CD20 B-cell Research Articles

Efficacy and safety of rituximab for myasthenia gravis: a systematic review and meta-analysis.

Myasthenia gravis is an autoimmune disorder of the neuromuscular junction caused by circulating antibodies specific for the post-synaptic acetylcholine receptor or, in a minority of cases, for the muscle-specific tyrosine-kinase and the low-density lipoprotein receptor-related protein 4. A wide range of symptomatic and immunosuppressive treatments is currently available for MG patients with variable outcome. However, most immunosuppressive treatments are characterized by delayed onset of action and in some cases are not sufficient to induce stable remission of the disease. Rituximab (RTX) is a chimaeric monoclonal antibody specific for the CD20 B-cell surface antigen. Recent studies have provided evidence that RTX may be an effective treatment for patients with myasthenia gravis (MG) who are refractory to standardized immunosuppressive therapy. We performed a systematic review and a meta-analysis of the efficacy and safety of RTX in myasthenia gravis considering the potential predictive factors related to patients' response to RTX in this disease.

Analysis of rituximab’s usage for the treatment of pediatric systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease characterized by chronic inflammation that potentially leads to organ damage. Severe manifestations make the management of SLE difficult and challenging. Nonsteroidal antiinflammatory drugs (NSAIDs), antimalarial drugs, glucocorticoids, immunosuppressive and citotoxic agents are the mainstays of treatment. Unfortunately, these agents are related to a vast toxicity. For an amount of patients, these approaches arent enough to achieve disease activity control, especially in those with cytopenia, nephritis and neuropsychiatric lupus. For these cases, Rituximab (RTX) – a chimeric mouse/human monoclonal antibody specific for human CD20 B-cell – has been widely prescribed. It is known that B-cells have a central role in SLE pathogenesis, being precursors of plasma cells production autoantibodies, precipitating inflammation by producing cytokines, activation T-cells by presentation of self-antigens, and regulating T-cells activity via co-stimulatory molecules. Although the clinical trials of RTX in SLE had controversial results, RTX seems to be a valuable option as an off-label drug for refractory patients.

Relevance of telomere/telomerase system impairment in early stage chronic lymphocytic leukemia

Several studies have proposed telomere length and telomerase activity as prognostic factors in chronic lymphocytic leukemia (CLL), whereas information addressing the role of telomere-associated genes is limited. We measured relative telomere length (RTL) and TERT expression levels in purified peripheral CD19(+) B-cells from seven healthy donors and 77 untreated CLLs in early stage disease (Binet A). Data were correlated with the major biological and cytogenetic markers, global DNA methylation (Alu and LINE-1), and clinical outcome. The expression profiles of telomere-associated genes were also investigated. RTL was decreased in CLLs as compared with controls (P < 0.001); within CLL, a progressive and significant RTL shortening was observed in patients from 13q- through +12, 11q-, and 17p- alterations; short telomeres were significantly associated with unmutated IGHV configuration and global DNA hypomethylation. Decreased RTL was associated with a shorter time to first treatment. A significant upregulation of POT1, TRF1, RAP1, MRE11A, RAD50, and RPA1 transcript levels was observed in CLLs compared with controls. Our study suggests that impairment of telomere/telomerase system represents an early event in CLL pathogenesis. Moreover, the correlation between telomere shortening and global DNA hypomethylation supports the involvement of DNA hypomethylation to increase chromosome instability. © 2014 Wiley Periodicals, Inc.

Increased Soluble CD154 (CD40 Ligand) Levels in Xenograft Recipients Correlate With the Development of De Novo Anti-Pig IgG Antibodies

De novo anti-pig antibodies are associated with acute humoral xenograft rejection. We explored the relative efficacy of CD40/CD154-pathway blockade versus CD28/B7-pathway blockade in the prevention of de novo anti-pig IgG antibodies in xenograft recipients. After α1,3-galactosyltransferase gene-knockout pig artery patch xenotransplantation, recipient baboons received no immunosuppression (IS; n=3), or anti-CD154mAb-based (n=5) or CTLA4-Ig-based (n=5) IS. CD4 T-cell and CD20 B-cell numbers in blood were determined. Serum anti-pig IgG antibodies and serum soluble (s)CD154 levels were measured. In lymph nodes, germinal center formation was examined and numbers of proliferating cells were evaluated by Ki-67 staining. After transplantation, with no IS, CD4 T-cell and CD20 B-cell numbers were increased, but were reduced by IS.In lymph nodes, with no IS, there was enhanced germinal center formation, which was significantly reduced by anti-CD154mAb-based (P<0.01) or CTLA4-Ig-based (P<0.01) IS. With no IS, there was strong expression of Ki-67-positive cells in lymph nodes, indicating extensive cellular proliferation. Ki-67-positive cells were significantly reduced by anti-CD154mAb-based (P<0.05) but not by CTLA4-Ig-based IS. High mean levels of sCD154 were detected with no IS (3324 pg/mL), in comparison to naive control baboons (214 pg/mL). With anti-CD154mAb-based IS, sCD154 was reduced to less than 1 pg/mL and with CTLA4-Ig-based IS to 65 pg/mL. There was significant positive correlation between sCD154 and anti-pig IgG levels (P<0.01). In xenograft recipients, anti-CD154mAb may reduce class-switching of anti-pig antibodies by binding both T-cell surface CD154 and circulating sCD154, thus preventing subsequent stimulation of B cells and activation of lymphoid follicles in secondary lymphoid tissues.

Forkhead box P3‐positive regulatory T‐cells and interleukin 17‐positive T‐helper 17 cells in chronic inflammatory periodontal disease

The role of two recently identified and closely related T-helper cell subsets - regulatory T-cells [Tregs; forkhead box P3-positive (FOXP3(+) )] and Th17 cells [interleukin-17-positive (IL-17(+) )] - in periodontal disease is yet to be determined. Tregs are essential in maintaining peripheral tolerance and regulating the immune response. Th17 cells play a critical role in several autoimmune diseases, inflammation and host defence. The aim of this study was to determine the presence of FOXP3(+) Tregs and IL-17(+) cells, and their possible spatial interaction, in diseased periodontal tissues. Twenty-nine archival tissues with nonspecific gingival inflammation were grouped based on the intensity (minimally or intensely inflamed) and nature (T-cell predominant or B- and plasma-cell predominant) of the inflammatory infiltrate. Using double-labelling immunohistochemistry, the concomitant presence of FOXP3(+) and IL-17(+) cells was determined and their spatial relationship was established. In addition, the proportions of FOXP3(+) and IL-17(+) cells were compared between the groups. Of the 29 gingival specimens investigated, 17 were intensely inflamed (≥1000 inflammatory cells per 0.12mm(2) ) and 12 were minimally inflamed (≤600 cells per 0.12mm(2) ). Based on the percentage of CD19(+) B-cells and plasma cells collectively and CD3(+) T-cells, gingival tissues were also grouped into B- and plasma-cell-predominant gingival tissues (n=21; 50.7% total B- and plasma cells vs. 19.1% T cells; p<0.001) and T-cell-predominant gingival tissues (n=8; 61.0% T-cells vs. 15.2% B- and plasma cells; p=0.007). More FOXP3(+) cells than IL-17(+) cells were observed in all archival gingival tissues examined. A trend towards an increased number of FOXP3(+) cells was observed for intensely inflamed gingival tissues (6.7%) and for B- and plasma-cell-predominant tissues (6.4%) compared with minimally inflamed gingival tissues (4.6%) and T-cell-predominant gingival tissues (4.5%). However, no statistically significant difference in the mean percentage of FOXP3(+) cells between the groups was observed. Interestingly, FOXP3(+) cells were significantly correlated with the B- and plasma-cell/T-cell ratio in B- and plasma-cell-predominant tissues (r=0.713, p<0.001). Overall, there were very few IL-17(+) cells (<1%). All IL-17(+) cells identified in this study had an ovoid/plasmacytoid morphology and were larger in size compared with adjacent inflammatory cells. IL-17(+) and FOXP3(+) cells were not adjacent to each other in any of the areas examined, suggesting that FOXP3(+) Tregs do not directly interact with IL-17(+) cells in diseased gingival tissues. IL-17(+) /FOXP3(+) cells were not detected in the tissues examined. These results show that FOXP3(+) cells are more prominent than IL-17(+) cells in periodontal disease processes, which may suggest a predominant role for FOXP3(+) cells in periodontal disease. Further studies are required to characterize these cells more precisely and to understand, in more detail, their roles in the pathophysiology of periodontal disease.

Human CD19 and CD40L deficiencies impair antibody selection and differentially affect somatic hypermutation

Individuals with genetic defects in CD40 ligand (CD40L) or B-cell antigen receptor coreceptor molecules CD19 and CD81 suffer from an antibody deficiency. Still, these patients carry low levels of memory B cells and serum antibodies. We sought to assess why the remaining memory B cells and antibodies in the blood of these patients do not provide functional immunity. We included CD19-deficient patients (n = 8), CD40L-deficient patients (n = 8), and healthy controls (n = 50) to perform detailed flow cytometry on blood B cells, molecular analysis of IgA and IgG transcripts, as well as functional analysis of B-cell activation. CD19-deficient and CD40L-deficient patients carried reduced numbers of all memory B-cell subsets except CD27(-)IgA(+) B cells. Their immunoglobulin heavy chain class-switched transcripts contained less somatic mutations and reduced usage of IgM-distal IgG2 and IgA2 subclasses. The selection strength of mutations for antigen binding was significantly lower than in controls, whereas selection to maintain superantigen binding was normal. Furthermore, the patients showed impaired selection against inherently autoreactive properties of their immunoglobulins. Somatic hypermutation analysis revealed decreased activation-induced cytidine deaminase and uracil-DNA glycosylase 2 activity in CD40L deficiency and increased uracil-DNA glycosylase 2 but decreased mismatch repair in CD19 deficiency. B-cell activation studies revealed that this was at least in part due to transcriptional regulation of DNA repair genes. This study on CD19 and CD40L deficiencies illustrates that both the B-cell antigen receptor and CD40 signaling pathways are required for the selection of immunoglobulin reactivity. Still, they differentially mediate DNA repair pathways during somatic hypermutation, thereby together shaping the human in vivo antigen-experienced B-cell repertoire.

Defective stromal remodeling and neutrophil extracellular traps in lymphoid tissues favor the transition from autoimmunity to lymphoma.

Altered expression of matricellular proteins can become pathogenic in the presence of persistent perturbations in tissue homeostasis. Here, we show that autoimmunity associated with Fas mutation was exacerbated and transitioned to lymphomagenesis in the absence of SPARC (secreted protein acidic rich in cysteine). The absence of SPARC resulted in defective collagen assembly, with uneven compartmentalization of lymphoid and myeloid populations within secondary lymphoid organs (SLO), and faulty delivery of inhibitory signals from the extracellular matrix. These conditions promoted aberrant interactions between neutrophil extracellular traps and CD5(+) B cells, which underwent malignant transformation due to defective apoptosis under the pressure of neutrophil-derived trophic factors and NF-κB activation. Furthermore, this model of defective stromal remodeling during lymphomagenesis correlates with human lymphomas arising in a SPARC-defective environment, which is prototypical of CD5(+) B-cell chronic lymphocytic leukemia (CLL).

A Case of Rituximab Therapy in Diffuse Alveolar Hemorrhage of Systemic Lupus Erythematosus Refractory to Steroid Pulse Therapy

Rituximab is a chimeric murine-human monoclonal antibody that is directed against the specific B-cell CD20 antigen, which has recently been successfully used in active or refractory systemic lupus erythematosus (SLE) manifestations, such as nephritis, thrombocytopenia, and vasculitis. We report a case of a 25-year-old woman diagnosed with diffuse alveolar hemorrhage of SLE refractory to steroid pulse therapy. The patient was treated successfully with rituximab as a part of the immunosuppressive regimen.

Application of a Modified Immunomagnetic Positive Selection Method for Isolation of Human CD34+ Stem/Progenitor from Cord Blood

Umbilical cord blood (UCB) and isolated umbilical cord blood stem cells (UCBSCs) have become an alternative source of hematopoietic progenitor cells for transplantation. The aim of this study was to test the effectiveness of some modifications of human hematopoietic stem cells isolation protocols with the intention of improving the output and viability of CD34+ cells and progenitor subpopulations progeny that can be obtained from a sample of human umbilical cord blood. By that, we contribute to current studies on the human hematopoietic stem cells (HSCs) in order to bank UCB units suitable for basic research of very long- term hematopoietic as well as for transplantation. Cord blood samples were transformed to buffy coat prior to the isolation of HSCs which was performed by two steps involving CD34 pre-enrichment using human cord blood CD34 positive selection kit and an Immunomagnetic cell separation, targeting CD34 surface antigen. CD34+ cells were immunophenotyped by four-color fluorescence, using a large panel of monoclonal antibodies (CD34/PE, CD45/FITC, CD38/APC, CD33/Per-Cy, HLA-DR/PE, CD117/APC, CD123/Per-Cy, CD105-FITC, CD56/ PE, CD14/Per-Cy, CD19/Per-Cy and CD3/APC) recognizing different lineage or activation antigens. Our results showed that the percentage of CD34+ cells in whole human cord blood samples was 0.02% of total cells. After isolation by two-step, combining CD34 pre-enrichment and Immunomagnetic isolation, the frequency of CD34+ stem cells represented 0.65% among total MNCs and 83.53% among total isolated cells. This isolation leaded to a purity of over 95% and viability of 98.60%. In addition, we found that the percentage of CD34+ cells which are CD45+ was 83.53%, whereas CD34+CD38- cells comprised 21.70%. About 70.85% of isolated CD34+ cells were characterized by the absence of human leukocyte antigen-DR (HLA-DR). Concerning the CD117, CD33, CD123 and CD105 antigens which characterize true stem cells, we found a high expression percentage among isolated HUCB CD34+ cells (81.26%, 57.14% 47.45%, 58.52% for CD117, CD33, CD123 and CD105, respectively), while a very small number displayed markers of advanced myeloid commitment, such as CD14 (Myeloid lineage, 0.7%) and CD56 (NK-cell lineage, 4.48%), or those of lymphoid differentiation: CD3 (T-cell lineage, 5.22%), and CD19 (B-cell lineage, 1.76%). After testing 12 samples of cord blood using modified positive magnetic isolation technique, no variations in subpopulations were observed from sample to sample. We conclude that our modified technique enabled us to obtain an important proportion of primitive hematopoietic progenitors, as suggested by the absence of HLA-DR and CD38, as well as the presence of CD117, CD33, CD123, and CD105 on their surface. These cells are recognized as having long term reconstitution capacity within the human CD34+cell population.

Treatment strategy for reducing the risk of rituximab-induced cytokine release syndrome in patients with intravascular large B-cell lymphoma: a case report and review of the literature

IntroductionIntravascular large B-cell lymphoma is a rare aggressive disseminated disease characterized by the presence of lymphoma cells in small vessels without lymphadenopathy. Rituximab, a novel monoclonal antibody against the CD20 B-cell antigen, has been reported to be effective in treating intravascular large B-cell lymphoma. However, adverse events have been reported in association with rituximab infusion.Case presentationWe report the case of a 54-year-old Japanese man diagnosed with Asian variant intravascular large B-cell lymphoma who died within five hours of the initiation of a first course of chemotherapy including rituximab. Autopsy results suggested that the patient died of severe systemic inflammatory response syndrome. A literature review revealed that rituximab administered during the second course of chemotherapy (instead of during the first course) appears to reduce the incidence of infusion reactions (from 48% to 15%) without altering the frequency of complete remission outcomes.ConclusionsOur data indicate that the incidence of adverse reactions to rituximab can be markedly decreased if the tumor load is first reduced with an initial course of chemotherapy excluding rituximab. Future prospective studies of the timing of rituximab administration are warranted.

Subcutaneous versus Intravenous Administration of Rituximab: Pharmacokinetics, CD20 Target Coverage and B-Cell Depletion in Cynomolgus Monkeys

The CD20-specific monoclonal antibody rituximab (MabThera®, Rituxan®) is widely used as the backbone of treatment for patients with hematologic disorders. Intravenous administration of rituximab is associated with infusion times of 4–6 hours, and can be associated with infusion-related reactions. Subcutaneous administration of rituximab may reduce this and facilitate administration without infusion-related reactions. We sought to determine the feasibility of achieving equivalent efficacy (measured by endogenous B-cell depletion) and long-term durability of CD20 target coverage for subcutaneously administered rituximab compared with intravenous dosing. In these preclinical studies, male cynomolgus monkeys were treated with either intravenous rituximab or novel subcutaneous formulation of rituximab containing human recombinant DNA-derived hyaluronidase enzyme. Peripheral blood samples were analyzed for serum rituximab concentrations, peripheral B-cell depletion, and CD20 target coverage, including subset analysis according to CD21+ status. Distal lymph node B-cell depletion and CD20 target coverage were also measured. Initial peak serum concentrations of rituximab were significantly higher following intravenous administration than subcutaneous. However, the mean serum rituximab trough concentrations were comparable at 2 and 7 days post-first dose and 9 and 14 days post-second dose. Efficacy of B-cell depletion in both peripheral blood and distal lymph nodes was comparable for both methods. In lymph nodes, 9 days after the second dose with subcutaneous and intravenous rituximab, B-cell levels were decreased by 57% and 42% respectively. Similarly, levels of peripheral blood B cells were depleted by >94% for both subcutaneous and intravenous dosing at all time points. Long-term recovery of free unbound surface CD20 levels was similar, and the duration of B-cell depletion was equally sustained over 2 months for both methods. These results demonstrate that, despite initial peak serum drug level differences, subcutaneous rituximab has similar durability, pharmacodynamics, and efficacy compared with intravenous rituximab.

TRAF6 is a critical regulator of LMP1 functionsin vivo

EBV-encoded latent membrane protein 1 (LMP1) is critical for EBV-driven B-cell transformation and most EBV-associated malignancies and is also implicated in exacerbation of autoimmunity. LMP1 functionally mimics the TNFR superfamily member CD40, but LMP1-induced signals and downstream B-cell functions are amplified and sustained compared with those mediated by CD40. CD40 and LMP1 both depend upon TNFR-associated factor (TRAF) adaptor molecules to mediate signaling but use them differently. LMP1 is dependent upon TRAFs 3 and 5 to deliver B-cell activation signals, while CD40 predominantly uses TRAFs 2 and 6 for this purpose. Both LMP1 and CD40 functions in B cells require TRAF6, which physically associates with both receptors but via different binding sites. In B-cell CD40 signaling, TRAF6 is required for a particular subset of CD40-dependent immune functions in vivo. Inasmuch as CD40 and LMP1 use other TRAFs differentially, we predicted that TRAF6 is critical for a specific subset of LMP1 functions in vivo and that this subset will be overlapping but distinct from the TRAF6-requiring functions of CD40. This study tests this prediction using a B-cell-specific TRAF6-deficient mouse model. We found that B-cell TRAF6 is important for LMP1-mediated antibody and autoantibody production in mice, as well as germinal center formation, but not the secondary lymphoid organ enlargement that results from LMP1 transgenic expression. Results highlight differential TRAF6 requirements for specific B-cell functions by LMP1 versus CD40. These differences may make important contributions to the contrasts between normally regulated CD40 versus pathogenic LMP1-mediated signals.

Intraocular and periocular lymphoma in dogs and cats: a retrospective review of 21 cases (2001–2012)

To immunologically phenotype and histologically classify canine and feline intraocular and periocular lymphomas. The databases of four veterinary medical diagnostic laboratories were searched to identify cases of intraocular or periocular lymphoma in dogs and cats between 2001 and 2012. Hematoxylin and eosin (H&E) stained slides were reviewed for confirmation and classification of lymphoma, and immunohistochemistry for CD3 (T-cell marker) and CD79a and/or CD20 (B-cell markers) was examined to determine the lineage of the neoplastic lymphocytes. Six canine and 15 feline cases of ocular lymphoma were identified. In the canine cases, there were three intraocular and three periocular lymphomas where two intraocular and one periocular lymphomas were B-cell, one of each intraocular and periocular lymphomas were T-cell and one periocular lymphoma was nonreactive with CD3, CD79a or CD20. In the feline cases, there were six intraocular and nine periocular lymphomas where five intraocular and six periocular lymphomas were B-cell, and one intraocular and three periocular lymphomas were T-cell. Only one canine case had concurrent generalized lymphadenopathy, only one canine conjunctival lymphoma had simultaneous cutaneous lymphoma, and only one feline case had bilateral ocular involvement when they were diagnosed. Canine and feline intraocular and periocular lymphomas are often of B-cell phenotype. Although in general terms lymphoma is not considered a primary tumor when it occurs in or adjacent to the globe, these tumors frequently first become evident in the globe and/or periocular area. An accurate early diagnostic approach is crucial for the patient's quality of life because B-cell lymphomas are generally more amenable to chemotherapy than T-cell lymphomas.

Recent Advances in the Understanding of the Pathophysiology of Preeclampsia

Preeclampsia, a pregnancy specific disorder, is typically defined as new-onset hypertension presenting after the 20th week of gestation with proteinuria. The overall prevalence in the United States is 3% to 8% with higher incidence in specific ethnic subpopulations, notably blacks. Preeclampsia is a major source of maternal and neonatal morbidity and mortality. Moreover, women who endure preeclampsia are at greater risk of cardiovascular diseases later in life. Studies published in Hypertension and other journals during the last few years have provided new insights not only into potential mechanisms underlying the pathophysiology of preeclampsia but also into the identification of potential biomarkers for the early diagnosis of preeclampsia. Although numerous factors have been implicated in the pathophysiology of preeclampsia, the main focus of this Recent Advances article is to review recent studies that link placental ischemia, endothelial and vascular dysfunction, and hypertension in preeclampsia. Despite intense research into the identification of molecular markers of preeclampsia, a reliable and accurate marker for the early diagnosis of preeclampsia remains elusive. A number of recent articles have suggested markers that could prove useful in the diagnosis of the disorder. With the growing interest in autoimmunity in preeclampsia, several studies have looked at immune factors in the maternal circulation as possible biomarkers. For instance, Siddiqui et al1 found widespread (≈95%) presence of agonistic autoantibodies to the angiotensin type-1 receptor (AT1-AA). Additionally, the levels of these autoantibodies correlated well with the degree of disease severity, suggesting potential use in diagnosis. In a related study, Jensen et al2 found that CD19(+)CD5(+) B-cell populations, a potential source for the AT1-AA, are significantly elevated in the maternal circulation of patients with preeclampsia during late gestation when compared with normal-pregnant controls at the same gestational stage. One of the most active areas of research in preeclampsia is angiogenic …

Expression pattern of tumour-associated antigens in hepatocellular carcinoma: association with immune infiltration and disease progression

Background:The distinct expression pattern of tumour-associated antigens (TAAs) might be a critical reason for the inefficacy of immunity-based treatments and heterogeneous postsurgical recovery in patients with solid tumours, including hepatocellular carcinoma (HCC). However, little is known about the clinical value of the coexpression patterns of multiple TAAs.Methods:We determined the expression of multiple TAAs with identified immunogenicity (GPC3, AFP, SSX-2, NY-ESO-1, EpCAM, midkine) and the density of tumour-infiltrating immune cells by immunohistochemistry in a panel of 362 primary HCC patients. We evaluated the association between the TAAs, immune cell infiltration, clinicopathological parameters, and prognosis.Results:Patients who coexpressed more TAAs had better prognosis (P<0.00001, overall survival). The integrated pattern of TAA was associated with good differentiation and small tumour size, and with more CD57+ natural killer and CD20+ B-cell infiltration (P<0.05). Multivariate Cox proportional hazards analysis identified the TAA index as an independent prognostic indicator (hazard ratio 0.625; 95% confidence interval 0.467–0.837; P=0.002), and could further predict patient prognosis in collaboration with local immune infiltration.Conclusion:Our results could provide new evidence for the improvement of prognostic molecular signatures in HCC, and a novel rationale for patient enrolment in future immunotherapeutic trials and/or clinical treatments.

Therapeutic Targeting of B Cells and T Cells in Autoimmune Diabetes

Insulin-dependent type 1 diabetes (T1D) is attributable to the destruction of pancreatic β-cells by autoreactive T lymphocytes (T cells). Antibodies to various β-cell autoantigens also are detected in T1D that are not pathogenic but represent excellent markers of β-cell destruction and are widely used to identify high-risk individuals (1,2). This by no means excludes a major role for B lymphocytes (B cells) in the development and progression of T1D. Serreze et al. (3) first showed that disease-prone nonobese diabetic (NOD) mice lacking B cells were completely protected from disease, a finding explained by the capacity of B cells to present autoantigens (4). Furthermore, B cells are essential for “antigen/epitope spreading,” a central mechanism underlying the chronicity of autoimmunity that is the progressive diversification of the autoimmune response from one epitope to another, expressed by the same or by a distinct autoantigen (i.e., intramolecular spreading compared with intermolecular spreading) (5,6). All this explains the therapeutic potential of monoclonal antibodies targeting B cells or their growth factors to halt progression of T1D in NOD mice (7–10). Thus, depleting antibodies directed to the CD20 B-cell antigen efficiently prevented disease when administered to prediabetic NOD mice and, although in a low proportion of animals, also temporarily reversed T1D once hyperglycemia was established (8). Importantly, a randomized placebo-controlled phase II study conducted established that in recent-onset T1D patients a single course of rituximab, a humanized CD20 monoclonal antibody, significantly preserved endogenous insulin secretion as compared with placebo (11). However, the effect was transient and the therapeutic benefit waned as B-cell numbers recovered, implying that “operational” immune tolerance, intended as the specific inhibition of the autoimmune response in absence of chronic …

Successful treatment of central nervous system PTLD with rituximab and cranial radiotherapy

Primary central nervous system (PCNS) post-transplant lymphoproliferative disorder (PTLD) is a rare complication of solid organ transplantation and is typically an Epstein-Barr virus (EBV)-induced B-cell CD20+ lymphoma. The modalities of treatment include reduction in immunosuppression, cranial radiotherapy (CRT), intravenous and intrathecal rituximab when CD20 is expressed on B-lymphocytes and PTLD cells, and chemotherapy. We report the successful treatment of EBV-driven PCNS PTLD by reduction in immunosuppression (RI), CRT, and intravenous rituximab. Our patient was an 11-year-old boy with a living-related renal transplant for end-stage renal failure (ESRF) secondary to posterior urethral valves (PUV) and bilateral renal dysplasia (BRD) and on triple immunosuppression with prednisolone, tacrolimus, and azathioprine who had a rising EBV load, which was managed with reduction in tacrolimus dose, withdrawal of azathioprine, and introduction of mycophenolate mofetil (MMF). The patient presented 7 years post-transplant with a seizure and abnormal neurology secondary to polymorphous hyperplastic lesions in the brain, which responded to rituximab and CRT.

THU0107 CCL19, a chemokine involved in B-cell trafficking, is related to the decrease of blood memory B-cells and predicts the clinical response to rituximab in rheumatoid arthritis: Results from the smart study

BackgroundIn rheumatoid arthritis (RA), the decrease of peripheral blood memory B-cell may be explained by their migration into the synovium and predicts the response to rituximab (RTX), delineating thus a...

B-cell linker protein expression contributes to controlling allergic and autoimmune diseases by mediating IL-10 production in regulatory B cells

Regulatory B cells that exhibit the cell-surface CD1d(hi)CD5(+) phenotype and produce IL-10 are termed B10 cells. Although B10 cells exert potent suppressive functions in patients with various allergic and autoimmunity disorders, the precise signaling mechanisms required for B10 cell functions remain unknown. B-cell linker protein (BLNK) is an essential component of the B-cell antigen receptor signaling pathway and is required for optimal B-cell development. We sought to elucidate the signaling pathways that are responsible for IL-10 production in B10 cells and in vivo mechanisms of how impaired B10 cell functions influence allergic and autoimmune responses. For in vitro assays, splenic CD1d(hi)CD5(+) B cells from BLNK-deficient (BLNK(-/-)) mice were analyzed for intracellular signaling pathways and cytokine production. Contact hypersensitivity (CHS) and experimental autoimmune encephalomyelitis were examined by using BLNK(-/-) mice. Although the CD1d(hi)CD5(+) B-cell population was present in BLNK(-/-) mice, IL-10 production was impaired both in vitro and in vivo. BLNK(-/-) mice had exaggerated CHS and experimental autoimmune encephalomyelitis responses, which were normalized by adoptive transfer of splenic CD1d(hi)CD5(+) B cells from wild-type mice. In mice with CHS, BLNK(-/-) mice exhibited decreased B-cell and regulatory T-cell percentages and increased CD8(+) T-cell percentages in the skin and lymph nodes. In vitro BLNK was required for LPS-induced signal transducer and activator of transcription 3 phosphorylation in CD1d(hi)CD5(+) B cells. Finally, secreted IL-10 leads to autocrine expansion of IL-10-producing B cells. BLNK serves as a critical signaling component for B10 cell function by mediating IL-10 production.

Ulcère de jambe lié à une cryoglobulinémie de type 1 révélant un lymphome B « incipiens »

Skin lesions are frequent in monoclonal cryoglobulinaemia and may be the first sign of B-cell lymphoma, especially multiple myeloma, Waldenström's macroglobulinaemia and B-cell chronic lymphocytic leukaemia. A 74-year-old woman with no prior medical history presented with necrotic leg ulcer. Skin biopsy showed dermal angiomatosis with numerous PAS+ thromboses, associated with monoclonal intravascular deposits of IgM kappa, indicating monoclonal cryoglobulin, which was confirmed by laboratory tests. Subsequent blood immunophenotyping revealed an inconspicuous circulating monoclonal CD5(+) B-cell population and small B-cell clusters in the bone marrow, while the B-cell count was normal and no lymphadenopathy or splenomegaly were present. Overall, these findings indicated a small B-cell lymphoma, classed as non-MALT marginal zone lymphoma on the WHO classification, at a very early stage of development. The patient was first treated by cyclophosphamide and oral steroids without success. Subsequent administration of six cycles of rituximab, cyclophosphamide, vincristine and prednisone (RCVP) led to remission of her leg ulcer, cryoglobulinaemia and lymphoma. Skin biopsies of necrotic ulcers should undergo routine screening for intravascular deposits of type 1 cryoglobulin. Leg ulcers due to monoclonal cryoglobulinaemia may reveal incipient marginal zone B-cell lymphoma at the stage of circulating monoclonal lymphocytosis.