Cardamonin inhibits pro-inflammatory cytokine production and suppresses NO pathway in PBMCs from patients with primary Sjögren's syndrome.

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disorder with a complex pathophysiology primarily affecting exocrine glands, leading to compromised secretory function. Recent studies imply that many inflammatory mediators, such as pro-inflammatory cytokines and nitric oxide, are critical in the development and perpetuation of pSS systemic manifestations. In the current study, we aimed to investigate the ex vivo immunomodulatory effect of cardamonin (C16H14O4), on pro-inflammatory cytokines, TNF-α, IL-6 and inducible nitric oxide synthase (iNOS) expression during pSS. For this purpose, peripheral blood mononuclear cells isolated from pSS patients and healthy controls were cultured with different concentrations of cardamonin. Cytokine levels were measured by ELISA and NO production was assessed using the Griess method. Inducible nitric oxide synthase expression and NF-κB activity were analyzed by immunofluorescence staining. Our results suggest that cardamonin inhibits TNF-α, IL-6 and NO production and downregulates iNOS expression and NF-κB activation. Collectively, our results highlight the ex vivo immunomodulatory effects of cardamonin on pro-inflammatory cytokine production and NO pathway in pSS patients. Therefore, cardamonin is a potential candidate for controlling inflammation during pSS.

Human regulatory B cells control the TFH cell response.

BACKGROUND: Follicular helper T (TFH) cells support terminal B-cell differentiation. Human regulatory B (Breg) cells modulate cellular responses, but their control of TFH cell-dependent humoral immune responses is unknown. OBJECTIVE: We sought to assess the role of Breg cells on TFH cell development and function. METHODS: Human T cells were polyclonally stimulated in the presence of IL-12 and IL-21 to generate TFH cells. They were cocultured with B cells to induce their terminal differentiation. Breg cells were included in these cultures, and their effects were evaluated by using flow cytometry and ELISA. RESULTS: B-cell lymphoma 6, IL-21, inducible costimulator, CXCR5, and programmed cell death protein 1 (PD-1) expressions increased on stimulated human T cells, characterizing TFH cell maturation. In cocultures they differentiated B cells into CD138+ plasma and IgD-CD27+ memory cells and triggered immunoglobulin secretions. Breg cells obtained by Toll-like receptor 9 and CD40 activation of B cells prevented TFH cell development. Added to TFH cell and B-cell cocultures, they inhibited B-cell differentiation, impeded immunoglobulin secretions, and expanded Foxp3+CXCR5+PD-1+ follicular regulatory T cells. Breg cells modulated IL-21 receptor expressions on TFH cells and B cells, and their suppressive activities involved CD40, CD80, CD86, and intercellular adhesion molecule interactions and required production of IL-10 and TGF-ß. CONCLUSION: Human Breg cells control TFH cell maturation, expand follicular regulatory T cells, and inhibit the TFH cell-mediated antibody secretion. These novel observations demonstrate a role for the Breg cell in germinal center reactions and suggest that deficient activities might impair the TFH cell-dependent control of humoral immunity and might lead to the development of aberrant autoimmune responses.

Interferon-ß inhibits inflammatory responses mediators via suppression of iNOS signaling pathway in PBMCs from patients with primary Sjögren's syndrome.

BACKGROUND: Primary Sjögren's syndrome (pSS) represents a chronic, systemic autoimmune disorder, characterized by lymphocytic infiltration of exocrine glands, inducing compromised secretory function and tissue destruction. Increasing evidence had revealed that inflammatory mediators, such as nitric oxide (NO) and pro-inflammatory cytokines, are critical in the development and perpetuation of pSS systemic manifestations. In our current study, we aimed to investigate the ex vivo immunomodulatory effect of interferon (IFN)-ß on iNOS expression, as well as on pro-inflammatory (tumor necrosis factor (TNF)-α, interleukin (IL)-6) and immunoregulatory (IL-10) cytokine production. Furthermore, we examined potential associations between the influence of IFN-ß treatment on NO production, and pSS clinical and serological manifestations. METHODS: In 41 pSS patients documented for their clinical and serological features, NO and cytokines levels were measured by the Griess method and enzyme-linked immunosorbent assay, respectively. Inducible nitric oxide synthase expression was analyzed by fluorescence immunostaining assay, using peripheral blood mononuclear cells (PBMCs) isolated from healthy controls and pSS patients. RESULTS: Our results revealed a strong down-modulating effect of IFN-ß in the secretion of pro-inflammatory mediators including TNF-α, IL-6, and NO production. Interestingly, IFN-ß exerts an increase in IL-10 levels. The most suppressive effect exerted by IFN-ß on NO production was importantly reported for patients with neurological manifestation. This immunomodulatory effect of IFN-ß on NO production is highly related to the decrease of inducible nitric oxide synthase (iNOS) expression. CONCLUSION: Our findings highlight a consistent ex vivo inhibitory effect of IFN-ß on pro-inflammatory cytokine production and NO pathway in pSS patients. Our data suggest that IFN-ß could represent a potential candidate for targeting inflammation during pSS.

Anti-alpha-actinin antibodies are part of the anti-cell membrane antibody spectrum that characterize patients with lupus nephritis.

Anti-membrane autoantibodies (MbA) have been reported in sera from patients with lupus nephritis (LN) but the targets of the MbA remain to be explored, which is the aim of the current study. Sera were collected from 40 patients with LN determined by renal biopsy, and from 30 systemic lupus erythematosus (SLE) patients without clinical evidence of LN. Thirty autoimmune disease control patients (rheumatoid arthritis, Sjögren's syndrome and systemic sclerosis), and 30 healthy controls were also included. Using flow cytometry, the presence of anti-MbA was explored revealing that IgG anti-MbA positivity was associated with LN (62.5% vs 13.3%) when compared to non-LN SLE patients, autoimmune disease patients (6.7%) and healthy controls (0%). Next, using purified plasma membrane fractions from human embryonic kidney (HEK) cells, the more prominent targets and their occurrence rates were located at 50 kDa, 60/65 kDa, 90 kDa, 110 kDa, 180 kDa and 220 kDa. Alpha-actinin (110 kDa) autoAb was characterized as a major target in LN patients positive for anti-MbA, and anti-MbA binding activity was reduced (36.9 ± 13.7%) in the presence of α-actinin. Laminin (200 kDa) was also characterized as a minor target, which was not the case for annexin A2 (36 kDa). Finally, anti-MbA IgG subclass analysis indicated a predominance of IgG2. In conclusion, IgG anti-MbA were detected at high levels in LN patients supporting a primary pathogenic role for anti-MbA and anti-MbA/α-actinin+ in LN that needs further research.

Intravenous immunoglobulin induces a functional silencing program similar to anergy in human B cells.

BACKGROUND: Chronic inflammatory and autoimmune diseases are largely due to inappropriate response of hyperactive or autoreactive B cells. These autoreactive B cells can evade central tolerance checkpoints and migrate to the periphery, where they would be silenced by anergy. Such anergic cells are characterized by B-cell receptor (BCR) desensitization and altered downstream signaling. OBJECTIVE: We sought to determine whether intravenous immunoglobulin (IVIg) induces a nonresponsive state of B cells and to address the similarities of this mechanism to those described in anergy. METHODS: Human B cells were stimulated with anti-IgM antibody, and effects of IVIg on several parameters, such as calcium release, tyrosine phosphorylation, BCR aggregation, BCR internalization, or transcriptional activity, were studied by using flow cytometry, confocal microscopy, Western blotting, and a quantitative PCR array. RESULTS: IVIg-treated B cells show defects in activating coreceptor expression, calcium signaling, and BCR aggregation on engagement by antigen. IVIg also induces suppression of phosphoinositide 3-kinase signaling, which plays a central role in determining B-cell fate. All these events ultimately lead to profound modifications in gene expression, resulting in long-term functional but reversible silencing of IVIg-treated B cells. CONCLUSION: Our findings provide insights into the effectiveness of IVIg in treating autoimmune or inflammatory pathologies associated with the loss of B-cell tolerance. Furthermore, these data provide a model to explore the complexity of positive versus negative selection in B cells.

TLR9 expressed on plasma membrane acts as a negative regulator of human B cell response.

Toll-like receptors (TLRs) are positioned at the interface between innate and adaptive immunity. Unlike others, those such as TLR9, that recognize nucleic acids, are confined to the endosomal compartment and are scarce on the cell surface. Here, we present evidence for TLR9 expression on the plasma membrane of B cells. In contrast to endosomal TLR9, cell surface TLR9 does not bind CpG-B oligodeoxynucleotides. After B cell-receptor (BCR) stimulation, TLR9 was translocated into lipid rafts with the BCR, suggesting that it could serve as a co-receptor for BCR. Nevertheless, stimulation of B cells with anti-TLR9 antibodies did not modify the BCR-induced responses despite up-regulation of tyrosine phosphorylation of proteins. However, CpG-B activation of B cells, acting synergistically with BCR signals, was inhibited by anti-TLR9 stimulation. Induction of CD25 expression and proliferation of B cells were thus down-regulated by the engagement of cell surface TLR9. Overall, our results indicate that TLR9 expressed on the plasma membrane of B cells might be a negative regulator of endosomal TLR9, and could provide a novel control by which activation of autoreactive B cells is restrained.

Specific forms of BAFF favor BAFF receptor-mediated epithelial cell survival.

Although B cell activating factor (BAFF) and its receptor BR3 are produced and expressed by many cells, their role has been restricted to the lymphocyte lineage. Using various techniques (RT-PCR, indirect immunofluorescence, flow cytometry analysis), we observed the expression of BR3 and the production of BAFF by the human salivary gland cell line, by epithelial cells from biopsies of Sjögren's syndrome patients and their controls, but also by salivary gland epithelial cells in culture. To decipher the role of BAFF and BR3 on epithelial cells, BAFF and BR3 were neutralized by blocking antibodies or RNA specific inhibitor (siBR3) and epithelial cell survival was analyzed. Blocking BR3 promotes epithelial cell apoptosis in vitro. This apoptosis resulted in the nuclear translocation of PKCδ. BAFF neutralization by various anti-BAFF antibodies leads to different effects depending on the antibody used suggesting that only some forms of BAFF are required for epithelial cell survival. Our study demonstrates that BR3 is involved in the survival of cultured epithelial cells due to an autocrine effect of BAFF. It also suggests that epithelial cells produce different forms of BAFF and that only some of them are responsible for this effect.

Maturation and function of human dendritic cells are regulated by B lymphocytes.

Mature dendritic cells (DCs) are stimulators of T-cell immune response, whereas immature DCs support T-cell tolerance. Murine B cells can inhibit the production of IL-12 by DCs and thereby hinder the inflammatory response. Notwithstanding the importance of this modulation, only a few studies are available in humans. Here, we have developed an in vitro model of cocultures to assess its significance. We establish that human activated B cells restrained the development of monocytes into immature DCs and their differentiation into mature DCs. In addition, they decreased the density of HLA-DR from mature DCs, the expression of CD80 and CD86 coactivation molecules, the production of IL-12p70 required for antigen presentation and Th1 differentiation, and inhibited the DC-induced T-cell proliferation. These modulations were mediated by CD19(+)IgD(low)CD38(+)CD24(low)CD27(-) B cells and needed direct cell-to-cell contacts that involved CD62L for the control of CD80 and CD86 expression and a soluble factor for the control of IL-12 production. Moreover, mature DCs from patients with systemic lupus erythematosus displayed insensitivity to the regulation of IL-12. Overall, it appears that human B cells can regulate DC maturation and function and that inefficient B-cell regulation may influence an improper balance between an effector inflammatory response and tolerance induction.

Contribution of salivary gland ultrasonography to the diagnosis of Sjögren's syndrome: toward new diagnostic criteria?

OBJECTIVE: To determine the accuracy of salivary gland ultrasonography (SGUS) for diagnosing primary Sjögren's syndrome (SS) and to suggest modifications of the American-European Consensus Group (AECG) classification criteria. METHODS: We conducted a cross-sectional study in a prospective cohort of patients with suspected primary SS that was established between 2006 and 2011. The echostructure of the bilateral parotid and submandibular glands was graded from 0 to 4, and the gland size was measured; blood flow to the parotid gland was assessed using Doppler waveform analysis. The reference standard was a clinical diagnosis of primary SS as determined by a group of experts blinded to the results of SGUS. Receiver operating characteristic (ROC) curve analysis was performed to compare the diagnostic value of the 0-4-point echostructure grade for each of the 4 major salivary glands, the sum of the grades for the 4 glands, and the highest grade among the 4 glands. RESULTS: Of the 158 patients in the study, 78 had a diagnosis of primary SS according to the experts, including 61 patients (78.2%) who met the AECG criteria. Doppler waveform analysis and gland size measurement showed poor diagnostic performance. The results of ROC curve analysis showed that the highest grade among the 4 glands provided the best diagnostic value. The optimal grade cutoff was 2 (62.8% sensitivity and 95.0% specificity). A weighted score was constructed using scores for the 5 variables selected by logistic regression analysis, as follows: (salivary flow×1.5)+(Schirmer's test×1.5)+(salivary gland biopsy×3)+(SSA/SSB×4.5)+(SGUS×2). According to ROC curve analysis, a score of ≥5 of 12.5 had 85.7% sensitivity and 94.9% specificity, compared with 77.9% sensitivity and 98.7% specificity for the AECG criteria. The addition of SGUS to the AECG criteria increased sensitivity to 87.0% but did not change specificity. CONCLUSION: Modifications of the AECG criteria, including the addition of a SGUS score, notably improved diagnostic performance.

Role of Fms-like tyrosine kinase 3 ligand as a potential biologic marker of lymphoma in primary Sjögren's syndrome.

OBJECTIVE: Patients with primary Sjögren's syndrome (SS) are at greater risk of developing lymphoma. This study was undertaken to evaluate whether the Fms-like tyrosine kinase 3 ligand (Flt-3L) might be associated with lymphoma in primary SS. METHODS: Serum levels of Flt-3L were measured in 369 patients with primary SS from the French Assessment of Systemic Signs and Evolution of Sjögren's Syndrome study cohort and in 10 patients with primary SS at the time of lymphoma diagnosis in an Italian cohort. Associations between increased levels of Flt-3L and a history of lymphoma, history of previously diagnosed criteria related to a high risk of lymphoma, and greater extent of disease activity were evaluated. RESULTS: Among patients with primary SS, higher levels of Flt-3L were significantly associated with a history of lymphoma (P = 0.0001). Previous markers for risk of lymphoma development, such as presence of purpura, low levels of C4, presence of lymphocytopenia, low levels of IgM, high levels of ß2 -microglobulin, and a higher primary SS disease activity score, were all associated with higher levels of Flt-3L. The levels of Flt-3L were also increased in serum obtained from patients with primary SS at the time of lymphoma diagnosis. Furthermore, the Flt-3L levels were elevated in the serum of 6 patients up to 94 months (mean 46 months) prior to the diagnosis of lymphoma. Receiver operating characteristic curve analysis showed that an Flt-3L level of 175 pg/ml was the ideal cutoff value for demonstrating an association with lymphoma (specificity 97.5%, sensitivity 44%, negative predictive value 97%). CONCLUSION: Flt-3L is associated with lymphoma in primary SS, and constitutes a good biologic marker. Higher levels of this cytokine are present several years before the diagnosis of lymphoma, and may be useful as a predictive marker of lymphoproliferative disorders in primary SS.

CD5 promotes IL-10 production in chronic lymphocytic leukemia B cells through STAT3 and NFAT2 activation.

B lymphocytes from chronic lymphocytic leukemia (CLL) display some CD5 transcripts for CD5 containing the known exon 1 (E1A) and other CD5 transcripts containing the new exon 1 (E1B). These malignant B cells, as well as B cell lines transfected with cDNA for E1A-cd5 or with cDNA for E1B-cd5 produce IL-10, raising the possibility that CD5 participates in the secretion of IL-10. We identified transcription factors involved in this production in CD5(+) B lymphocytes from CLL patients and in E1A-cd5-transfected or E1B-cd5-transfected Jok cells. STAT3 is activated via phosphorylation of serine 727 but also NFAT2 through its translocation into the nucleus. Chromatin immunoprecipitation experiments confirmed the role of STAT3 and allowed the discovery of a role for NFAT2 in IL-10 production. Both transcription factors bind not only to the enhancer of the Il-10 gene but also to the promoter of the Il-5 and Il-13 genes. Furthermore, transfection of B cell lines with E1A-cd5 or E1B-cd5 established that activation of STAT3 and NFAT2 is regulated by CD5. The same holds true for the production of IL-10, IL-5, and IL-13 and the expression of the receptors for these cytokines. This interpretation was confirmed by two experiments. In the first, downregulation of CD5 by small interfering RNAs lowered the production of IL-10. In the second experiment, transfection of the GFP-NFAT2 gene into B lymphocytes induced nuclear translocation of NFAT2 in CD5(+) but not in CD5(-) B cells. Thus, CD5 expression is associated with NFAT2 activity (and mildly STAT3 activity), indicating that CD5 controls IL-10 secretion.

TLR9 drives the development of transitional B cells towards the marginal zone pathway and promotes autoimmunity.

Maturation of B cells depends on environmental stimuli. Peripheral immature B cells develop into follicular pathway when antigenic stimulation is combined with T cell signals. Here, we wished to identify stimuli contributing to the development into marginal zone B cells known to be involved in autoimmune response. We found that TLR9 stimulation of transitional B cells induces proliferation and specific maturation into CD24(-) CD38(+) CD21(high) CD23(low) IgM(high) IgD(low) and Notch2(high) B cells characteristics of marginal zone B cells. Terminal differentiation into antibody-secreting cell associated with isotype switch commitment is also triggered which leads to a striking production of autoantibodies. Interestingly, mature B cells do not differentiate into marginal zone pathway following TLR9 stimulation, nor do transitional B cells under antigenic and T cell combined signals. These results suggest that transitional B cells are specifically sensitive to TLR9 stimulation to produce autoreactive marginal zone B cells.

Role of Toll-like receptors in primary Sjögren's syndrome with a special emphasis on B-cell maturation within exocrine tissues.

Be they follicular cells within the germinal centers (GCs) or marginal zone (MZ), all naïve mature B lymphocytes need tonic signaling to stay alive. We reasoned that the same holds true for those B lymphocytes that proliferate in the salivary glands (SGs) of patients with primary Sjögren's syndrome. Based on B cell infiltration, 11 SGs and three tonsil samples were selected for further examination. Tissue sections were stained using CD20 combined with CD10, CD21, CD27, CD38 or IgD. They were also laser-microdissected for quantitative RT-PCR of transcription factors, GC-specific activation-induced cytidine deaminase (AID) and TLR9. Some B cell aggregates proved to be real GCs according to their membrane markers, whereas others were clusters of transitional type II B cells. These contained mRNAs for Notch-2 and Blimp-1, but not for Pax-5, Bcl-6 and AID. Unanticipated was the finding of mRNAs for TLR9 in these clusters of MZ B-cells, but not in the real GCs. Not only do TLR9 deliver sufficiency of tonic signaling to keep B cells alive, but they also confer autoreactive B cells with an MZ-like phenotype. Thus, TLRs might be targets for forthcoming biotherapies.

Altered patterns of epigenetic changes in systemic lupus erythematosus and auto-antibody production: is there a link?

The prominent feature of immunological defects in systemic lupus erythematosus (SLE) is the production of autoantibodies (auto-Abs) to nuclear antigens including DNA, histones and RNP. In addition, there is growing evidence that epigenetic changes play a key role in the pathogenesis of SLE. Autoreactive CD4(+) T cells and B cells in patients with SLE have evidence of altered patterns of DNA methylation as well as post-translational modifications of histones and ribonucleoproteins (RNP). A key question that has emerged from these two characteristic features of SLE is whether the two processes are linked. New data provide support for such a link. For example, there is evidence that hypomethylated DNA is immunogenic, that anti-histone auto-Abs in patients with SLE bind epigenetic-sensitive hot spots and that epigenetically-modified RNP-derived peptides can modulate lupus disease. All in all, the available evidence indicates that a better understanding of dysregulation in epigenetics in SLE may offer opportunities to develop new biomarkers and novel therapeutic strategies.

The complexity of the BAFF TNF-family members: implications for autoimmunity.

The B-cell activating factor belonging to the tumor-necrosis factor family BAFF contributes to autoimmune disorders. As such, BAFF might become a therapeutic target. However, this molecule has pleiotropic effects that are as numerous as they are varied. The real effect of each form (spliced, glycosylated, membrane bound, soluble, homotrimerized, heterotrimerized, multimerized) has not been well characterized yet. Consequently, conflicting results, regarding the serum concentrations of BAFF or its functional effect, exist in literature. BAFF quantification based on ELISA commercial kits was indeed found to be inaccurate. The complexity of the various forms of BAFF will be reviewed by focusing on the different structural aspects of the molecule. These data have particular implications for autoimmunity, not only because of the role of these factors on B cell growth and survival, but also their influence on the onset and severity of several autoimmune diseases.

Low levels of vitamin-D are associated with neuropathy and lymphoma among patients with Sjögren's syndrome.

BACKGROUND/PURPOSE: Primary Sjögren's syndrome (SS) is a chronic autoimmune disease primarily involving the exocrine glands. The clinical picture of SS ranges from exocrinopathy to systemic disease affecting the lung, kidney, liver, skin, musculockeletal and nervous systems. The morbidity of SS is mainly determined by extraglandular disease and increased prevalence of lymphoma. Environmental and hormonal factors, such as vitamin-D may play a role in the pathogenic process and disease expression. Thus, we aimed to evaluate levels of vitamin-D and their association with manifestations of SS. METHODS: Vitamin-D levels were determined in 176 primary SS patients and 163 matched healthy volunteers utilizing the LIAISON chemiluminescent immunoassays (DiaSorin-Italy). A correlation between vitamin-D levels and clinical and serological manifestations of SS was performed. RESULTS: Mean vitamin-D levels were comparable between SS patients and control 21.2 ± 9.4 ng/ml and 22.4 ± 10 ng/ml, respectively. Peripheral neuropathy was diagnosed in 23% of SS patients and associated with lower vitamin-D levels (18.6 ± 5.5 ng/ml vs. 22.6±8 ng/ml (p = 0.04)). Lymphoma was diagnosed in 4.3% of SS patients, who had lower levels of vitamin-D (13.2 ± 6.25 ng/ml), compared to SS patients without lymphoma (22 ± 8 ng/ml), (p = 0.03). Other clinical and serological manifestations did not correlate with vitamin-D status. CONCLUSIONS: In this study, low levels of vitamin-D correlated with the presence of peripheral neuropathy and lymphoma among SS patients. The link between vitamin-D and neuropathy or lymphoma was reported in other conditions, and may support a role for vitamin-D in the pathogenesis of these processes. Plausible beneficial effect for vitamin-D supplementation may thus be suggested.

IVIg modulates BCR signaling through CD22 and promotes apoptosis in mature human B lymphocytes.

Among various mechanisms for interactions with B cells, intravenous immunoglobulin (IVIg) may operate through the insertion of its Fc part into the Fc-γ receptor, or the binding of its sialic acid (SA)-bearing glycans to the negatively regulating CD22 lectin. It appeared that IVIg reduces B lymphocyte viability in a dose- and time-dependent manner. Furthermore, we show by confocal microscopy that SA-positive IgG, but not SA-negative IgG bind to CD22. This interaction reduces the strength of B-cell receptor-mediated signaling trough down-regulating tyrosine phosphorylation of Lyn and the B-cell linker proteins, and up-regulating phospholipase Cγ2 activation. This cascade resulted in a sustained activation of Erk 1/2 and arrest of the cell cycle at the G(1) phase. These changes may be accounted for the efficacy of IVIg in autoimmune diseases.

Membrane microdomain sphingolipids are required for anti-CD20-induced death of chronic lymphocytic leukemia B cells.

BACKGROUND: Chronic lymphocytic leukemia remains incurable, despite the addition of rituximab to chemotherapy as an available means of treatment. The resistance of certain patients to this monoclonal antibody prompted us to set up in vitro studies of another CD20-specific monoclonal antibody, B1 (later termed tositumomab). We hypothesized that the membrane lipid organization of leukemic B cells might be instrumental in the cells' sensitivity to the B1 monoclonal antibody. DESIGN AND METHODS: B lymphocytes from 36 patients with chronic lymphocytic leukemia and 13 patients with non-Hodgkin's lymphoma were investigated for B1-triggered cell death. Membrane components, such as sphingomyelin and ganglioside M1, were investigated by flow cytometry, immunofluorescence and co-immunoprecipitation, together with the Csk-binding protein. RESULTS: Chronic lymphocytic leukemia patients segregated into two groups: B cells from one group were sensitive to B1, whereas those from the second group were not. Further results ascribed the resistance of these latter cases to a defective recruitment of Csk-binding protein, resulting in a lack of sphingomyelin and ganglioside M1 at the outer leaflet of the plasma membrane of their malignant B cells. Sphingolipids were indeed retained in the cytoplasm, because of lowered activity of P-glycoprotein. Supporting this mechanism, rifampicin, an inducer of P-glycoprotein, improved the activity of this transmembrane efflux pump, normalized the quantity of sphingomyelin within the membrane, and thereby restored the efficacy of the B1 monoclonal antibody in the formerly B1-resistant cases of chronic lymphocytic leukemia. CONCLUSIONS: The lipid organization of membranes of B cells from patients with chronic lymphocytic leukemia differs from one patient to another. In practice, given the relevance of the membrane lipid distribution to the efficacy of biotherapies, this observation is of potential importance.

Identification of patients with indolent B cell lymphoma sensitive to rituximab monotherapy.

The potential predictive value of tumor bulk, genetic, and immunological variants in patients with low-grade non-Hodgkin's lymphoma to respond to treatment with rituximab (RTX) monotherapy was evaluated. Thus, the value of assessing the effect of 18-fluoro-desoxy-D-glucose (FDG) uptake on PET scan, polymorphisms in Fc gamma receptor (FcγR) IIIa-158, FcγRIIa-131, and C1qA-276 genes in predicting the response to treatment were evaluated in 50 low-grade non-Hodgkin's lymphoma patients. The influence of RTX pharmacokinetics, plasma levels of the B cell-activating factor (BAFF), and human antichimeric antibodies was also investigated. The therapeutic response was evaluated 10 weeks after treatment using revised Cheson's criteria. Lower maximal standardized uptake values (SUV(max)) at baseline were predictive of complete response. FcγRIIIa-158 polymorphism was also associated with complete response to RTX confirming previous findings, whereas polymorphisms in the FcγRIIa-131 and C1qA-276 genes were not. Lower blood levels of RTX were observed in males, but the effectiveness of RTX in males and females was the same. BAFF was not detectable in plasma before or after treatment, and no patients developed human antichimeric antibodies. Low-grade non-Hodgkin's lymphoma patients with a low SUV(max) at baseline and an FcγRIIIa-158 V/V genotype generally had a complete response to RTX.

CD5 expression in B cells from patients with systemic lupus erythematosus.

The recently recognized importance of B cells in systemic lupus erythematosus (SLE) raises the question as to whether those expressing CD5 predominate over the remaining B lymphocytes in the pathophysiology of this disease. Owing to their B B-cell receptor (BCR) polyspecificity, autoantibody production has been originally ascribed to CD5-positive B1 lymphocytes. Instead, it has since been established that high-affinity autoantibodies derive from CD5-negative B2 cells. Even worse, in the light of current findings, CD5-positive B cells have been considered to play a paradoxical role in preventing, rather than inducing, autoimmunity. In this context, there is evidence that the membrane expression of CD5 is regulated, and, to this end, a genetic mechanism has been described, based on the selection between exon 1A (E1A) and exon 1B (E1B). The full-length protein variant, encoded by E1A-cd5, translocates the phosphatase SHP-1 to the vicinity of the BCR, raises its threshold, and thereby limits the response of autoreactive B cells. In contrast, the truncated variant, encoded by E1B-cd5, remains in the cytoplasm, along with SHP1. Normally, EIB E1B is silenced by methylation and its product degraded in the proteosomes. Hence, a defect in the DNA methyl transfer favors the development of SLE, by preventing the effects of SHP-1.