simultaneous detection of apoptotic and CD4+ or CD8+ T cells. Despite abundant expression of Fas and FasL in SS SG, apoptotic cells were not exceeding 1% in the foci of infiltrating mononuclear cells (IMC). Double staining showed that the frequency of apoptosis was low among both CD4+ and CD8+ T cells. Only a few TUNEL+ epithelial cells were found in all patient groups. Fas was expressed predominantly on SS IMC, single SS epithelial cells, and a few normal acinar cells, but not in AF SG. Although FasL was present on SS and AF IMC and epithelial cells, it was rarely detected in normal tissue. Consequently we demonstrate that Fas-induced apoptosis among SS SG is a rare event. Our findings support an earlier hypothesis indicating that IMC seem to be able to escape apoptosis, resulting in foci of inflammatory cells. Notably, however, no obvious correlation can be drawn to previous studies where a high incidence of apoptosis of epithelial cells was proposed as an important mechanism leading to decreased glandular function, which is a hallmark of SS.

[Heredity and immunology in Sjogren's syndrome]

BACKGROUND

Over the next 3-5 years, the rapid progress in genomic research will enable the discovery of many genes associated with the more common diseases. An example of such a common disease is the rheumatic disorder Sjögren's syndrome, an autoimmune disease. A more precise genetic explanation of the mechanism leading to Sjögren's syndrome remains to be given.

MATERIAL AND METHODS

One way of investigating the disease related genes in such complex polygenic diseases is to perform linkage studies in families with two or more affected. Another possibility is to conduct association studies on trios (parents and affected child), case control studies, or other experimental designs. In association studies one is testing if an allele is significantly elevated among patients compared to controls, while in linkage analyses one finds subchromosomal regions that are significantly more often inherited by patients than by healthy family members.

RESULTS

The most well defined genetic association in Sjögren's syndrome is currently related to different HLA alleles and their association with anti-Ro/SSA and anti-La/SSB autoantibodies. Additional genetic studies focusing on non-HLA regions are under way.

INTERPRETATION

Increased genetic knowledge would allow optimisation of the diagnostic criteria as well as development of new and more effective treatment for Sjögren's syndrome, which causes substantial suffering for a large group of patients.

Lymphoid cell accumulation in salivary glands of autoimmune MRL mice can be due to impaired apoptosis

MRL-lpr mice and the congenic strain MRL +/+ exhibit pathological abnormalities in the salivary glands similar to Sjögren's syndrome in humans. The lpr genotype has been identified as a mutation in the gene encoding Fas which is a cell surface protein that mediates apoptosis. The mutation is leaky, allowing for low levels of the APO-1/Fas (CD95) receptor and partial activity of Fas/Fas ligand-mediated programmed cell death in this strain. To examine the expression of Fas in situ, the authors analysed thymus, lymph node and salivary gland tissue from BALB/c, MRL +/+ and MRL-lpr mice by an immunohistochemical technique (ABC-immunoperoxidase) using an anti-Fas (Jo2) antibody. For detection of apoptotic cells the authors used the terminal deoxynucleotidyl-transferase-mediated dUTP-digoxigenin nick end labelling (TUNEL) method. Thymus from MRL +/+ and normal BALB/c mice showed a higher frequency of Fas expression than was seen in the lpr mice, but the +/+ mice had similar expression of Fas in lymph nodes as lpr mice. The Fas protein was detected among infiltrating mononuclear cells in the salivary glands of both lpr and +/+ mice. Apoptotic cells were found in the thymus with similar frequency in all three strains, while in the lymph nodes only BALB/c mice showed apoptosis. There was no, or very low, frequency of apoptosis among infiltrating mononuclear cells in salivary glands of both MRL strains. In conclusion, despite mutation of the Fas gene in the MRL-lpr strain, there was nevertheless an expression of the apoptosis-related Fas protein in lymphoid tissue and salivary glands of these mice. Based on analysis of apoptotic activity, the impaired Fas in autoimmune MRL mice seems to affect primarily the peripheral organs.

Effects of sialadenitis after cellular transfer in autoimmune MRL/lpr mice

The MRL/Mp mice bearing a lymphoproliferative gene, lpr (MRL/Mp-lpr/lpr), provide an appropriate model for the study of autoimmune mechanisms leading to the destruction of salivary and lacrimal gland tissue in Sjögren's syndrome. By 7-8 weeks of age, progressive focal inflammatory cell infiltrates are observed in salivary glands. We examined the possibility of transferring this disorder into syngeneic, young animals. Spleen cells and infiltrating mononuclear cells (MNC) enzymatically eluted from salivary glands were used. The results showed that sialadenitis could be transferred in vivo to young MRL/lpr mice by splenic and salivary gland MNC. The most striking finding was observed in male recipients where the highest incidence of sialadenitis (5/5) was seen in the group injected intravenously with a small dose (1 x 10(6) of salivary gland MNC, CD8+ splenic cells alone were not able to transfer disease. On the other hand, CD4+ splenic cells induced a more severe sialadenitis compared to the control animals. The transfer of pooled cells from salivary glands resulted in the most severe and accelerating sialadenitis (P < 0.05) in female recipients compared with the control animals. Overall, the highest sialadenitis scores (> 0.10) were obtained only after transfer of CD4+ spleen cells and infiltrating salivary gland MNC. These findings indicate that sialadenitis in MRL/lpr mice is mediated by cellular mechanisms and suggest that the infiltrating MNC have the ability to accelerate autoimmune disease in the salivary glands.

Short-term administration of selected anti-T-cell receptor V beta chain specific MoAb reduces sialadenitis in MRL/lpr mice

Sialadenitis develops spontaneously in MRL/Mp mice bearing a lymphoproliferative gene, lpr (MRL/Mp-lpr/lpr). Based on recent observations of an oligoclonal expansion of T-cell receptor (TCR) expressing V beta chain families (V beta 4, V beta 8.1,2, V beta 10b) in salivary glands of these mice we have initiated selective antibody therapy. Treatment with monoclonal antibodies (MoAb) specific for T cells expressing a mixture of TCR V beta 4, V beta 8.1,2 and V beta 10b was applied to MRL/lpr mice before and after the spontaneous development of sialadenitis. The in vivo treatment with V beta 4, V beta 8.1,2 and V beta 10b MoAb did not prevent the development of sialadenitis. However, in animals with established sialadenitis, treatment with the MoAb significantly decreased the inflammation compared with the control groups. Immunohistochemical staining of cell phenotypes demonstrated a change in the ratio of CD4/CD8 in the animals with established sialadenitis. Altogether, these findings illustrate that it is possible to modulate sialadenitis and infiltrate cell phenotypes in vivo in MRL/lpr mice with specific anti-TCR V beta MoAb treatment.

Characterization of T cell receptor repertoire and anti-Ro/SSA autoantibodies in relation to sialadenitis of NOD mice

Non-obese diabetic (NOD) mice develop sialadenitis which morphologically resembles the exocrinopathy in human Sjögren's syndrome (SS). The sialadenitis is characterized by focal infiltrates of inflammatory cells. Immunoenzyme staining (ABC-technique) and monoclonal antibodies defining CD4, CD8, CD11b, TCR alpha/beta, gamma/delta, V beta 2, V beta 4, V beta 6, V beta 7, V beta 8.1, 2, V beta 10b and V beta 11 were used to examine the infiltrating mononuclear cells (MNC) in salivary glands of NOD mice. TCR alpha beta + cells dominated clearly over TCR gamma delta + cells in the salivary glands. A predominance of CD4+ T-cells was identified, while a small population of CD8+ cells was found in the salivary gland infiltrates. CD11b+ mononuclear cells were sporadically seen within the salivary gland lesions. All different TCR V beta:s which were analysed appeared to be utilized at the site of MNC infiltration in salivary glands; although with various frequencies. The frequency pattern of V beta gene expression in salivary glands was V beta 8.1,2 (15%) > V beta 6 (12%) > V beta 4 (11%) > V beta 10b (5%) > V beta 11 (5%) = V beta 2 (5%) > V beta 7 (3%). Analysis of the TCR V beta utilization in corresponding lymph nodes revealed a quite similar frequency pattern as found in the salivary glands. Serum samples were also tested for anti-Ro52, Ro60 and anti-La antibodies with Western blot. Autoantibody production was limited to anti-Ro/SSA and 3/37 (8%) of the mice were found to produce anti-Ro52 kD antibodies. The degree of sialadenitis (focus score) appeared not to influence reactivity to the Ro52 kD protein.

MRL/lpr mice produce anti-Ro 52,000 MW antibodies: detection, analysis of specificity and site of production

MRL/lpr mice are studied as one of the animal models of the human autoimmune disease Sjögren's syndrome. The mice develop inflammatory exocrinopathy resembling that of patients with Sjögren's syndrome. To investigate if MRL/lpr mice produce the anti-Ro/SS-A and anti-La/SS-B autoantibodies common to Sjögren's syndrome patients, mouse sera were tested in ELISA and Western blot with recombinant Ro 60,000 MW, Ro 52,000 MW and La antigen. Thirty per cent of mice aged 4 months and 5% of mice aged 2 months produced antibodies to human Ro 52,000 MW. Antibodies to Ro 60,000 MW and La were found in a low percentage of the older mice but not at all in the younger mice. Immunohistological staining of mouse organ sections demonstrated anti-Ro 52,000 MW-producing cells in spleen, lymph nodes and salivary glands of seropositive animals. These findings provide further evidence for the usefulness of the MRL/lpr mouse as a model for Sjögren's syndrome.

Oligoclonality of T cells in salivary glands of autoimmune MRL/lpr mice

The aim of this study was to obtain further information about exocrine glandular immunopathology and the potential of the MRL/lpr strain as a model of Sjögren's syndrome. Immunoenzyme staining (ABC technique) and monoclonal antibodies defining CD3 T-cell receptor (TcR) alpha beta, gamma delta and TcR V beta 2, V beta 4, V beta 6, V beta 7, V beta 8.1,2, V beta 10b and V beta 11 were used to identify the mononuclear cells (MNC) in salivary gland infiltrates and lymph nodes of 2- and 4-5-month-old female MRL/lpr mice. TcR alpha beta + cells dominated clearly over TcR gamma delta + cells in both salivary glands and lymph nodes. In addition, to be expressed on lymphocyte-like cells, TcR gamma delta + cells also had a dendritic appearance. The frequency pattern of TcR expression in early inflammation (2 months) was V beta 8.1, 2 > V beta 6 > V beta 4 > V beta 10b > V beta 2 > V beta 7 > V beta 11. Clear differences in frequencies could be found between salivary glands and lymph nodes in established sialadenitis (4-5 months). Particularly V beta 4, V beta 8.1,2 and V beta 10b showed expansion in salivary glands at > or = 4 months. In conclusion, this study shows a diverse repertoire of TcR at local sites of MNC infiltration in autoimmune MRL/lpr mice. However, with increasing age it also shows a preferential utilization of certain V beta gene products.