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Naive B cells co-express two BCR isotypes, IgM and IgD, with identical antigen-binding domains but distinct constant regions. IgM but not IgD is downregulated on autoreactive B cells. Because these isotypes are presumed to be redundant, it is unknown how this could impose tolerance. We introduced the Nur77-eGFP reporter of BCR signaling into mice that express each BCR isotype alone. Despite signaling strongly in vitro, IgD is less sensitive than IgM to endogenous antigen in vivo and developmental fate decisions are skewed accordingly. IgD-only Lyn -/- B cells cannot generate autoantibodies and short-lived plasma cells (SLPCs) in vivo, a fate thought to be driven by intense BCR signaling induced by endogenous antigens. Similarly, IgD-only B cells generate normal germinal center, but impaired IgG1 + SLPC responses to T-dependent immunization. We propose a role for IgD in maintaining the quiescence of autoreactive B cells and restricting their differentiation into autoantibody secreting cells., Competing Interests: MN, JM, AS, LG, FB, JZ No competing interests declared, (© 2018, Noviski et al.)

Background: Haemophilus influenzae (Hi) causes respiratory infections and pathogenesis of this microbe begins in the human nasopharynx (NP). The objective of this study was to assess the correlation of NP colonization-induced serum antibody levels to Hi protein D with risk of acute otitis media (AOM) in children <2 yr., Methods: 455 sera from 213 children (age 6-24 months old) were collected when they were colonized with Hi and when the children developed AOM. Presence of Hi during AOM was confirmed by culture of middle ear fluid. Quantitative ELISA was used to determine serum IgG against protein D antigen., Results: Asymptomatic Hi NP colonization reduced the risk of future AOM infections. Higher serum IgG titers against Hi protein D were correlated with reduced future AOM risk., Conclusion: Colonization by Hi reduces future AOM risk. Higher antibody levels against protein D correlates with lower risk of AOM caused by Hi., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

We investigated the correlation between the increased proportion of peripheral B cell subsets and clinical and immunological features in primary Sjögren's syndrome (pSS). We found that the proportion of CD19 + B cells was significantly increased in pSS as compared with HC and was correlated with serum IgG levels. Moreover, in vitro IgG production by CD19 + B cells was significantly increased in pSS and was positively and significantly correlated with serum IgG levels. FACS analysis revealed that the proportions of peripherally CD38 high IgD + B cells and CD38 high IgD - B cells were significantly increased in pSS. In addition, the proportion of CD38 high IgD + B cells positively correlated with ESSDAI scores and serum levels of IgG, anti-Ro/SSA and anti-La/SSB antibodies while that of CD38 high IgD - B cells showed no correlation with these parameters. Our data suggest that increased proportion of CD38 high IgD + B cells in pSS is involved in IgG overproduction including autoantibodies, and correlates with disease progression., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to assess the therapeutic effects of biological DMARDs (bDMARDs) on the diversity of immune cell phenotypes in peripheral blood of patients with RA., Methods: Peripheral immune cell phenotypes were determined in 108 RA patients who were non-responsive to conventional DMARDs and 33 healthy control subjects by eight-colour flow cytometry. We also examined the correlation between the phenotypes and clinical findings and assessed the effects of 24-week treatment with bDMARDs., Results: The proportions of T follicular helper (Tfh) cells, IgD- CD27- double negative B cells and plasmacytoid dendritic cells (pDCs) were higher in patients with active RA than in healthy control. The percentages of memory T cells, Th17 and Tfh cells correlated with autoantibody titres, whereas that of plasmablasts correlated with disease activity scores. Treatment with TNF inhibitors reduced the proportion of pDCs, while tocilizumab reduced the proportion of double-negative B cells but increased naïve and activated Treg cells. Abatacept treatment resulted in marked decrease in the proportion of activated Tfh but slightly reduced Th17 and Treg cells. The proportion of Tfh cells was an independent and significant predictor of the response to abatacept therapy., Conclusion: Molecular targeted therapies induced different changes in different immune cell phenotypes. Among the phenotypes, Tfh cells seem a potential target for abatacept. Immunophenotypic analysis might be useful for prediction of the response to bDMARDs., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com)

Objective: To elucidate the diversity of systemic lupus erythematosus (SLE) based on immunophenotyping., Methods: Peripheral blood mononuclear cells were obtained from 143 SLE patients and 49 healthy individuals. Circulating B, T, and dendritic cells were defined using flow cytometric analysis as recommended by the Human Immunology Project Consortium. Based on these results, immunophenotypes were distinguished by principal components analysis (PCA), and cluster analysis was used to classify SLE patients into subgroups., Results: The proportions of Treg and follicular helper T (Tfh) cells were higher in SLE patients than in healthy controls, whereas Th1 and Th17 cell proportions did not differ. Proportions of class-switched memory B cells and IgD-CD27- B cells were increased in SLE patients as well. The largest difference compared to the control group was observed in the proportion of plasmablasts, which was higher in SLE patients and correlated with disease activity as assessed with the British Isles Lupus Assessment Group index. PCA indicated that the immunophenotype of SLE patients consisted of abnormalities of the T and B cell axes. Cluster analysis showed that the SLE patients could be stratified into 3 subgroups (with high proportions of plasmablasts in all groups): patients who did not show the characteristic features (T cell-independent group), patients with a high percentage of Tfh cells (Tfh-dominant group), and patients with a high percentage of memory Treg cells (Treg-dominant group). The percentage of patients whose SLE was resistant to treatment was highest among the Tfh-dominant group., Conclusion: Our study indicates that patients with active SLE can be divided into 3 subgroups based on T cell heterogeneity. Further immunophenotyping studies should help elucidate the pathogenesis of SLE and provide important information for the development of new therapies., (© 2017, American College of Rheumatology.)

Chronic idiopathic neutropenia (CIN) is a granulocytic disorder associated with presence of activated, myelosuppressive T-lymphocytes. In the present study we have evaluated constituents of humoral immunity in CIN patients (n=48) compared to healthy controls (n=52). CIN patients displayed lower serum IgG levels due to a reduction in IgG1, IgG3, IgG4 but not IgG2, lower IgA and increased IgM levels compared to controls. The proportion of CD19 + cells did not differ between patients and controls; however the proportion of the naïve IgD + /CD27 - B-cells was increased and the proportion of class-switched memory IgD - /CD27 + B-cells was decreased in the patients. The percentage of CD40 + B-cells did not differ between patients and controls and no aberrations in the CD40-meadiated signal transduction pathway or in CD40-gene polymorphisms were identified. These data provide further evidence that immune disturbances are associated with the pathophysiology of CIN and point out for the first time the implication of the B-cell system., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Caveolin-1 (Cav1) regulates the nanoscale organization and compartmentalization of the plasma membrane. Here we found that Cav1 controlled the distribution of nanoclusters of isotype-specific B cell antigen receptors (BCRs) on the surface of B cells. In mature B cells stimulated with antigen, the immunoglobulin M BCR (IgM-BCR) gained access to lipid domains enriched for GM1 glycolipids, by a process that was dependent on the phosphorylation of Cav1 by the Src family of kinases. Antigen-induced reorganization of nanoclusters of IgM-BCRs and IgD-BCRs regulated BCR signaling in vivo. In immature Cav1-deficient B cells, altered nanoscale organization of IgM-BCRs resulted in a failure of receptor editing and a skewed repertoire of B cells expressing immunoglobulin-μ heavy chains with hallmarks of poly- and auto-reactivity, which ultimately led to autoimmunity in mice. Thus, Cav1 emerges as a cell-intrinsic regulator that prevents B cell-induced autoimmunity by means of its role in plasma-membrane organization.

B cells play a crucial role in the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE). However, the relevance of the metabolic pathway in the differentiation of human B cell subsets remains unknown. In this article, we show that the combination of CpG/TLR9 and IFN-α markedly induced the differentiation of CD27 + IgD + unswitched memory B cells into CD27 hi CD38 hi plasmablasts. The response was accompanied by mammalian target of rapamycin complex 1 (mTORC1) activation and increased lactate production, indicating a shift to glycolysis. However, CpG alone induced the differentiation of unswitched memory B cells into CD27 - IgD - memory B cells with high cytokine production, but such differentiation was suppressed by IFN-α. AMP-activated protein kinase activation enhanced the differentiation to CD27 - IgD - B cells, but it attenuated mTORC1 activation and differentiation into plasmablasts. High mTORC1 activation was noted in CD19 + B cells of patients with SLE and correlated with plasmablast differentiation and disease activity. Taken together, differential metabolic reprogramming commits the differentiation of human unswitched memory B cells into plasmablasts (the combination of CpG and IFN-α amplifies mTORC1-glycolysis pathways) or CD27 - IgD - memory B cells (CpG alone amplifies the AMP-activated protein kinase pathway). The former metabolic pathway may play a pivotal role in SLE., (Copyright © 2017 by The American Association of Immunologists, Inc.)

Introduction: Protein D-containing vaccines may decrease acute otitis media (AOM) burden and nasopharyngeal carriage of non-typeable Haemophilus influenzae (NTHi). Protein D-containing pneumococcal conjugate vaccine PHiD-CV (Synflorix, GSK Vaccines) elicits robust immune responses against protein D. However, the phase III Clinical Otitis Media and PneumoniA Study (COMPAS), assessing PHiD-CV efficacy against various pneumococcal diseases, was not powered to demonstrate efficacy against NTHi; only trends of protective efficacy against NTHi AOM in children were shown. Areas covered: This review aims to consider all evidence available to date from pre-clinical and clinical phase III studies together with further evidence emerging from post-marketing studies since PHiD-CV has been introduced into routine clinical practice worldwide, to better describe the clinical utility of protein D in preventing AOM due to NTHi and its impact on NTHi nasopharyngeal carriage. Expert commentary: Protein D is an effective carrier protein in conjugate vaccines and evidence gathered from pre-clinical, clinical and observational studies suggest that it also elicits immune response that can help to reduce the burden of AOM due to NTHi. There remains a need to develop improved vaccines for prevention of NTHi disease, which could be achieved by combining protein D with other antigens.

We previously reported 10-valent pneumococcal non-typeable Haemophilus influenzae (NTHi) protein D conjugate vaccine (PHiD-CV) efficacy in a double-blind randomized trial (ClinicalTrials.gov: NCT00466947) against various diseases, including acute otitis media (AOM). Here, we provide further analyses. In the Panamanian subset, 7,359 children were randomized (1:1) to receive PHiD-CV or control vaccine at age 2/4/6 and 15-18 months. Of these, 2,000 had nasopharyngeal swabs collected. AOM cases were captured when parents sought medical attention for children with AOM symptoms; surveillance was enhanced approximately 2 y into the study through regular telephone calls or home visits by study personnel, who advised parents to visit the clinic if their child had AOM symptoms. Mean follow-up was 31.4 months. Clinical AOM (C-AOM) cases were assessed by physicians and confirmed by otorhinolaryngologists. Middle ear fluid samples, taken from children with C-AOM after specific informed consent, and nasopharyngeal samples were cultured for pathogen identification. For 7,359 children, 2,574 suspected AOM cases were assessed by a primary healthcare physician; 649 cases were C-AOM cases as per protocol definition. From the 503 MEF samples collected, 158 resulted in a positive culture. In the intent-to-treat cohort (7,214 children), PHiD-CV showed VE against first C-AOM (24.0% [95% CI: 8.7, 36.7]) and bacterial (B-AOM) episodes (48.0% [20.3, 66.1]) in children <24 months, which declined thereafter with age. Pre-booster VE against C-AOM was 30.7% [12.9, 44.9]; post-booster, -6.7% [-36.4, 16.6]. PHiD-CV VE was 17.7% [-6.1, 36.2] against moderate and 32.7% [-20.5, 62.4] against severe C-AOM. VE against vaccine-serotype pneumococcal NPC was 31.2% [5.3, 50.3] 3 months post-booster, and 25.6% [12.7, 36.7] across all visits. NTHi colonization rates were low and no significant reduction was observed. PHiD-CV showed efficacy against C-AOM and B-AOM in children younger than 24 months, and reduced vaccine-serotype NPC.

Mature B cells coexpress both IgM and IgD B-cell antigen receptor (BCR) classes, which are organized on the cell surface in distinct protein islands. The specific role of the IgD-BCR is still enigmatic, but it is colocalized with several other receptors on the B-cell surface, including the coreceptor CD19. Here, we report that the chemokine receptor CXCR4 is also found in proximity to the IgD-BCR. Furthermore, B cells from IgD-deficient mice show defects in CXCL12-mediated CXCR4 signaling and B-cell migration, whereas B cells from IgM-deficient mice are normal in this respect. CXCR4 activation results in actin cytoskeleton remodeling and PI3K/Akt and Erk signaling in an IgD-BCR-dependent manner. The defects in CXCR4 signaling in IgD-deficient B cells can be overcome by anti-CD19 antibody stimulation that also increases CXCL12-mediated B-cell migration of normal B cells. These results show that the IgD-BCR, CD19, and CXCR4 are not only colocalized at nanometer distances but are also functionally connected, thus providing a unique paradigm of receptor signaling cross talk and function., Competing Interests: The authors declare no conflict of interest.

Background: Immunogenicity, safety and reactogenicity of the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) were evaluated in children with sickle cell disease (SCD), who are at increased risk for infections., Methods: In this phase III, open-label, single-center, controlled study in Burkina Faso (NCT01175083), children with SCD (S) or without SCD (NS) were assigned to 6 groups (N = 300): children 8-11 weeks of age (<6 months; <6S and <6NS groups) received 3 primary doses and a booster dose of PHiD-CV coadministered with routine childhood vaccines; children 7-11 months of age (7-11S and 7-11NS groups) received 2 primary doses and a booster dose of PHiD-CV; children 12-23 months of age (12-23S and 12-23NS groups) received 2 catch-up doses of PHiD-CV. Pneumococcal antibody responses were measured using 22F-inhibition enzyme-linked immunosorbent assay and functional opsonophagocytic activity. Responses to other antigens were measured by enzyme-linked immunosorbent assay. Adverse events were recorded., Results: One month postprimary vaccination, for each vaccine serotype ≥98% of infants in the <6S and <6NS groups had antibody concentrations ≥0.2 µg/mL, except for 6B (≥85%) and 23F (≥89%). Immune responses to PHiD-CV after age-appropriate vaccination in children <2 years did not appear influenced by SCD. All infants were seroprotected/seropositive for diphtheria, tetanus and Bordetella pertussis antigens postprimary and booster vaccination. Safety and reactogenicity profiles were similar in children with or without SCD., Conclusions: PHiD-CV was immunogenic with an acceptable safety profile in children with and without SCD starting vaccination at 8 weeks to 23 months of age.

Immunoglobulin D (IgD) is the least studied of immunoglobulin classes. This study sought to investigate the potential relationship between demographic, metabolic, lifestyle and immunological factors, and serum IgD concentrations in a general adult population. We measured serum IgD concentrations by means of a commercial turbidimetric assay in 413 individuals (median age, 55 years; 45% males), randomly selected from the adult population of a Spanish municipality. Serum IgD concentrations displayed considerable variation in the population, ranging from undetectable (<6.7 mg/l) to 878 mg/l. Serum IgD concentrations were undetectable in 78 cases (18.9%) and >100 mg/l in 39 cases (9.4%). Median IgD was 21.9 mg/l. Serum IgD concentrations were negatively associated with age and positively associated with smoking, after adjustment for potential confounders. Overweight individuals showed lower concentrations of IgD than did normal-weight individuals. Atopy (positivity of skin tests to aeroallergens) was not significantly associated with IgD concentrations, although non-symptomatic atopics showed higher IgD concentrations. No consistent association was observed between serum IgD concentrations and gender, metabolic syndrome, or alcohol consumption. No significant association was found between baseline IgD concentrations and development of either allergic or immune disease after a median 11.4 years of follow-up. In conclusion, serum IgD concentrations in adults show a wide variation in the population and may be influenced by common factors, particularly age and smoking habit. These factors should be taken into account when defining reference ranges for serum IgD concentrations., (© 2017 The Foundation for the Scandinavian Journal of Immunology.)

Secreted IgD concentration depends on the presence of microbiota., (Copyright © 2017, American Association for the Advancement of Science.)

Class-switch recombination (CSR) alters the Ig isotype to diversify antibody effector functions. IgD CSR is a rare event, and its regulation is poorly understood. We report that deficiency of 53BP1, a DNA damage-response protein, caused age-dependent overproduction of secreted IgD resulting from increased IgD CSR exclusively within B cells of mucosa-associated lymphoid tissues. IgD overproduction was dependent on activation-induced cytidine deaminase, hematopoietic MyD88 expression, and an intact microbiome, against which circulating IgD, but not IgM, was reactive. IgD CSR occurred via both alternative nonhomologous end-joining and homologous recombination pathways. Microbiota-dependent IgD CSR also was detected in nasal-associated lymphoid tissue of WT mice. These results identify a pathway, present in WT mice and hyperactivated in 53BP1-deficient mice, by which microbiota signal via Toll-like receptors to elicit IgD CSR.

Purpose: We report a 75-year-old woman with a history of multiple myeloma immunoglobulin D (IgD) variant, who presented with an epibulbar plasmacytoma masquerading as a subconjunctival hemorrhage., Methods: Magnetic resonance imaging of the brain and orbits with and without contrast was obtained and surgical biopsy of the subconjunctival lesion was performed; histopathology confirmed the diagnosis of plasmacytoma., Results: Subconjunctival biopsy revealed a plasma cell neoplasm infiltrate in the episcleral layer. The subconjunctival biopsy stained positive for CD138 and lambda-immunohistochemistry in the majority of plasma cells. Histologic findings were consistent with involvement by known IgD plasma cell myeloma where previous bone marrow biopsy demonstrated myeloma cells which stained monoclonally for IgD-lambda light chains., Conclusions: Although plasma cell neoplasms seldom present with ocular manifestations, it is crucial to recognize that these tumors may be associated with multiple myeloma. In patients with known multiple myeloma who present with subconjunctival hemorrhage, close follow-up is highly recommended, as this may be the initial presentation of an ocular plasmacytoma. Although a plasmacytoma is a rare subconjunctival lesion, it should not be immediately excluded from the differential diagnosis of such lesions.

The elderly have reduced humoral immunity, as manifested by increased susceptibility to infections and impaired vaccine responses. To investigate the effects of aging on B-cell receptor (BCR) repertoire evolution during an immunological challenge, we used a phylogenetic distance metric to analyze Ig heavy-chain transcript sequences in both young and elderly individuals before and after influenza vaccination. We determined that BCR repertoires become increasingly specialized over a span of decades, but less plastic. In 50% of the elderly individuals, a large space in the repertoire was occupied by a small number of recall lineages that did not decline during vaccine response and contained hypermutated IgD + B cells. Relative to their younger counterparts, older subjects demonstrated a contracted naive repertoire and diminished intralineage diversification, signifying a reduced substrate for mounting novel responses and decreased fine-tuning of BCR specificities by somatic hypermutation. Furthermore, a larger proportion of the repertoire exhibited premature stop codons in some elderly subjects, indicating that aging may negatively affect the ability of B cells to discriminate between functional and nonfunctional receptors. Finally, we observed a decreased incidence of radical mutations compared with conservative mutations in elderly subjects' vaccine responses, which suggests that accumulating original antigenic sin may be limiting the accessible space for paratope evolution. Our findings shed light on the complex interplay of environmental and gerontological factors affecting immune senescence, and provide direct molecular characterization of the effects of senescence on the immune repertoire., Competing Interests: Dr. Quake and Dr. Knight were coauthors on Biteen JS, et al. (2015) Tools for the microbiome: Nano and beyond. ACS Nano 10(1):6–37. This was a perspective and did not involve any active research collaboration.

Background: The mother's immune status can be achieved by genetic and breastfeeding impact descendants of the immune system. The study aimed to determine whether a mother's immune status and breastfeeding practices were related to development of bronchiolitis in her infant., Methods: The frequency of T, B and natural kill (NK) cells in patients' blood and their mothers' breast milk was determined using flow cytometry. The concentrations of serum and breast milk IgG and IgD in individual patients and healthy control were determined by enzyme-linked immunosorbent assay (ELISA). The relationships between immunocytes, immunoglobulin and respiratory score (RS) were analyzed by Spearman's rank correlation test., Results: The mothers of bronchiolitis patients had lower IgG concentrations in their breast milk when compared to the mothers of healthy children. There was no significant difference in the frequency of T cells, B cells, and NK cells in samples of breast milk. However, significant decreases of CD3+, CD8+ T cells, as well as significant increases of CD4+ T cells and CD19+ B cells were found in the serum of bronchiolitis infants. There were positive correlation relationships between RS and CD3+, CD4+ T cells, IgG and IgD concentrations., Conclusion: Our data suggested that the mothers of bronchiolitis patients had lower IgG concentration in their breast milk. The breast milk IgG might be absorbed by the breastfeeding infants, which could play important role in resistance of bronchiolitis.

Objectives: Behçet's disease (BD), an auto-inflammatory vasculitis with oro-genital ulcerations, skin lesions and uveitis, is regarded as T cell mediated. A successful trial with rituximab suggests an additive role for B cells in the pathogenesis. Therefore, we studied B cell abnormalities in BD patients and the effect of TNF-blocking therapy., Methods: B cells in blood (n = 36) and tissue (n = 6) of BD patients were analysed with flow cytometry and/or immunohistochemistry and compared with healthy controls (n = 22). BD current activity form (BDCAF) in relation to B cell somatic hypermutations (SHMs) and immunoglobulin class-switching were studied., Results: Thirty-six patients (17 males) were included, mean age 44 years, average disease duration 10 years and mean BDCAF 2.7. Blood B cell numbers were significantly lower in patients than in controls (P = 0.0061), mostly due to decreased CD27 + memory B cells expressing IgM (P = 0.0001), IgG (P = 0.0002) and IgA (P = 0.0038) B cell subsets. CD27 + IgA + B cells showed the highest magnitude of decrease in active disease, measured with BDCAF (P = 0.02). CD27 + IgM + IgD + B cells were impaired in replication history (P = 0.0133) and selection of SHM, whereas IgA + B cells carried elevated SHM levels (P = 0.04) and lower IgA2 subclass usage (P = 0.0004) than controls. Immunohistochemistry revealed B cells in tissue of active mucosal ulcers. In adalimumab-treated patients, blood B cells were similar to controls., Conclusion: We show significant deviations in the memory B cell compartment, related to disease activity and therapeutic efficacy. Pronounced molecular impairments were seen in the fast-responding IgM + -memory and the mucosal IgA + -memory B cells. Because of the demonstrated abundance of B cells in affected tissue, we hypothesize relocation of memory B cells to the site of inflammation could account for the deviations found in blood of BD patients. These peripheral B cells are easily accessible as a marker to monitor therapeutic efficacy., (© The Author 2016. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Phase III, open-label, single-center, controlled study in South Africa (ClinicalTrials.gov: NCT00829010) to evaluate immunogenicity, reactogenicity, and safety of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in human immunodeficiency virus (HIV)-infected (HIV+), HIV-exposed-uninfected (HEU), and HIV-unexposed-uninfected (HUU) children., Methods: Children stratified by HIV status received PHiD-CV primary vaccination (age 6/10/14 weeks; coadministered with routine childhood vaccines) and booster dose (age 9-10 months). Immune responses, assessed using enzyme-linked immunosorbent and functional assays, and safety were evaluated up to 14 months post-booster., Results: Of 83, 101, and 100 children enrolled in HIV+, HEU, and HUU groups, 70, 91, and 93 were included in according-to-protocol immunogenicity cohort. For each vaccine-serotype, percentages of children with antibody concentrations ≥0.2 μg/mL were ≥97% 1 month post-primary vaccination and ≥98.5% 1 month post-booster (except for 6B and 23F at both timepoints). Post-primary vaccination, functional antibody responses were lower in HIV+ children: for each vaccine-serotype, percentages of children with opsonophagocytic activity (OPA) titres ≥8 were ≥72%, ≥81%, and ≥79% for HIV+, HEU, and HUU children. Post-booster, ≥87% of children in each group had OPA titres ≥8. Reactogenicity was similar across groups. Thirty one (37%) HIV+, 25 (25%) HEU, and 20 (20%) HUU children reported ≥1 serious adverse event. Five HIV+ and 4 HEU children died. One death (sudden infant death syndrome; HEU group; 3 days post-dose 1) was considered potentially vaccine-related., Conclusion: PHiD-CV was immunogenic and well-tolerated in HIV+, HEU, and HUU children, and has the potential to provide substantial benefit irrespective of HIV infection status., Competing Interests: NF, JR-G, J-PY, MM, DB, and LS are employees of the GSK group of companies. JR-G, J-PY, MM, DB, and LS own shares of the GSK group of companies. Outside the submitted work, SAM declares his institution having received grants from Bill & Melinda Gates Foundation, the GSK group of companies, Novartis and Minervax. SAM has received consulting fees for advisory boards from the GSK group of companies, Medimmune, and Pfizer and payment for lectures including service on speakers bureaus from Sanofi Pasteur, the GSK group of companies, and Pfizer. SAM has also received payment from Medimmune for the development of educational presentations. All other authors declare no conflict of interest.

Introduction: Identifying ideal non typeable Haemophilus influenzae (NTHi) vaccine candidates has not been easy due to extensive sequence and antigenic variation among gene products interacting with the immune system. Protein D (PD) is a highly conserved 42 kDa surface lipoprotein available in all H. influenzae, including NTHi., Methodology: In this study, the gene encoding PD was cloned from H. influenzae and expressed in Escheriachia coli TOPO10 cell in pBAD vector. Arabinose was used to express recombinant protein. In order to purify the protein, Ni-NTA agarose was used to perform affinity chromatography. Purified PD and PD mixed with outer membrane vesicle (OMV) and alum adjuvant were used for subcutaneous immunization in BALB/c mice. After vaccination, IgG responses to PD-OMV, PD-alum, and PD alone were determined by enzyme-linked immunosorbent assay (ELISA)., Results: The recombinant PD containing His6 residues showed a molecular weight of 42 kDa. Anti-PD IgG was detected after first immunization in all groups of mice compared to the negative control group, and it increased after first vaccination, but results showed that the addition of OMV to PD led to a remarkable increase in IgG responses., Conclusions: Our results suggest an important role for OMV as an adjuvant and show how it could potentially be used when conjugated to H. influenzae PD or other safe subunit vaccine candidates.

Self-tolerance by clonal anergy of B cells is marked by an increase in IgD and decrease in IgM antigen receptor surface expression, yet the function of IgD on anergic cells is obscure. Here we define the RNA landscape of the in vivo anergy response, comprising 220 induced sequences including a core set of 97. Failure to co-express IgD with IgM decreases overall expression of receptors for self-antigen, but paradoxically increases the core anergy response, exemplified by increased Sdc1 encoding the cell surface marker syndecan-1. IgD expressed on its own is nevertheless competent to induce calcium signalling and the core anergy mRNA response. Syndecan-1 induction correlates with reduction of surface IgM and is exaggerated without surface IgD in many transitional and mature B cells. These results show that IgD attenuates the response to self-antigen in anergic cells and promotes their accumulation. In this way, IgD minimizes tolerance-induced holes in the pre-immune antibody repertoire.

BCR signaling is a central pathogenetic pathway in chronic lymphocytic leukemia (CLL). Most CLL cells express BCRs of IgM and IgD isotypes, but the contribution of these isotypes to functional responses remains incompletely defined. We therefore investigated differences between IgM and IgD signaling in freshly isolated peripheral blood CLL cells and in CLL cells cultured with nurselike cells, a model that mimics the lymph node microenvironment. IgM signaling induced prolonged activation of ERK kinases and promoted CLL cell survival, CCL3 and CCL4 chemokine secretion, and downregulation of BCL6, the transcriptional repressor of CCL3 In contrast, IgD signaling induced activation of the cytoskeletal protein HS1, along with F-actin polymerization, which resulted in rapid receptor internalization and failure to support downstream responses, including CLL cell survival and chemokine secretion. IgM and IgD receptor downmodulation, HS1 and ERK activation, chemokine secretion, and BCL6 downregulation were also observed when CLL cells were cocultured with nurselike cells. The Bruton's tyrosine kinase inhibitor ibrutinib effectively inhibited both IgM and IgD isotype signaling. In conclusion, through a variety of functional readouts, we demonstrate very distinct outcomes of IgM and IgD isotype activation in CLL cells, providing novel insight into the regulation of BCR signaling in CLL., (Copyright © 2016 by The American Association of Immunologists, Inc.)

A 74-year-old man visited our hospital with complaints of anorexia, weight loss, and impaired activities of daily living. He presented mild consciousness disturbance at the first visit, but specific causes were identified. The IgD level was>2,000 mg/dl and bone marrow biopsy was performed after aspiration failed due to excessive density. He was diagnosed with IgD/λ multiple myeloma (MM). He lapsed into a coma with an extremely high ammonia level of 484 μg/dl on day 8 after admission. His diagnosis was established as hyperammonemic encephalopathy (HE). He was treated with dexamethasone (Dex) pulse therapy and continuous hemodiafiltration. Minor improvement of hyperammonemia was achieved. Combination therapy with bortezomib and Dex was commenced. His ammonia level rapidly decreased and his mental state improved. HE accompanied by MM is rare and further studies are needed to clarify outcomes in response to treatment using the novel agent Bor. Although HE is potentially fatal, we found Bor to be rapidly effective against HE.

Background: Immune responses and safety profiles may be affected when vaccines are coadministered. We evaluated the immunogenicity, safety and reactogenicity of a booster dose of the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D-conjugate (PHiD-CV; Synflorix GSK Vaccines) and DTPa-IPV-Hib (Pediacel Sanofi Pasteur MSD) when coadministered., Methods: We performed booster assessment in a randomized controlled trial in the Netherlands. Of 780 enrolled healthy infants, 774 toddlers participated in the booster phase and received (1:1:1) (1) PHiD-CV + DTPa-HBV-IPV/Hib (Infanrix hexa, GSK Vaccines), (2) PHiD-CV + DTPa-IPV-Hib, or (3) 7-valent pneumococcal conjugate vaccine (7vCRM, Prevenar/Prevnar, Pfizer, Inc.) + DTPa-IPV-Hib at 2, 3, 4 and 11-13 months old. Blood samples were taken postprimary, prebooster, 1 and 12 months postbooster., Results: Antipneumococcal antibody responses were comparable between both PHiD-CV groups, except for serotype 18C (conjugated to tetanus toxoid). Anti-18C antibody geometric mean concentrations (GMCs) were higher when coadministered with DTPa-HBV-IPV/Hib. For each vaccine serotype, the percentages of children with antibody concentration ≥ 0.20 μg/mL were within the same ranges between PHiD-CV groups (93.8%-100%). The same was observed for the percentages of participants with opsonophagocytic activity titer ≥ 8 (90.9%-100%). When comparing both DTPa-IPV-Hib groups, postbooster antidiphtheria antibody GMCs were higher when coadministered with 7vCRM, while antitetanus and antipolyribosyl-ribitol phosphate antibody GMCs were higher with PHiD-CV coadministration. Regardless, antibody levels to these antigens were well above thresholds. Safety and reactogenicity profiles were comparable between groups., Conclusions: Coadministration of a booster dose of PHiD-CV and DTPa-IPV-Hib was immunogenic and well tolerated.

Although evolutionarily just as ancient as IgM, it has been thought for many years that IgD is not present in birds. Based on the recently sequenced genomes of 48 bird species as well as high-throughput transcriptome sequencing of immune-related tissues, we demonstrate in this work that the ostrich (Struthio camelus) possesses a functional δ gene that encodes a membrane-bound IgD H chain with seven CH domains. Furthermore, δ sequences were clearly identified in many other bird species, demonstrating that the δ gene is widely distributed among birds and is only absent in certain bird species. We also show that the ostrich possesses two μ genes (μ1, μ2) and two υ genes (υ1, υ2), in addition to the δ and α genes. Phylogenetic analyses suggest that subclass diversification of both the μ and υ genes occurred during the early stages of bird evolution, after their divergence from nonavian reptiles. Although the positions of the two υ genes are unknown, physical mapping showed that the remaining genes are organized in the order μ1-δ-α-μ2, with the α gene being inverted relative to the others. Together with previous studies, our data suggest that birds and nonavian reptile species most likely shared a common ancestral IgH gene locus containing a δ gene and an inverted α gene. The δ gene was then evolutionarily lost in selected birds, whereas the α gene lost in selected nonavian reptiles. The data obtained in this study provide significant insights into the understanding of IgH gene evolution in tetrapods., (Copyright © 2016 by The American Association of Immunologists, Inc.)

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a heterogeneous condition of unknown aetiology characterized by multiple symptoms including fatigue, post-exertional malaise and cognitive impairment, lasting for at least 6 months. Recently, two clinical trials of B cell depletion therapy with rituximab (anti-CD20) reported convincing improvement in symptoms. A possible but undefined role for B cells has therefore been proposed. Studies of the relative percentages of B cell subsets in patients with ME/CFS have not revealed any reproducible differences from healthy controls (HC). In order to explore whether more subtle alterations in B cell subsets related to B cell differentiation exist in ME/CFS patients we used flow cytometry to immunophenotype CD19⁺ B cells. The panel utilized immunoglobulin (Ig)D, CD27 and CD38 (classical B cell subsets) together with additional markers. A total of 38 patients fulfilling Canadian, Centre for Disease Control and Fukuda ME/CFS criteria and 32 age- and sex-matched HC were included. We found no difference in percentages of classical subsets between ME/CFS patients and HC. However, we observed an increase in frequency (P < 0·01) and expression (MFI; P = 0·03) of CD24 on total B cells, confined to IgD⁺ subsets. Within memory subsets, a higher frequency of CD21⁺ CD38⁻ B cells (> 20%) was associated with the presence of ME/CFS [odds ratio: 3·47 (1·15-10·46); P = 0·03] compared with HC, and there was a negative correlation with disease duration. In conclusion, we identified possible changes in B cell phenotype in patients with ME/CFS. These may reflect altered B cell function and, if confirmed in other patient cohorts, could provide a platform for studies based on clinical course or responsiveness to rituximab therapy., (© 2016 British Society for Immunology.)

Autoantibodies specific for the enzyme transglutaminase 2 (TG2) are a hallmark of the gluten-sensitive enteropathy celiac disease. Production of the Abs is strictly dependent on exposure to dietary gluten proteins, thus raising the question how a foreign Ag (gluten) can induce an autoimmune response. It has been suggested that TG2-reactive B cells are activated by gluten-reactive T cells following receptor-mediated uptake of TG2-gluten complexes. In this study, we propose a revised model that is based on the ability of the BCR to serve as a substrate to TG2 and become cross-linked to gluten-derived peptides. We show that TG2-specific IgD molecules are preferred in the reaction and that binding of TG2 via a common epitope targeted by cells using the IgH variable gene segment (IGHV)5-51 results in more efficient cross-linking. Based on these findings we hypothesize that IgD-expressing B cells using IGHV5-51 are preferentially activated, and we suggest that this property can explain the previously reported low number of somatic mutations as well as the overrepresentation of IGHV5-51 among TG2-specific plasma cells in the celiac lesion. The model also couples gluten peptide uptake by TG2-reactive B cells directly to peptide deamidation, which is necessary for the activation of gluten-reactive T cells. It thereby provides a link between gluten deamidation, T cell activation, and the production of TG2-specific Abs. These are all key events in the development of celiac disease, and by connecting them the model may explain why the same enzyme that catalyzes gluten deamidation is also an autoantigen, something that is hardly coincidental., (Copyright © 2015 by The American Association of Immunologists, Inc.)

Introduction: During HIV-1 infection the B-cell compartment undergoes profound changes towards terminal differentiation, which are only partially restored by antiretroviral therapy (cART)., Materials and Methods: To investigate the impact of infection as early as during primary HIV-1 infection (PHI) we assessed distribution of B-cell subsets in 19 PHI and 25 chronic HIV-1-infected (CHI) individuals before and during 48 weeks of cART as compared to healthy controls (n = 23). We also analysed Immunoglobulin-expression of memory B-cell subsets to identify alterations in Immunoglobulin-maturation., Results: Determination of B-cell subsets at baseline showed that total and Naive B-cells were decreased whereas Activated Memory (AM), Tissue-like Memory (TLM) B-cells and Plasma cells were increased in both PHI and CHI patients. After 4 weeks of cART total B-cells increased, while AM, TLM B-cells and Plasma cells decreased, although without reaching normal levels in either group of individuals. This trend was maintained until week 48, though only total B-cells normalized in both PHI and CHI. Resting Memory (RM) B-cells were preserved since baseline. This subset remained stable in CHI, while was expanded by an early initiation of cART during PHI. Untreated CHI patients showed IgM-overexpression at the expenses of switched (IgM-IgD-) phenotypes of the memory subsets. Interestingly, in PHI patients a significant alteration of Immunoglobulin-expression was evident at BL in TLM cells, and after 4 weeks, despite treatment, in AM and RM subsets. After 48 weeks of therapy, Immunoglobulin-expression of AM and RM almost normalized, but remained perturbed in TLM cells in both groups., Conclusions: In conclusion, aberrant activated and exhausted B-cell phenotypes rose already during PHI, while most of the alterations in Ig-expression seen in CHI appeared later, despite 4 weeks of effective cART. After 48 weeks of cART B-cell subsets distribution improved although without full normalization, while Immunoglobulin-expression normalized among AM and RM, remaining perturbed in TLM B-cells of PHI and CHI.

From paired blood and spleen samples from three adult donors, we performed high-throughput VH sequencing of human B cell subsets defined by IgD and CD27 expression: IgD(+)CD27(+) ("marginal zone [MZ]"), IgD(-)CD27(+) ("memory," including IgM ["IgM-only"], IgG and IgA) and IgD(-)CD27(-) cells ("double-negative," including IgM, IgG, and IgA). A total of 91,294 unique sequences clustered in 42,670 clones, revealing major clonal expansions in each of these subsets. Among these clones, we further analyzed those shared sequences from different subsets or tissues for VH gene mutation, H-CDR3-length, and VH/JH usage, comparing these different characteristics with all sequences from their subset of origin for which these parameters constitute a distinct signature. The IgM-only repertoire profile differed notably from that of MZ B cells by a higher mutation frequency and lower VH4 and higher JH6 gene usage. Strikingly, IgM sequences from clones shared between the MZ and the memory IgG/IgA compartments showed a mutation and repertoire profile of IgM-only and not of MZ B cells. Similarly, all IgM clonal relationships (among MZ, IgM-only, and double-negative compartments) involved sequences with the characteristics of IgM-only B cells. Finally, clonal relationships between tissues suggested distinct recirculation characteristics between MZ and switched B cells. The "IgM-only" subset (including cells with its repertoire signature but higher IgD or lower CD27 expression levels) thus appear as the only subset showing precursor-product relationships with CD27(+) switched memory B cells, indicating that they represent germinal center-derived IgM memory B cells and that IgM memory and MZ B cells constitute two distinct entities., (Copyright © 2015 by The American Association of Immunologists, Inc.)

Our knowledge about the clonal composition and intraclonal diversity of the human memory B-cell compartment and the relationship between memory B-cell subsets is still limited, although these are central issues for our understanding of adaptive immunity. We performed a deep sequencing analysis of rearranged immunoglobulin (Ig) heavy chain genes from biological replicates, covering more than 100,000 memory B lymphocytes from two healthy adults. We reveal a highly similar B-cell receptor repertoire among the four main human IgM(+) and IgG(+) memory B-cell subsets. Strikingly, in both donors, 45% of sequences could be assigned to expanded clones, demonstrating that the human memory B-cell compartment is characterized by many, often very large, B-cell clones. Twenty percent of the clones consisted of class switched and IgM(+)(IgD(+)) members, a feature that correlated significantly with clone size. Hence, we provide strong evidence that the vast majority of Ig mutated B cells--including IgM(+)IgD(+)CD27(+) B cells--are post-germinal center (GC) memory B cells. Clone members showed high intraclonal sequence diversity and high intraclonal versatility in Ig class and IgG subclass composition, with particular patterns of memory B-cell clone generation in GC reactions. In conclusion, GC produce amazingly large, complex, and diverse memory B-cell clones, equipping the human immune system with a versatile and highly diverse compartment of IgM(+)(IgD(+)) and class-switched memory B cells.

The B cell antigen receptors (BCRs) play an important role in the clonal selection of B cells and their differentiation into antibody-secreting plasma cells. Mature B cells have both immunoglobulin M (IgM) and IgD types of BCRs, which have identical antigen-binding sites and are both associated with the signaling subunits Igα and Igβ, but differ in their membrane-bound heavy chain isoforms. By two-color direct stochastic optical reconstruction microscopy (dSTORM), we showed that IgM-BCRs and IgD-BCRs reside in the plasma membrane in different protein islands with average sizes of 150 and 240 nm, respectively. Upon B cell activation, the BCR protein islands became smaller and more dispersed such that the IgM-BCRs and IgD-BCRs were found in close proximity to each other. Moreover, specific stimulation of one class of BCR had minimal effects on the organization of the other. These conclusions were supported by the findings from two-marker transmission electron microscopy and proximity ligation assays. Together, these data provide evidence for a preformed multimeric organization of BCRs on the plasma membrane that is remodeled after B cell activation., (Copyright © 2015, American Association for the Advancement of Science.)

Background: A recently-licensed 10-valent pneumococcal conjugate vaccine (PHiD-CV; Synflorix, GSK) uses Protein D from Haemophilus influenzae as a carrier protein. PHiD-CV therefore has the potential to provide additional protection against nontypeable H. influenzae (NTHi). NTHi frequently causes respiratory tract infections and is associated with significant morbidity and mortality worldwide and there is currently no vaccine., Methods: We developed mouse models of NTHi infection and influenza/NTHi superinfection. Mice were immunized with PHiD-CV, heat-killed NTHi, or a 13-valent pneumococcal conjugate vaccine that did not contain Protein D (PCV13; Prevenar, Pfizer) and then infected intranasally with NTHi., Results: Infection with NTHi resulted in weight loss, inflammation and airway neutrophilia. In a superinfection model, prior infection with pandemic H1N1 influenza virus (strain A/England/195/2009) augmented NTHi infection severity, even with a lower bacterial challenge dose. Immunization with PHiD-CV produced high levels of antibodies that were specific against Protein D, but not heat-killed NTHi. Immunization with PHiD-CV led to a slight reduction in bacterial load, but no change in disease outcome., Conclusions: PHiD-CV induced high levels of Protein D-specific antibodies, but did not augment pulmonary clearance of NTHi. We found no evidence to suggest that PHiD-CV will offer added benefit by preventing NTHi lung infection., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Memory B cells are long-lived and could contribute to persistence of humoral immunity by maintaining the plasma-cell pool or making recall responses upon re-exposure to an antigen. We determined the ability of a pneumococcal conjugate vaccine to induce anti-pneumococcal memory B cells. Frequencies of memory B cells against pneumococcal capsular polysaccharides from serotypes 1, 6B, 14, 19F and 23F were determined by cultured B cell enzyme-linked immunospot (ELISPOT) in 35 children aged 12-23 months who received pneumococcal non-typeable Haemophilus influenzae protein-D conjugate vaccine (PHiD-CV). The relationships between plasma antibodies and memory B cell frequencies were also assessed. After two doses of PHiD-CV, the proportion of subjects with detectable memory B cells against pneumococcal capsular polysaccharides increased significantly for serotypes 1 (3-45%; P < 0·01), 19F (21-66%; P < 0·01) and 23F (13-36%; P = 0·02), but not serotypes 6B (24-42%; P = 0·24) and 14 (21-40%; P = 0·06). Correlations between antibodies and memory B cells were weak. Carriage of serotype 19F at enrolment was associated with poor memory B cell responses against this serotype at subsequent time-points (day 30: non-carriers, 82% versus carriers, 0%, P < 0·01; day 210: non-carriers, 72% versus carriers, 33%, P = 0·07). PHiD-CV is capable of inducing memory B cells against some of the component pneumococcal capsular polysaccharides., (© 2015 British Society for Immunology.)

Many self-reactive B cells exist in the periphery in a rapidly reversible state of unresponsiveness referred to as anergy. Reversibility of anergy indicates that chronically occupied BCR must transduce non-durable regulatory signals that maintain unresponsiveness. Consistent with such a mechanism, studies of immunoglobulin transgenic, as well as naturally occurring polyclonal autoreactive B cells demonstrate activation of the inositol 5-phosphatase SHIP-1 in anergic cells, and low affinity chromatin autoantigen-reactive B cells have been shown to require expression of this phosphatase to maintain anergy. However, it has been reported that anergy of B cells recognizing high affinity soluble antigen may not require SHIP-1, and is instead mediated by upregulation of the inositol 3-phosphatase PTEN. To further explore this apparent difference in mechanism we analyzed the effect of B cell-targeted SHIP-1 deletion on immune tolerance of high affinity anti-HEL B cells in mice expressing soluble HEL (MD4.ML-5). We report that SHIP-1 functions to dampen responses of naïve and low-dose antigen-primed B cells in vitro, and is required for induction of B cell tolerance. Thus, while anergy of B cells reactive with low affinity and likely polyvalent chromatin antigens is maintained by activation of inhibitory signaling circuitry involving SHIP-1, anergy of B cells recognizing soluble self antigen with high affinity also requires increased activity of SHIP-1., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Although B cell depletion therapy (BCDT) is effective in a subset of rheumatoid arthritis (RA) patients, both mechanisms and biomarkers of response are poorly defined. Here we characterized abnormalities in B cell populations in RA and the impact of BCDT in order to elucidate B cell roles in the disease and response biomarkers. In active RA patients both CD27+IgD- switched memory (SM) and CD27-IgD- double negative memory (DN) peripheral blood B cells contained significantly higher fractions of CD95+ and CD21- activated cells compared to healthy controls. After BCD the predominant B cell populations were memory, and residual memory B cells displayed a high fraction of CD21- and CD95+ compared to pre-depletion indicating some resistance of these activated populations to anti-CD20. The residual memory populations also expressed more Ki-67 compared to pre-treatment, suggesting homeostatic proliferation in the B cell depleted state. Biomarkers of clinical response included lower CD95+ activated memory B cells at depletion time points and a higher ratio of transitional B cells to memory at reconstitution. B cell function in terms of cytokine secretion was dependent on B cell subset and changed with BCD. Thus, SM B cells produced pro-inflammatory (TNF) over regulatory (IL10) cytokines as compared to naïve/transitional. Notably, B cell TNF production decreased after BCDT and reconstitution compared to untreated RA. Our results support the hypothesis that the clinical and immunological outcome of BCDT depends on the relative balance of protective and pathogenic B cell subsets established after B cell depletion and repopulation.

Mature B cells express immunoglobulin M (IgM)- and IgD-isotype B cell antigen receptors, but the importance of IgD for B cell function has been unclear. By using a cellular in vitro system and corresponding mouse models, we found that antigens with low valence activated IgM receptors but failed to trigger IgD signaling, whereas polyvalent antigens activated both receptor types. Investigations of the molecular mechanism showed that deletion of the IgD-specific hinge region rendered IgD responsive to monovalent antigen, whereas transferring the hinge to IgM resulted in responsiveness only to polyvalent antigen. Our data suggest that the increased IgD/IgM ratio on conventional B-2 cells is important for preferential immune responses to antigens in immune complexes, and that the increased IgM expression on B-1 cells is essential for B-1 cell homeostasis and function.

Background: Endobronchial infections related to non-typeable Haemophilus influenzae (NTHi) are common in children and adults with suppurative airway disease such as bronchiectasis and COPD. Impaired cell mediated immune responses to NTHi have been described in these patients. Currently there are no interventions known to correct the deficiency in cell mediated immune responses to NTHi. The aim of this study was to determine if receipt of a conjugate vaccine containing protein D from H. influenzae is associated with improvement in NTHi-specific cytokine responses in children with chronic suppurative lung disease., Methods: Blood mononuclear cells from 107 young children with chronic suppurative lung disease and 32 healthy control children were stimulated in vitro with NTHi. We compared the cytokine production of stimulated mononuclear cells from children who had received the pneumococcal H. influenzae protein D conjugate vaccine with cells from children who received pneumococcal vaccines without protein D. Protein D-specific IgG1 was quantified in plasma., Results: Children with chronic suppurative lung disease who received ≥ 3 doses of the protein D conjugate vaccine produced significantly more IFNγ than children who received the alternative vaccines without protein D (median 939 versus 338 pg/ml; p = 0.007). Importantly, the amount of IFNγ produced by those vaccinated with the conjugate vaccine approached the levels observed in cells from healthy children. The conjugate vaccine was also associated with small but significant increases in IL-13 (p < 0.001) and IL-5 (p = 0.007). Protein D-specific IgG1 levels correlated with the number of PHiD-CV doses (p = 0.02)., Conclusion: Vaccination with PHiD-CV is associated with improvements in NTHi-specific cell-mediated and humoral immune responses in children with chronic suppurative lung disease., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Purposes: To investigate the possible changes in B cell subsets and in B cell expression patterns of lipid rafts (LRs) and F-actin in patients with SLE and whether leflunomide treatment may have effect on these changes., Methods: The B cell subsets and LRs expression were determined by flow cytometry and confocal microscopy, and F-actin expression was examined by confocal microscopy., Results: CD27(+)IgD(+) B cell subsets were significantly decreased while CD38(+)CD95(+) B cell subsets increased in SLE patients. The LRs levels of B cells were remarkably increased and positively correlated with SLEDAI and anti-dsDNA titer in SLE patients. The expression level of LRs was significantly higher in CD38(+) B cells than CD38(-) B cells and negatively correlated with C3 levels. The increased expression of LRs was associated with reduced expression of F-actin in the B cells from active SLE patients. Furthermore, in vitro treatment of the cells with A771726 reduced the expression level of LRs, attenuated the overaggregation of LRs, and normalized the distribution of F-actin., Conclusions: There were abnormalities in B cell subsets and LRs and F-actin expression of B cell from SLE patients. Modulation of B cell expression of LRs and F-actin by LEF could be a potential therapeutic target for SLE.

The 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) (Synflorix™) includes ten serotype-specific polysaccharides of Streptococcus pneumoniae, eight of which are conjugated individually to a nonlipidated cell-surface lipoprotein (protein D) of non-typeable H. influenzae and two of which are conjugated to nontoxic tetanus or diphtheria toxoid carrier proteins. This article provides an overview of the well-established immunogenicity of PHiD-CV, including functional immune responses and immunologic memory, as well as immune responses in preterm infants and HIV-infected children. It also includes a brief discussion of cross-protection against vaccine-related serotypes (6A and 19A) and focuses on labelling in the EU, where PHiD-CV is approved for active immunization against invasive disease, pneumonia, and acute otitis media (AOM) caused by S. pneumoniae in infants and young children up to 5 years of age. Evidence of the protective efficacy and effectiveness of PHiD-CV against pneumococcal diseases is available from several studies, including the randomized, double-blind trials COMPAS (Clinical Otitis Media and Pneumonia Study) and FinIP (Finnish Invasive Pneumococcal disease), as well as postmarketing studies from various countries. As would be expected, protection against pneumonia or AOM is substantially lower than that against invasive pneumococcal disease, as many micro-organisms other than pneumococcal vaccine serotypes can cause pneumonia and AOM, thereby limiting the overall protection of PHiD-CV against these diseases. PHiD-CV has a safety and reactogenicity profile similar to that of other pneumococcal conjugate vaccines.

Background: Alterations of B cell subset distribution have been described in the peripheral blood (PB) of rheumatoid arthritis (RA) patients, but no data are available on differences between the onset and the established phases of the disease. The purpose of the study was to clarify whether a peculiar distribution of B cell subsets characterizes RA onset, thus leading to a more favorable clinical response to treatment, and to evaluate the possible association of a particular B cell subpopulation with response to therapy., Results: 122 RA patients were enrolled: 25 had symptom duration less than 3 months and were defined as having "very early RA" (VERA), and 43 had symptom duration from more than 3 months up to one year (early-RA: ERA). The other 54 RA patients had long-standing RA (LSRA). At baseline and at 6-month follow-up visit peripheral blood samples were collected and analyzed by flow cytometry for the distribution of circulating B cell subsets by staining with surface markers CD45, CD19, CD38, CD27 and IgD and intracellular marker ZAP70.VERA and ERA patients showed higher percentages and absolute counts of circulating antigen inexperienced naïve B cells (IgD + CD27-) and lower percentages and absolute numbers of double negative (IgD-CD27-) memory B cells and plasmablasts (CD38 + CD27+) compared to LSRA patients. At the multivariate analysis, a higher frequency of naïve B cells (IgD + CD27-) at baseline arose as significant predictor of CDAI remission, together with "having VERA disease" and a low disease activity at baseline., Conclusions: The onset of RA is characterized by higher percentages and absolute numbers of naïve B cells and lower numbers of plasmablasts and double negative memory B cells compared to established RA. Naïve B cells could represent a promising biomarker of outcome.

The Mertk receptor tyrosine kinase facilitates macrophage and DC apoptotic-cell clearance and regulates immune tolerance. Mertk may also contribute to B-cell activation, because Mertk-KO mice fail to develop autoantibodies when allo-activated by T cells. We investigated this possibility with a well-characterized model in which injection of mice with goat anti-IgD antibody causes membrane IgD cross-linking that induces T-independent B cell activation and antigen presentation to T cells. Goat anti-mouse IgD antibody-injected C57BL/6 Mertk-KO mice had normal initial B cell activation and proliferation, but significantly lower T cell activation and proliferation, as well as lower IgE and IgG anti-goat IgG responses, as compared to C57BL/6 WT controls. B cell antigen processing, analyzed by evaluating B cell fluorescence following injection of monoclonal anti-IgD antibody labeled with biotin or FITC, was comparable between Mertk-KO mice and WT mice. IgD Ab primed B cells from Mertk-KO mice exhibited significantly lower ability in activating memory T cells isolated from WT mice injected with the same antigen 10 days before. These observations suggest that Mertk expression is required for optimal B-cell antigen presentation, which is, in turn, required in this model for optimal T cell activation and subsequent T cell-dependent B cell differentiation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Objective: The significance of distinct B cell abnormalities in primary Sjögren's syndrome (SS) remains to be established. We undertook this study to analyze the phenotype and messenger RNA (mRNA) transcript profiles of B cell subsets in patients with primary SS and to compare them with those in sicca syndrome patients and healthy controls., Methods: CD19+ B cells from 26 patients with primary SS, 27 sicca syndrome patients, and 22 healthy controls were analyzed by flow cytometry. Gene expression profiles of purified B cell subsets (from 3-5 subjects per group per test) were analyzed using Affymetrix gene arrays., Results: Patients with primary SS had lower frequencies of CD27+IgD- switched memory B cells and CD27+IgD+ unswitched memory B cells compared with healthy controls. Unswitched memory B cell frequencies were also lower in sicca syndrome patients and correlated inversely with serologic hyperactivity in both disease states. Further, unswitched memory B cells in primary SS had lower expression of CD1c and CD21. Gene expression analysis of CD27+ memory B cells separated patients with primary SS from healthy controls and identified a subgroup of sicca syndrome patients with a primary SS-like transcript profile. Moreover, unswitched memory B cell gene expression analysis identified 187 genes differentially expressed between patients with primary SS and healthy controls., Conclusion: A decrease in unswitched memory B cells with serologic hyperactivity is characteristic of both established primary SS and a subgroup of sicca syndrome, which suggests the value of these B cells both as biomarkers of future disease progression and for understanding disease pathogenesis. Overall, the mRNA transcript analysis of unswitched memory B cells suggests that their activation in primary SS takes place through innate immune pathways in the context of attenuated antigen-mediated adaptive signaling. Thus, our findings provide important insight into the mechanisms and potential consequences of decreased unswitched memory B cells in primary SS., (Copyright © 2014 by the American College of Rheumatology.)

The protein Zfp318 is expressed during the transition of naive B cells from an immature to mature state. To evaluate its role in mature B cell functions, a conditional gene deficiency in Zfp318 was created and deleted in bone marrow lineages via Vav-Cre. B cell development was minimally altered in the absence of the protein, although transitional 2 (T2) B cell populations were depressed in the absence of Zfp318. Intriguingly, the analysis of IgM and IgD expression by maturing and mature naive B cells demonstrated an elevated level of IgM gene products and a virtual loss of IgD products. Transcriptome analysis of Zfp318-deficient B cells revealed that only two gene products showed altered expression in the absence of Zfp318 (Ighd and Sva), demonstrating a remarkable specificity of Zfp318 action. In the absence of Zfp318, Ighm/Ighd transcripts, which would normally encode IgM and IgD from heterogeneous nuclear RNA transcripts via alternative splicing, lack intron and exon sequences from the IgD (Ighd)-encoding region. This finding indicates that Zfp318, in a novel manner, functions by repressing recognition of the transcriptional termination site at the 3' end of the terminal IgM-encoding exon, allowing for synthesis of the complete Ighm/Ighd heterogeneous nuclear RNA., (Copyright © 2014 by The American Association of Immunologists, Inc.)

Unlabelled: Various infections in the central nervous system (CNS) trigger B cell accumulation; however, the relative dynamics between viral replication and alterations in distinct B cell subsets are largely unknown. Using a glia-tropic coronavirus infection, which is initiated in the brain but rapidly spreads to and predominantly persists in the spinal cord, this study characterizes longitudinal changes in B cell subsets at both infected anatomical sites. The phase of T cell-dependent, antibody-independent control of infectious virus was associated with a similar recruitment of naive/early-activated IgD(+) IgM(+) B cells into both the brain and spinal cord. This population was progressively replaced by CD138(-) IgD(-) IgM(+) B cells, isotype-switched CD138(-) IgD(-) IgM(-) memory B cells (B(mem)), and CD138(+) antibody-secreting cells (ASC). A more rapid transition to B(mem) and ASC in spinal cord than in brain was associated with higher levels of persisting viral RNA and transcripts encoding factors promoting B cell migration, differentiation, and survival. The results demonstrate that naive/early-activated B cells are recruited early during coronavirus CNS infection but are subsequently replaced by more differentiated B cells. Furthermore, viral persistence, even at low levels, is a driving force for accumulation of isotype-switched B(mem) and ASC., Importance: Acute and chronic human CNS infections are associated with an accumulation of heterogeneous B cell subsets; however, their influence on viral load and disease is unclear. Using a glia-tropic coronavirus model, we demonstrate that the accumulation of B cells ranging from early-activated to isotype-switched differentiation stages is both temporally and spatially orchestrated. Acutely infected brains and spinal cords indiscriminately recruit a homogeneous population of early-activated B cells, which is progressively replaced by diverse, more differentiated subsets. The latter process is accelerated by elevated proinflammatory responses associated with viral persistence. The results imply that early-recruited B cells do not have antiviral function but may contribute to the inflammatory environment or act as antigen-presenting cells. Moreover, CNS viral persistence is a driving force promoting differentiated B cells with protective potential., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)