Sustained Remission Without Corticosteroids Among Patients With Pemphigus Who Had Rituximab as First-Line Therapy: Follow-Up of the Ritux 3 Trial.

Importance: The Ritux 3 trial demonstrated the short-term efficacy and safety of first-line treatment with rituximab compared with a standard corticosteroid regimen in pemphigus. No data on the long-term follow-up of patients who received rituximab as first line are available. Objective: To assess the long-term efficacy and safety of the Ritux 3 treatment regimen. Design, Setting, and Participants: This 7-year follow-up study of the Ritux 3 trial included patients with pemphigus from 25 dermatology departments in France from January 1, 2010, to December 31, 2015. Exposure: Patients were initially randomized in the rituximab plus prednisone group or prednisone-alone group. Main outcomes and measures: The primary outcome was the 5- and 7-year disease-free survival (DFS) without corticosteroids, assessed by Kaplan-Meier curves. Secondary outcomes were occurrence of relapse, occurrence of severe adverse events (SAEs), and evolution of antidesmoglein (Dsg) antibody enzyme-linked immunosorbent assay values to predict long-term relapse. Results: Of the 90 patients in the Ritux 3 trial, 83 were evaluated at the end of follow-up study visit (44 in the rituximab plus prednisone group; 39 in the prednisone-alone group) with a median (IQR) follow-up of 87.3 (79.1-97.5) months. Forty-three patients (93%) from the rituximab plus prednisone and 17 patients (39%) from the prednisone-alone group had achieved complete remission without corticosteroids at any time during the follow-up. Patients from the rituximab group had much longer 5- and 7-year DFS without corticosteroids than patients from the prednisone-alone group (76.7% and 72.1% vs 35.3% and 35.3%, respectively; P < .001), and had about half the relapses (42.2% vs 83.7%; P < .001). Patients who received rituximab as second-line treatment had shorter DFS than patients treated as first line (P = .007). Fewer SAEs were reported in the rituximab plus prednisone group compared with the prednisone-alone group, 31 vs 58 respectively, corresponding to 0.67 and 1.32 SAEs per patient, respectively (P = .003). The combination of anti-Dsg1 values of 20 or more IU/mL and/or anti-Dsg3 values of 48 or more IU/mL yielded 0.83 positive predictive value and 0.94 negative predictive value to predict long-term relapse. Conclusions and Relevance: In this secondary analysis of the Ritux 3 trail, first-line treatment of patients with pemphigus with the Ritux 3 regimen was associated with long-term sustained complete remission without corticosteroid therapy without any additional maintenance infusion of rituximab.

Modifications of the BAFF/BAFF-Receptor Axis in Patients With Pemphigus Treated With Rituximab Versus Standard Corticosteroid Regimen.

The efficacy of the B-cell-depleting agent rituximab has been reported in immune diseases but relapses are frequent, suggesting the need for repeated infusions. The B-cell activating factor (BAFF) is an important factor for B cell survival, class switch recombination and selection of autoreactive B cells, as well as maintaining long-lived plasma cells. It has been hypothesized that relapses after rituximab might be due to the increase of serum BAFF levels. From the Ritux3 trial, we showed that baseline serum BAFF levels were higher in pemphigus patients than in healthy donors (308 ± 13 pg/mL versus 252 ± 28 pg/mL, p=0.037) and in patients with early relapse compared who didn't (368 ± 92 vs 297 ± 118 pg/mL, p=0.036). Rituximab and high doses of CS alone have different effects on the BAFF/BAFF-R axis. Rituximab led to an increase of BAFF levels associated to a decreased mRNA (Day 0: 12.3 ± 7.6 AU vs Month 36: 3.3 ± 4.3 AU, p=0.01) and mean fluorescence intensity of BAFF-R in non-autoreactive (Day 0: 3232 vs Month 36: 1527, mean difference: 1705, 95%CI: 624 to 2786; p=0.002) as well as on reappearing autoreactive DSG-specific B cells (Day 0: 3873 vs Month 36: 2688, mean difference: 1185, 95%CI: -380 to 2750; p=0.20). Starting high doses of corticosteroids allowed a transitory decrease of serum BAFF levels that re-increased after doses tapering whereas it did not modify BAFF-R expression in autoreactive and non-autoreactive B cells. Our results suggest that the activation of autoreactive B cells at the onset of pemphigus is likely to be related to the presence of high BAFF serum levels and that the decreased BAFF-R expression after rituximab might be responsible for the delayed generation of memory B cells, resulting in a rather long period of mild pemphigus activity after rituximab therapy. Conversely, the incomplete B cell depletion and persistent BAFF-R expression associated with high BAFF serum levels might explain the high number of relapses in patients treated with CS alone.

A Subset of Type I Conventional Dendritic Cells Controls Cutaneous Bacterial Infections through VEGFα-Mediated Recruitment of Neutrophils.

Skin conventional dendritic cells (cDCs) exist as two distinct subsets, cDC1s and cDC2s, which maintain the balance of immunity to pathogens and tolerance to self and microbiota. Here, we examined the roles of dermal cDC1s and cDC2s during bacterial infection, notably Propionibacterium acnes (P. acnes). cDC1s, but not cDC2s, regulated the magnitude of the immune response to P. acnes in the murine dermis by controlling neutrophil recruitment to the inflamed site and survival and function therein. Single-cell mRNA sequencing revealed that this regulation relied on secretion of the cytokine vascular endothelial growth factor α (VEGF-α) by a minor subset of activated EpCAM+CD59+Ly-6D+ cDC1s. Neutrophil recruitment by dermal cDC1s was also observed during S. aureus, bacillus Calmette-Guérin (BCG), or E. coli infection, as well as in a model of bacterial insult in human skin. Thus, skin cDC1s are essential regulators of the innate response in cutaneous immunity and have roles beyond classical antigen presentation.

B-cell depletion induces a shift in self antigen specific B-cell repertoire and cytokine pattern in patients with bullous pemphigoid.

Bullous Pemphigoid is the most common auto-immune bullous skin disease. It is characterized by the production of auto-antibodies directed against 2 proteins of the hemi-desmosome (BP180 and BP230). We assessed the efficacy and mechanisms of action of rituximab, an anti-CD20 monoclonal antibody, in 17 patients with severe and relapsing type of bullous pemphigoid. The phenotype, cytokine gene expression, and rearrangement of BP180-specific B-cell receptor genes were performed over 2 years following treatment. At the end of the study, 5 patients had died, 3 had withdrawn from the study, and 9 patients were in complete remission. The one- and two-year relapse rates were 44.1% (95% Confidence Interval (CI): 21.0-76.0%) and 66.5%, (95% CI: 38.4-91.4%), respectively. Phenotypic analyses confirmed dramatic B-cell depletion, which lasted for 9 to 12 months. The ELISA values of serum anti-BP180 antibodies and the frequency of BP180-specific circulating B cells decreased dramatically following treatment, which paralleled the improvement of skin lesions. During B-cell reconstitution, a polyclonal IgM repertoire appeared and a shift in the rearrangement of the B-cell receptor genes of BP180-specific circulating B cells was observed. Concurrently, we observed a decrease of IL-15, IL-6 and TNFα expressing BP180-specific B cells, and the emergence of IL-10 and IL-1RA-expressing BP180-specific IgM+ B cells in patients in complete remission off therapy, suggesting the functional plasticity of BP180-specific auto-immune B cells after rituximab treatment.

First-line rituximab combined with short-term prednisone versus prednisone alone for the treatment of pemphigus (Ritux 3): a prospective, multicentre, parallel-group, open-label randomised trial.

BACKGROUND: High doses of corticosteroids are considered the standard treatment for pemphigus. Because long-term corticosteroid treatment can cause severe and even life-threatening side-effects in patients with this disease, we assessed whether first-line use of rituximab as adjuvant therapy could improve the proportion of patients achieving complete remission off-therapy, compared with corticosteroid treatment alone, while decreasing treatment side-effects of corticosteroids. METHODS: We did a prospective, multicentre, parallel-group, open-label, randomised trial in 25 dermatology hospital departments in France (Ritux 3). Eligible participants were patients with newly diagnosed pemphigus aged 18-80 years being treated for the first time (not at the time of a relapse). We randomly assigned participants (1:1) to receive either oral prednisone alone, 1·0 or 1·5 mg/kg per day tapered over 12 or 18 months (prednisone alone group), or 1000 mg of intravenous rituximab on days 0 and 14, and 500 mg at months 12 and 18, combined with a short-term prednisone regimen, 0·5 or 1·0 mg/kg per day tapered over 3 or 6 months (rituximab plus short-term prednisone group). Follow-up was for 3 years (study visits were scheduled weekly during the first month of the study, then monthly until month 24, then an additional visit at month 36). Treatment was assigned through central computer-generated randomisation, with stratification according to disease-severity (severe or moderate, based on Harman's criteria). The primary endpoint was the proportion of patients who achieved complete remission off-therapy at month 24 (intention-to-treat analysis). This study is registered with ClinicalTrials.gov, number NCT00784589. FINDINGS: Between May 10, 2010, and Dec 7, 2012, we enrolled 91 patients and randomly assigned 90 to treatment (90 were analysed; 1 patient withdrew consent before the random assignment). At month 24, 41 (89%) of 46 patients assigned to rituximab plus short-term prednisone were in complete remission off-therapy versus 15 (34%) of 44 assigned to prednisone alone (absolute difference 55 percentage points, 95% CI 38·4-71·7; p<0·0001. This difference corresponded to a relative risk of success of 2·61 (95% CI 1·71-3·99, p<0·0001), corresponding to 1·82 patients (95% CI 1·39-2·60) who would need to be treated with rituximab plus prednisone (rather than prednisone alone) for one additional success. No patient died during the study. More severe adverse events of grade 3-4 were reported in the prednisone-alone group (53 events in 29 patients; mean 1·20 [SD 1·25]) than in the rituximab plus prednisone group (27 events in 16 patients; mean 0·59 [1·15]; p=0·0021). The most common of these events in both groups were diabetes and endocrine disorder (11 [21%] with prednisone alone vs six [22%] with rituximab plus prednisone), myopathy (ten [19%] vs three [11%]), and bone disorders (five [9%] vs five [19%]). INTERPRETATION: Data from our trial suggest that first-line use of rituximab plus short-term prednisone for patients with pemphigus is more effective than using prednisone alone, with fewer adverse events. FUNDING: French Ministry of Health, French Society of Dermatology, Roche.

Soluble alpha-enolase activates monocytes by CD14-dependent TLR4 signalling pathway and exhibits a dual function.

Rheumatoid arthritis (RA) is the most common form of chronic inflammatory rheumatism. Identifying auto-antigens targeted by RA auto-antibodies is of major interest. Alpha-enolase (ENO1) is considered to be a pivotal auto-antigen in early RA but its pathophysiologic role remains unknown. The main objective of this study was to investigate the in vitro effects of soluble ENO1 on peripheral blood mononuclear cells (PBMC) from healthy donors and RA patients in order to determine the potential pathogenic role of ENO1. ELISA, transcriptomic analysis, experiments of receptor inhibition and flow cytometry analysis were performed to determine the effect, the target cell population and the receptor of ENO1. We showed that ENO1 has the ability to induce early production of pro-inflammatory cytokines and chemokines with delayed production of IL-10 and to activate the innate immune system. We demonstrated that ENO1 binds mainly to monocytes and activates the CD14-dependent TLR4 pathway both in healthy subjects and in RA patients. Our results establish for the first time that ENO1 is able to activate in vitro the CD14-dependent TLR4 pathway on monocytes involving a dual mechanism firstly pro-inflammatory and secondly anti-inflammatory. These results contribute to elucidating the role of this auto-antigen in the pathophysiologic mechanisms of RA.

Direct Toll-Like Receptor 8 signaling increases the functional avidity of human CD8+ T lymphocytes generated for adoptive T cell therapy strategies.

Adoptive transfer of in vitro activated and expanded antigen-specific cytotoxic T lymphocytes (CTLs) is a promising therapeutic strategy for infectious diseases and cancers. Obtaining in vitro a sufficient amount of highly specific cytotoxic cells and capable of retaining cytotoxic activity in vivo remains problematic. We studied the role of Toll-Like Receptor-8 (TLR8) engagement on peripheral CTLs activated with melanoma antigen MART-1-expressing artificial antigen-presenting cells (AAPCs). After a 3-week co-culture, 3-27% of specific CTLs were consistently obtained. CTLs expressed TLR8 in the intracellular compartment and at the cell surface. Specific CTLs activated with a TLR8 agonist (CL075) 24 h before the end of the culture displayed neither any change in their production levels of molecules involved in cytotoxicity (IFN-γ, Granzyme B, and TNF-α) nor major significant change in their cell surface phenotype. However, these TLR8-stimulated lymphocytes displayed increased cytotoxic activity against specific peptide-pulsed target cells related to an increase in specific anti-melanoma CTL functional avidity. TLR8 engagement on CTLs could, therefore, be useful in different immunotherapy strategies.

Human regulatory B cells combine phenotypic and genetic hallmarks with a distinct differentiation fate.

Regulatory B cells (B-reg) produce IL-10 and suppress inflammation in both mice and humans, but limited data on the phenotype and function of these cells have precluded detailed assessment of their contribution to host immunity. In this article, we report that human B-reg cannot be defined based on a phenotype composed of conventional B cell markers, and that IL-10 production can be elicited in both the CD27(+) memory population and naive B cell subset after only a brief stimulation in vitro. We therefore sought to obtain a better definition of IL-10-producing human B-regs using a multiparameter analysis of B cell phenotype, function, and gene expression profile. Exposure to CpG and anti-Ig are the most potent stimuli for IL-10 secretion in human B cells, but microarray analysis revealed that human B cells cotreated with these reagents resulted in only ∼0.7% of genes being differentially expressed between IL-10(+) and IL-10(-) cells. Instead, connectivity map analysis revealed that IL-10-secreting B cells are those undergoing specific differentiation toward a germinal center fate, and we identified a CD11c(+) B cell subset that was not capable of producing IL-10 even under optimal conditions. Our findings will assist in the identification of a broader range of human pro-B-reg populations that may represent novel targets for immunotherapy.

Lack of expression of an alternative CD20 transcript variant in circulating B cells from patients with pemphigus.

We have identified a spliced mRNA transcript of CD20 (named D393-CD20) which was associated with resistance to RTX in primary B cell from patients with lymphoma and leukaemia. In the present work, we wished to investigate whether D393-CD20 variant was expressed by B cells from patients with pemphigus. Ten patients with bullous pemphigoid and twenty-five patients with pemphigus were included. All patients were responder to conventional immunosuppressive agents or rituximab (n = 11). Efficacy of B-cell activation by pokeweed mitogen was assessed by CD86 expression using a FACS Canto II flow cytometer. mRNA CD20 expression study was then performed using RT-PCR assay allowing first to discriminate wild-type (wt)-CD20 and D393-CD20 transcript. Although wt-CD20 expression was always detected, we were unable to detect D393-CD20, even after B-cell activation or RTX treatment. Our results suggest that D393-CD20 transcript may be a molecular marker of B-cell malignancies rather than autoimmune disease like pemphigus. Further study of RTX non-responders or non-escaping PV patients is thus still required to appreciate whether D393-CD20 expression may be detected under the pressure of RTX therapy.

Drug Reaction with Eosinophilia and Systemic Symptoms: an update on pathogenesis.

The syndrome termed 'Drug Reaction with Eosinophilia and Systemic Symptoms' (DRESS) is an unpredictable, life-threatening condition associated with adverse reactions to therapy. Although the etiology of DRESS is poorly understood, genetic susceptibility markers have been identified within the HLA complex and there are several prevailing models of pathogenesis. Modification of host antigens by haptens (drugs or their metabolites), or non-covalent drug binding to endogenous proteins (the p-i concept), may drive pro-inflammatory immune responses in patients. Alternatively, a viral trigger for DRESS has been proposed based on the concomitant detection of herpesviruses and the recent demonstration of Epstein-Barr virus-specific immune responses in DRESS patients. In the present review, we discuss the latest findings concerning the pathogenesis of drug reactions and known risk factors for DRESS.

The DRESS syndrome: a literature review.

The Drug Reaction with Eosinophilia and Systemic Symptom (DRESS) is a severe adverse drug-induced reaction. Diagnosing DRESS is challenging due to the diversity of cutaneous eruption and organs involved. We used the RegiSCAR scoring system that grades DRESS cases as "no," "possible," "probable," or "definite" to classify cases reported in the literature. We also analyzed the clinical course and treatments of the cases. A total of 44 drugs were associated with the 172 cases reported between January 1997 and May 2009 in PubMed and MEDLINE. The most frequently reported drug was carbamazepine, and the vast majority of cases were classified as "probable/definite" DRESS cases. Hypereosinophilia, liver involvement, fever, and lymphadenopathy were significantly associated with "probable/definite" DRESS cases, whereas skin rash was described in almost all of the cases, including "possible cases." Culprit drug withdrawal and corticosteroids constituted the mainstay of DRESS treatment. The outcome was death in 9 cases. However, no predictive factors for serious cases were found. This better knowledge of DRESS may contribute to improve the diagnosis and management of this syndrome in clinical practice.

Drug reaction with eosinophilia and systemic symptoms (DRESS): a multiorgan antiviral T cell response.

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe, drug-induced reaction that involves both the skin and the viscera. Evidence for reactivation of herpes family viruses has been seen in some DRESS patients. To understand the immunological components of DRESS and their relationship to viral reactivation, we prospectively assessed 40 patients exhibiting DRESS in response to carbamazepine, allopurinol, or sulfamethoxazole. Peripheral blood T lymphocytes from the patients were evaluated for phenotype, cytokine secretion, and repertoire of CD4+ and CD8+ and for viral reactivation. We found Epstein-Barr virus (EBV), human herpes virus 6 (HHV-6), or HHV-7 reactivation in 76% of the patients. In all patients, circulating CD8+ T lymphocytes were activated, exhibited increased cutaneous homing markers, and secreted large amounts of tumor necrosis factor-alpha and interferon-gamma. The production of these cytokines was particularly high in patients with the most severe visceral involvement. In addition, expanded populations of CD8+ T lymphocytes sharing the same T cell receptor repertoire were detected in the blood, skin, liver, and lungs of patients. Nearly half of these expanded blood CD8+ T lymphocytes specifically recognized one of several EBV epitopes. Finally, we found that the culprit drugs triggered the production of EBV in patients' EBV-transformed B lymphocytes. Thus, cutaneous and visceral symptoms of DRESS are mediated by activated CD8+ T lymphocytes, which are largely directed against herpes viruses such as EBV.

Critical role of TLR2 and TLR4 in autoantibody production and glomerulonephritis in lpr mutation-induced mouse lupus.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by pathogenic autoantibodies directed against nuclear Ags and immune complex deposits in damaged organs. Environmental factors have been thought to play a role in the onset of the disease. The recognition of these factors is mediated by TLRs, in particular TLR2 and TLR4 which bind pathogen-associated molecular patterns of Gram(+) and Gram(-) bacteria, respectively. We attempted to determine the role of these TLRs in SLE by creating TLR2- or TLR4-deficient C57BL/6(lpr/lpr) mice. These mice developed a less severe disease and fewer immunological alterations. Indeed, in C57BL/6(lpr/lpr)-TLR2 or -TLR4-deficient mice, glomerular IgG deposits and mesangial cell proliferation were dramatically decreased and antinuclear, anti-dsDNA, and anti-cardiolipin autoantibody titers were significantly reduced. However, the response against nucleosome remained unaffected, indicating a role of TLR2 and TLR4 in the production of Abs directed against only certain categories of SLE-related autoantigens. Analysis of B cell phenotype showed a significant reduction of marginal zone B cells, particularly in C57BL/6(lpr/lpr)-TLR4-deficient mice, suggesting an important role of TLR4 in the sustained activation of these cells likely involved in autoantibody production. Interestingly, the lack of TLR4 also affected the production of cytokines involved in the development of lupus disease.

Toll-like receptors 4 contribute to endothelial injury and inflammation in hemorrhagic shock in mice.

OBJECTIVE: Hemorrhagic shock followed by resuscitation (HS/R) promotes organ injury by priming cells of the innate immune system for inflammatory response. Toll-like receptors (TLRs) play an important role in signal transduction in shock/resuscitation conditions. Because proinflammatory mediators are a critical event in mesenteric endothelial injury induced by HS/R, we assessed the role of TLR4 or TLR2 in this setting. DESIGN: Laboratory investigation. SETTING: Research laboratory at Rouen University Medical School. SUBJECTS: Male wild-type, TLR4(-/-) and TLR2(-/-) mice with the same C57BL/6 background. INTERVENTIONS: Mice were submitted to 30 minutes hemorrhagic shock followed by 1 hour resuscitation, after which mesenteric endothelial dysfunction, microvascular injury, and TNF[alpha] production were assessed. MEASUREMENTS AND MAIN RESULTS: HS/R markedly decreased nitric oxide-mediated mesenteric relaxations induced by acetylcholine, assessed ex vivo on a myograph. By contrast, in TLR4-deficient mice, HS/R did not impair the nitric oxide-mediated responses to acetylcholine. No protection was observed in TLR2-deficient mice. TLR4-deficient mice also displayed a significant reduction in fluid resuscitation and TNF[alpha] systemic production. CONCLUSIONS: TLR4 contributes to mesenteric endothelial dysfunction after hemorrhagic shock. This early TLR4-induced vascular injury may be an important trigger of the systemic inflammatory response occurring in this disease.

B-cell depletion immunotherapy in pemphigus: effects on cellular and humoral immune responses.

Pemphigus are B-cell-mediated autoimmune diseases affecting skin and mucous membranes. They are characterized by the production of pathogenic autoantibodies directed against desmogleins (Dsg). In this prospective study, we treated 21 pemphigus patients with rituximab and analyzed immunological modifications induced by anti-CD20 immunotherapy. The total depletion of peripheral B cells led to a significant decrease of total serum IgM but not IgG levels. The B-cell depletion was followed by a progressive re-emergence of naive blood B lymphocytes, with one-third of them expressing a transitional CD19+CD38(high)CD24(high) phenotype. In most patients, clinical response to rituximab was closely related to the evolution of anti-Dsg autoantibodies that decreased in patients who achieved complete remission, whereas they remained unchanged or reincreased in relapsing patients. In contrast, serum antimicrobial IgG remained stable after rituximab treatment. B-cell repertoire analysis of three patients using immunoscope showed distortions of VH-IgM and VH-IgG immunoscope profiles before treatment, particularly clonal and oligoclonal expansions in some VH families, which were not found after B-cell reconstitution, following anti-CD20 immunotherapy. The depletion of autoreactive B cells leading to the elimination of anti-Dsg autoantibodies in most remitted patients and the restoration of a diverse B-cell repertoire by naive B lymphocytes may provide an explanation for the long-lasting efficacy of rituximab in pemphigus patients.

Expression, subcellular localization and cytokinic modulation of Toll-like receptors (TLRs) in normal human keratinocytes: TLR2 up-regulation in psoriatic skin.

The aim of the research described here was to investigate the expression of Toll-like receptors (TLRs) in normal human keratinocytes, to study its modulation by proinflammatory cytokines, and to characterize the function of the latter within the epidermis. Our results demonstrate that normal human keratinocytes may present an intra-cytoplasmic expression of TLR2, TLR3, and TLR4. Exposure of keratinocytes to IFN-gamma and TNF-alpha increased intra-cytoplasmic expression and led to partial translocation at the cell surface. Keratinocyte activation by TLR2, TLR3, and TLR4 ligands led to the nuclear translocation of NF-kappab and the release of proinflammatory cytokines TNF-alpha and IL-8. In immunochemistry analysis, psoriatic skin showed a strong over-expression of TLR2 in the epidermis compared with normal skin. Our results thus demonstrate large TLR expression in keratinocytes and the functionality of TLRs 2, 3, and 4. TLR2 over-expression in psoriatic skin provides new insights into TLR implication in the pathogenesis of psoriasis, through inappropriate stimulation by infectious or endogen ligands.

Role of TLR9 in anti-nucleosome and anti-DNA antibody production in lpr mutation-induced murine lupus.

Systemic lupus erythematosus is characterized by the production of autoantibodies directed against nuclear Ags, including nucleosome and DNA. TLR9 is thought to play a role in the production of these autoantibodies through the capacity of nuclear immunogenic particles to interact both with BCR and TLR9. To determine the role of TLR9 in SLE, C57BL/6-lpr/lpr-TLR9(-/-) and TLR9(+/+) mice were analyzed. The abrogation of TLR9 totally impaired the production of anti-nucleosome Abs, whereas no difference was observed in the frequency of anti-dsDNA autoantibodies whose titer was strikingly higher in TLR9(-/-) mice. In addition a higher rate of mesangial proliferation was observed in the kidney of TLR9-deficient animals. These results indicate that in C57BL/6-lpr/lpr mice, TLR9 is absolutely required for the anti-nucleosome Ab response but not for anti-dsDNA Ab production which is involved in mesangial proliferation.