Humoral immunity and long-lived plasma cells

B cells and atherosclerosis: A HIV perspective

Atherosclerosis remains a leading cause of cardiovascular disease (CVD) globally, with the complex interplay of inflammation and lipid metabolism at its core. Recent evidence suggests a role of B cells in the pathogenesis of atherosclerosis; however, this relationship remains poorly understood, particularly in the context of HIV. We review the multifaceted functions of B cells in atherosclerosis, with a specific focus on HIV. Unique to atherosclerosis is the pivotal role of natural antibodies, particularly those targeting oxidized epitopes abundant in modified lipoproteins and cellular debris. B cells can exert control over cellular immune responses within atherosclerotic arteries through antigen presentation, chemokine production, cytokine production, and cell-cell interactions, actively participating in local and systemic immune responses. We explore how HIV, characterized by chronic immune activation and dysregulation, influences B cells in the context of atherosclerosis, potentially exacerbating CVD risk in persons with HIV. By examining the proatherogenic and antiatherogenic properties of B cells, we aim to deepen our understanding of how B cells influence atherosclerotic plaque development, especially within the framework of HIV. This research provides a foundation for novel B cell-targeted interventions, with the potential to mitigate inflammation-driven cardiovascular events, offering new perspectives on CVD risk management in PLWH.

Autoimmune Diseases and Plasma Cells Dyscrasias: Pathogenetic, Molecular and Prognostic Correlations

Multiple myeloma and monoclonal gammopathy of undetermined significance are plasma cell dyscrasias characterized by monoclonal proliferation of pathological plasma cells with uncontrolled production of immunoglobulins. Autoimmune pathologies are conditions in which T and B lymphocytes develop a tendency to activate towards self-antigens in the absence of exogenous triggers. The aim of our review is to show the possible correlations between the two pathological aspects. Molecular studies have shown how different cytokines that either cause inflammation or control the immune system play a part in the growth of immunotolerance conditions that make it easier for the development of neoplastic malignancies. Uncontrolled immune activation resulting in chronic inflammation is also known to be at the basis of the evolution toward neoplastic pathologies, as well as multiple myeloma. Another point is the impact that myeloma-specific therapies have on the course of concomitant autoimmune diseases. Indeed, cases have been observed of patients suffering from multiple myeloma treated with daratumumab and bortezomib who also benefited from their autoimmune condition or patients under treatment with immunomodulators in which there has been an arising or worsening of autoimmunity conditions. The role of bone marrow transplantation in the course of concomitant autoimmune diseases remains under analysis.

Single-cell multi-omics analysis of human testicular germ cell tumor reveals its molecular features and microenvironment

Seminoma is the most common malignant solid tumor in 14 to 44 year-old men. However, its molecular features and tumor microenvironment (TME) is largely unexplored. Here, we perform a series of studies via genomics profiling (single cell multi-omics and spatial transcriptomics) and functional examination using seminoma samples and a seminoma cell line. We identify key gene expression programs share between seminoma and primordial germ cells, and further characterize the functions of TFAP2C in promoting tumor invasion and migration. We also identify 15 immune cell subtypes in TME, and find that subtypes with exhaustion features were located closer to the tumor region through combined spatial transcriptome analysis. Furthermore, we identify key pathways and genes that may facilitate seminoma disseminating beyond the seminiferous tubules. These findings advance our knowledge of seminoma tumorigenesis and produce a multi-omics atlas of in situ human seminoma microenvironment, which could help discover potential therapy targets for seminoma.

Ex vivo engineered human plasma cells exhibit robust protein secretion and long-term engraftment in vivo

Due to their unique longevity and capacity to secrete high levels of protein, plasma B cells have the potential to be used as a cell therapy for protein replacement. Here, we show that ex vivo engineered human plasma cells exhibit single-cell RNA profiles, scanning electron micrograph ultrastructural features, and in vivo homing capacity of long-lived plasma cells. After transferring human plasma cells to immunodeficient mice in the presence of the human cytokines BAFF and IL-6, we observe increases in retention of plasma cells in the bone marrow, with engraftment exceeding a year. The most profound in vivo effects of human IL-6 are observed within 20 days of transfer and could be explained by decreased apoptosis in newly differentiated plasma cells. Collectively, these results show that ex vivo engineered and differentiated human plasma cells have the potential for long-lived in vivo protein secretion, which can be modeled in small animals.

Bone marrow derived long-lived plasma cell phenotypes are heterogeneous and can change in culture

Bone marrow derived long-lived plasma cells (LLPCs) are thought to be a major source of alloantibody in sensitized transplant patients. However, studies of LLPCs have been hampered not only by the fact that they are rare and difficult to isolate and culture but also due to the lack of consensus regarding a definitive cell-surface phenotype. The goal of the current study was to determine if LLPCs have a specific, stable cell-surface phenotype. PCs were isolated from high-volume (120 cc) bone marrow aspirates that were enriched first by negative selection then positive selection using anti-CD38 antibody-coated beads and purified by cell sorting. A typical isolation resulted in >100,000 PCs that were sorted into 4 populations with variable numbers of PCs: CD19+/CD138+/CD38Hi (64.1% of the PCs), CD19-/CD138+/CD38Hi (20.9%), CD19+/CD138-/CD38Hi (10.7%), and CD19-/CD138-/CD38Hi (4.3%). The purity of each subset was 96-99%. Each subset contained PCs secreting IgG and IgA. Measles- and tetanus-specific PCs (i.e. putative IgG secreting, antigen-specific LLPCs). LLPCs were identified in both the CD19+/CD138+/CD38Hi and CD19-/CD138+/CD38Hi subsets and in the smaller CD138- subsets (when pooled). Thus, all CD38Hi subsets contained LLPCs. Cultured PCs maintained viability (>50%) and function and could be retrieved for analyses. During 7 days of culture, cell surface expression changed from baseline in many PCs. For example, approximately 20% of CD19 + CD138+/CD38Hi cells (the largest PC subset) became CD19-. CFSE assays showed no division and only a small percentage of LLPCs were Ki-67 positive suggesting that the cells did not divide in culture and that the antibody detected was not from plasmablasts. We conclude that human bone marrow LLPCs have a heterogeneous expression of CD19 and CD138, which can change during cell culture. The fact that LLPCs were found in all four subsets raises the possibility that a large percentage of PCs in the bone marrow may be LLPCs.

Heterofunctional Particles as Single Cell Sensors to Capture Secreted Immunoglobulins and Isolate Antigen-Specific Antibody Secreting Cells

Isolating cells based on their secreted proteins remain a challenge. The authors demonstrate a capacity for high throughput single-cell protein secretion analysis and isolation based on heterofunctional particles combined with fluorescence activated cell sorting (FACS). The workflow shows that antibody secreting cells (ASCs) specific for the H1 protein from influenza virus can be isolated from B cells. The workflow consists of incubating anti-CD27 particles with the ASCs, capturing locally secreted immunoglobulins with Protein G on the particles, and identifying immunoglobulins specific to H1 via fluorescent labeled antigens followed by FACS to enrich antigen-specific ASCs. Two particles designs, Janus and mixed, are tested with hybridoma cells. Mixed particles are found to improve antibody collection, while Janus particles are found to bind target cells more effectively. Targeted hybridoma cells in coculture with non-specific hybridoma cells are identified with a sensitivity of 96% and specificity of 98%. Heterofunctional particles are used to capture ASCs that secrete antibodies specific for influenza virus from B cells from healthy adults isolated from blood after vaccination. Positive H1-tetramer sorted ASCs are validated using single ASC cultures and identify 23/56 cells specific for H1 demonstrating 164-fold enrichment from total B cells and 14.6-fold enrichment from total ASCs.

Crosstalk between endoplasmic reticulum stress and oxidative stress: a dynamic duo in multiple myeloma

Under physiological and pathological conditions, cells activate the unfolded protein response (UPR) to deal with the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum. Multiple myeloma (MM) is a hematological malignancy arising from immunoglobulin-secreting plasma cells. MM cells are subject to continual ER stress and highly dependent on the UPR signaling activation due to overproduction of paraproteins. Mounting evidence suggests the close linkage between ER stress and oxidative stress, demonstrated by overlapping signaling pathways and inter-organelle communication pivotal to cell fate decision. Imbalance of intracellular homeostasis can lead to deranged control of cellular functions and engage apoptosis due to mutual activation between ER stress and reactive oxygen species generation through a self-perpetuating cycle. Here, we present accumulating evidence showing the interactive roles of redox homeostasis and proteostasis in MM pathogenesis and drug resistance, which would be helpful in elucidating the still underdefined molecular pathways linking ER stress and oxidative stress in MM. Lastly, we highlight future research directions in the development of anti-myeloma therapy, focusing particularly on targeting redox signaling and ER stress responses.

The evolving role of rituximab in the treatment of pemphigus vulgaris: a comprehensive state-of-the-art review

INTRODUCTION

Pemphigus vulgaris (PV) is a life-threatening autoimmune mucocutaneous blistering disease. Systemic corticosteroids (CS), while life-saving, have several serious side effects. To improve treatment and prognosis, recently rituximab (RTX), a chimeric monoclonal antibody against CD20 molecule on B cells, has become popular. This Expert Opinion discusses clinical and scientifically relevant aspects of RTX treating PV.

AREA COVERED

This presentation describes the mechanism of action, clinical efficacy, safety, adverse events, protocols used, and clinical outcomes. Concerns for infection, reactivation of latent or previous infections, and high relapse rate are discussed.

EXPERT OPINION

Use of RTX in PV is still a work in progress. There are many unanswered questions. FDA did not provide a protocol or guidelines. Whenever RTX is used, systemic corticosteroids are simultaneously used, albeit for a shorter duration and lower dose. Used in these doses for these durations they can cause immunosuppression. Would it be more appropriate if instead of 'First Line Therapy' it would be more advisable to use the term 'First Adjunctive Immunosuppressive Agent'?

The role of CD24 in multiple myeloma tumorigenicity and effects of the microenvironment on its expression

Multiple myeloma (MM) is an incurable neoplasm characterized by infiltration of malignant plasma cells (PCs). Recently, the tumor microenvironment has become of great interest in MM as it known to be involved in progression and metastasis of the disease. CD24, is an adhesion molecule expressed during B cell maturation, is down regulated through the cells differentiation into PCs. Though the role of CD24 in solid cancers is well defined, its role in MM remains unknown. We aimed to understand the involvement of CD24 in MM by up-regulating its expression on MM cell lines by co-culturing the cells with bone marrow stromal cell (BMSCs). We then studied the differences between CD24+ and CD24− MM cells and found that CD24+ MM cells presented a less tumorigenic phenotype by impaired capability to migrate and to create colonies as compared with CD24− MM cells. Furthermore, there were significantly more apoptotic cells in the CD24+ fraction. Additionally, the CD24+ cells also upregulated CXCR4 expression. The decrease tumorigenicity correlated with a “more normal” PC immunophenotype in patients with MM and correlated with CD45 expression and a stronger expression of CXCR4. In summary, we found the expression of CD24 on PCs to correlate with attenuated tumorigenicity.

Tracing IgE-Producing Cells in Allergic Patients

Immunoglobulin E (IgE) is the key immunoglobulin in the pathogenesis of IgE associated allergic diseases affecting 30% of the world population. Recent data suggest that allergen-specific IgE levels in serum of allergic patients are sustained by two different mechanisms: inducible IgE production through allergen exposure, and continuous IgE production occurring even in the absence of allergen stimulus that maintains IgE levels. This assumption is supported by two observations. First, allergen exposure induces transient increases of systemic IgE production. Second, reduction in IgE levels upon depletion of IgE from the blood of allergic patients using immunoapheresis is only temporary and IgE levels quickly return to pre-treatment levels even in the absence of allergen exposure. Though IgE production has been observed in the peripheral blood and locally in various human tissues (e.g., nose, lung, spleen, bone marrow), the origin and main sites of IgE production in humans remain unknown. Furthermore, IgE-producing cells in humans have yet to be fully characterized. Capturing IgE-producing cells is challenging not only because current staining technologies are inadequate, but also because the cells are rare, they are difficult to discriminate from cells bearing IgE bound to IgE-receptors, and plasma cells express little IgE on their surface. However, due to the central role in mediating both the early and late phases of allergy, free IgE, IgE-bearing effector cells and IgE-producing cells are important therapeutic targets. Here, we discuss current knowledge and unanswered questions regarding IgE production in allergic patients as well as possible therapeutic approaches targeting IgE.

Daratumumab in Sensitized Kidney Transplantation: Potentials and Limitations of Experimental and Clinical Use

BACKGROUND

Donor-specific antibodies are associated with increased risk of antibody-mediated rejection and decreased allograft survival. Therefore, reducing the risk of these antibodies remains a clinical need in transplantation. Plasma cells are a logical target of therapy given their critical role in antibody production.

METHODS

To target plasma cells, we treated sensitized rhesus macaques with daratumumab (anti-CD38 mAb). Before transplant, we sensitized eight macaques with two sequential skin grafts from MHC-mismatched donors; four of them were also desensitized with daratumumab and plerixafor (anti-CXCR4). We also treated two patients with daratumumab in the context of transplant.

RESULTS

The animals treated with daratumumab had significantly reduced donor-specific antibody levels compared with untreated controls (57.9% versus 13% reduction; P<0.05) and prolonged renal graft survival (28.0 days versus 5.2 days; P<0.01). However, the reduction in donor-specific antibodies was not maintained because all recipients demonstrated rapid rebound of antibodies, with profound T cell-mediated rejection. In the two clinical patients, a combined heart and kidney transplant recipient with refractory antibody-mediated rejection and a highly sensitized heart transplant candidate, we also observed a significant decrease in class 1 and 2 donor-specific antibodies that led to clinical improvement of antibody-mediated rejection and to heart graft access.

CONCLUSIONS

Targeting CD38 with daratumumab significantly reduced anti-HLA antibodies and anti-HLA donor-specific antibodies in a nonhuman primate model and in two transplant clinical cases before and after transplant. This supports investigation of daratumumab as a potential therapeutic strategy; however, further research is needed regarding its use for both antibody-mediated rejection and desensitization.

Survival of Long-Lived Plasma Cells (LLPC): Piecing Together the Puzzle

Durable humoral immunity is dependent upon the generation of antigen-specific antibody titers, produced by non-proliferating bone marrow resident long-lived plasma cells (LLPC). Longevity is the hallmark of LLPC, but why and how they survive and function for years after antigen exposure is only beginning to be understood. LLPC are not intrinsically long-lived; they require continuous signals from the LLPC niche to survive. Signals unique to LLPC survival (vs. PC survival in general) most notably include those that upregulate the anti-apoptotic factor Mcl-1 and activation of the CD28 receptor expressed on LLPC. Other potential factors include expression of BCMA, upregulation of the transcription factor ZBTB20, and upregulation of the enzyme ENPP1. Metabolic fitness is another key component of LLPC longevity, facilitating the diversion of glucose to generate pyruvate during times of stress to facilitate long term survival. A third major component of LLPC survival is the microenvironment/LLPC niche itself. Cellular partners such as stromal cells, dendritic cells, and T regulatory cells establish a niche for LLPC and drive survival signaling by expressing ligands such as CD80/CD86 for CD28 and producing soluble and stromal factors that contribute to LLPC longevity. These findings have led to the current paradigm wherein both intrinsic and extrinsic mechanisms are required for the survival of LLPC. Here we outline this diverse network of signals and highlight the mechanisms thought to regulate and promote the survival of LLPC. Understanding this network of signals has direct implications in increasing our basic understanding of plasma cell biology, but also in vaccine and therapeutic drug development to address the pathologies that can arise from this subset.

Affinity maturation occurs in channel catfish (Ictalurus punctaus) following immunization with a T-cell dependent antigen

Affinity maturation of the antibody response, a process of antibody affinity increasing over response, is one of the key features of the mammalian immune system. However, the process is incompletely understood in teleost, including channel catfish (Ictalurus punctaus). In this study, IgM affinity maturation in channel catfish was investigated by estimating the kinetics of antibody affinity using ELISA and ELISPOT assays. Fish were immunized with a T-cell dependent antigen (TNP-KLH), and individual serum IgM antibody titers and affinities, and IgM⁺ antibody-secreting cells (ASCs) in peripheral blood were analyzed over a period of 14 weeks. A detectable serum anti-TNP response developed by 2-weeks post-immunization, and the maximal antibody production was observed by 6-weeks post-immunization. The average affinity of anti-TNP serum antibody increased consistently and reached the maximum by 10-weeks post-immunization. The increase of antibody affinity beyond the point of optimal antibody titer revealed that the affinity maturation of IgM antibody response occurred in channel catfish. Dissection of dynamics of individual affinity subpopulations indicated that a significant proportion of low affinity subpopulations appeared at early response, and high affinity subpopulations appeared predominantly at later, resulting in a 100-fold increase in affinity over response. Additional, TNP⁺ IgM⁺ ASCs was detected by 2-weeks post-immunization and achieved the maximal number by 6-weeks post-immunization. Using an inhibition ELISPOT assay, the findings of a consistent increase in the average affinity of secreted IgM antibody by peripheral blood ASCs, as the immune response progressed, confirmed the occurrence of the affinity maturation. Taken together, the results of this study indicated that affinity maturation occurred in channel catfish following immunization with a TD antigen TNP-KLH.

Innate-like B cell subsets during immune responses: Beyond antibody production

B lymphocytes are recognized for their crucial role in the adaptive immunity since they represent the only leukocyte lineage capable of differentiating into Ab-secreting cells. However, it has been demonstrated that these lymphocytes can exert several Ab-independent functions, including engulfing and processing Ags for presentation to T cells, secreting soluble mediators, providing co-stimulatory signals, and even participating in lymphoid tissues development. Beyond that, several reports claiming the existence of multiple B cell subsets contributing directly to innate immune responses have appeared. These "innate-like" B lymphocytes, whose phenotype, development pathways, tissue distribution, and functions are in most cases notoriously different from those of conventional B cells, are crucial to early protective responses against pathogens by exerting "crossover" defensive strategies that blur the established boundaries of innate and adaptive branches of immunity. Examples of these mechanisms include the rapid secretion of the polyspecific natural Abs, increased susceptibility to innate receptors-mediated activation, cytokine secretion, downstream priming of other innate cells, usage of specific variable immunoglobulin gene-segments, and other features. As these new insights emerge, it is becoming preponderant to redefine the functionality of B cells beyond their classical adaptive-immune tasks.

T Helper 1 Cellular Immunity Toward Recoverin Is Enhanced in Patients With Active Autoimmune Retinopathy

Autoimmune retinopathy (AIR) causes rapidly progressive vision loss that is treatable but often is confused with other forms of retinal degeneration including retinitis pigmentosa (RP). Measurement of anti-retinal antibodies (ARA) by Western blot is a commonly used laboratory assay that supports the diagnosis yet does not reflect current disease activity. To search for better diagnostic indicators, this study was designed to compare immune biomarkers and responses toward the retinal protein, recoverin, between newly diagnosed AIR patients, slow progressing RP patients and healthy controls. All individuals had measurable anti-recoverin IgG and IgM antibodies by ELISA regardless of disease status or Western blot results. Many AIR patients had elevated anti-recoverin IgG1 levels and a strong cellular response toward recoverin dominated by IFNγ. RP patients and controls responded to recoverin with a lower IFNγ response that was balanced by IL-10 production. Both AIR and RP patients displayed lower levels of total peripheral blood mononuclear cells that were due to reductions of CD4⁺ T_H cells. A comparison of messenger RNA (mRNA) for immune-related genes in whole blood of AIR patients versus RP patients or controls indicated lower expression of ATG5 and PTPN22 and higher expression of several genes involved in T_H cell signaling/transcription and adhesion. These data indicate that an immune response toward recoverin is normal in humans, but that in AIR patients the balance shifts dramatically toward higher IFNγ production and cellular activation.

Reversing Autoimmunity Combination of Rituximab and Intravenous Immunoglobulin

In this concept paper, the authors present a unique and novel protocol to treat autoimmune diseases that may have the potential to reverse autoimmunity. It uses a combination of B cell depletion therapy (BDT), specifically rituximab (RTX) and intravenous immunoglobulin (IVIg), based on a specifically designed protocol (Ahmed Protocol). Twelve infusions of RTX are given in 6–14 months. Once the CD20⁺ B cells are depleted from the peripheral blood, IVIg is given monthly until B cells repopulation occurs. Six additional cycles are given to end the protocol. During the stages of B cell depletion, repopulation and after clinical recovery, IVIg is continued. Along with clinical recovery, significant reduction and eventual disappearance of pathogenic autoantibody occurs. Administration of IVIg in the post-clinical period is a crucial part of this protocol. This combination reduces and may eventually significantly eliminates inflammation in the microenvironment and facilitates restoring immune balance. Consequently, the process of autoimmunity and the phenomenon that lead to autoimmune disease are arrested, and a sustained and prolonged disease and drug-free remission is achieved. Data from seven published studies, in which this combination protocol was used, are presented. It is known that BDT does not affect check points. IVIg has functions that mimic checkpoints. Hence, when inflammation is reduced and the microenvironment is favorable, IVIg may restore tolerance. The authors provide relevant information, molecular mechanism of action of BDT, IVIg, autoimmunity, and autoimmune diseases. The focus of the manuscript is providing an explanation, using the current literature, to demonstrate possible pathways, used by the combination of BDT and IVIg in providing sustained, long-term, drug-free remissions of autoimmune diseases, and thus reversing autoimmunity, albeit for the duration of the observation.

Molecular Aspects of Allergens and Allergy

Immunoglobulin E (IgE)-associated allergy is the most common immune disorder. More than 30% of the population suffer from symptoms of allergy which are often severe, disabling, and life threatening such as asthma and anaphylaxis. Population-based birth cohort studies show that up to 60% of the world population exhibit IgE sensitization to allergens, of which most are protein antigens. Thirty years ago the first allergen-encoding cDNAs have been isolated. In the meantime, the structures of most of the allergens relevant for disease in humans have been solved. Here we provide an update regarding what has been learned through the use of defined allergen molecules (i.e., molecular allergology) and about mechanisms of allergic disease in humans. We focus on new insights gained regarding the process of sensitization to allergens, allergen-specific secondary immune responses, and mechanisms underlying allergic inflammation and discuss open questions. We then show how molecular forms of diagnosis and specific immunotherapy are currently revolutionizing diagnosis and treatment of allergic patients and how allergen-specific approaches may be used for the preventive eradication of allergy.

Porcine epidemic diarrhea vaccine efficacy evaluation by vaccination timing and frequencies

Porcine epidemic diarrhea (PED) virus is a causative agent of enteric disease characterized by watery diarrhea and dehydration. Because PED has high morbidity and mortality, especially in suckling piglets, it causes a great economic loss to swine farms worldwide. Although various PED vaccines have been developed and commercialized, their efficacies are still controversial. In particular, current PED vaccination protocol (vaccination at 2 and 4 weeks before farrowing) may cause stress in pregnant sows. In this study, we compared the effects of PED vaccination timing and frequency for its efficacy by measuring the PED virus-specific antibodies. We found that vaccination at early stages of pregnancy induces similar levels of serum and colostrum antibodies with those at late stages of pregnancy. As the number of vaccinations increased, the amounts of antibody in serum and colostrum, and neutralizing activities increased. Our results provide important information for establishing a more efficient PED vaccination protocol.

Plasma cell output from germinal centers is regulated by signals from Tfh and stromal cells

Plasmablasts generated in germinal centers (GC) emerge at the GC–T zone interface (GTI). Zhang et al. demonstrate two major regulators of this process: Tfh-derived IL-21 and APRIL produced by CD157^high fibroblastic reticular cells located in the GTI.

Germinal centers (GCs) are the sites where B cells undergo affinity maturation. The regulation of cellular output from the GC is not well understood. Here, we show that from the earliest stages of the GC response, plasmablasts emerge at the GC–T zone interface (GTI). We define two main factors that regulate this process: Tfh-derived IL-21, which supports production of plasmablasts from the GC, and TNFSF13 (APRIL), which is produced by a population of podoplanin⁺ CD157^high fibroblastic reticular cells located in the GTI that are also rich in message for IL-6 and chemokines CXCL12, CCL19, and CCL21. Plasmablasts in the GTI express the APRIL receptor TNFRSF13B (TACI), and blocking TACI interactions specifically reduces the numbers of plasmablasts appearing in the GTI. Plasma cells generated in the GTI may provide an early source of affinity-matured antibodies that may neutralize pathogens or provide feedback regulating GC B cell selection.

Chemokines and receptors in intestinal B lymphocytes

Recent studies indicate that chemoattractant cytokines (chemokines) and their receptors modulate intestinal B lymphocytes in different ways, including regulating their maturity and differentiation in the bone marrow and homing to intestinal target tissues. Here, we review several important chemokine/chemokine receptor axes that guide intestinal B cells, focusing on the homing and migration of IgA antibody-secreting cells (IgA-ASCs) to intestinal-associated lymphoid tissues. We describe the selective regulation of these chemokine axes in coordinating the IgA-ASC trafficking in intestinal diseases. Finally, we discuss the role of B cells as chemokine producers serving dual roles in regulating the mucosal immune microenvironment.

Elicitation of Protective Antibodies against a Broad Panel of H1N1 Viruses in Ferrets Preimmune to Historical H1N1 Influenza Viruses

Most preclinical animal studies test influenza vaccines in immunologically naive animal models, even though the results of vaccination may not accurately reflect the effectiveness of vaccine candidates in humans that have preexisting immunity to influenza. In this study, novel, broadly reactive influenza vaccine candidates were assessed in preimmune ferrets. These animals were infected with different H1N1 isolates before being vaccinated or infected with another influenza virus. Previously, our group has described the design and characterization of computationally optimized broadly reactive hemagglutinin (HA) antigens (COBRA) for H1N1 isolates. Vaccinating ferrets with virus-like particle (VLP) vaccines expressing COBRA HA proteins elicited antibodies with hemagglutination inhibition (HAI) activity against more H1N1 viruses in the panel than VLP vaccines expressing wild-type HA proteins. Specifically, ferrets infected with the 1986 virus and vaccinated with a single dose of the COBRA HA VLP vaccines elicited antibodies with HAI activity against 11 to 14 of the 15 H1N1 viruses isolated between 1934 and 2013. A subset of ferrets was infected with influenza viruses expressing the COBRA HA antigens. These COBRA preimmune ferrets had superior breadth of HAI activity after vaccination with COBRA HA VLP vaccines than COBRA preimmune ferrets vaccinated with VLP vaccines expressing wild-type HA proteins. Overall, priming naive ferrets with COBRA HA based viruses or using COBRA HA based vaccines to boost preexisting antibodies induced by wild-type H1N1 viruses, COBRA HA antigens elicited sera with the broadest HAI reactivity against multiple antigenic H1N1 viral variants. This is the first report demonstrating the effectiveness of a broadly reactive or universal influenza vaccine in a preimmune ferret model.IMPORTANCE Currently, many groups are testing influenza vaccine candidates to meet the challenge of developing a vaccine that elicits broadly reactive and long-lasting protective immune responses. The goal of these vaccines is to stimulate immune responses that react against most, if not all, circulating influenza strains, over a long period of time in all populations of people. Commonly, these experimental vaccines are tested in naive animal models that do not have anti-influenza immune responses; however, humans have preexisting immunity to influenza viral antigens, particularly antibodies to the HA and NA glycoproteins. Therefore, this study investigated how preexisting antibodies to historical influenza viruses influenced HAI-specific antibodies and protective efficacy using a broadly protective vaccine candidate.

Unraveling the Role of Allo-Antibodies and Transplant Injury

Alloimmunity driving rejection in the context of solid organ transplantation can be grossly divided into mechanisms predominantly driven by either T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR), though the co-existence of both types of rejections can be seen in a variable number of sampled grafts. Acute TCMR can generally be well controlled by the establishment of effective immunosuppression (1, 2). Acute ABMR is a low frequency finding in the current era of blood group and HLA donor/recipient matching and the avoidance of engraftment in the context of high-titer, preformed donor-specific antibodies. However, chronic ABMR remains a major complication resulting in the untimely loss of transplanted organs (3-10). The close relationship between donor-specific antibodies and ABMR has been revealed by the highly sensitive detection of human leukocyte antigen (HLA) antibodies (7, 11-15). Injury to transplanted organs by activation of humoral immune reaction in the context of HLA identical transplants and the absence of donor specific antibodies (17-24), strongly suggest the participation of non-HLA (nHLA) antibodies in ABMR (25). In this review, we discuss the genesis of ABMR in the context of HLA and nHLA antibodies and summarize strategies for ABMR management.

Cellular Evidence of Telocytes as Novel Interstitial Cells Within the Magnum of Chicken Oviduct

Telocytes are a novel type of interstitial cell that has been identified in many organs of mammals, but there is little information available on these cells in avian species. This study shows the latest findings associated with telocytes in the muscular layer and lamina propria of the magnum of chicken oviduct analyzed by transmission electron microscopy. Telocytes are characterized by telopodes, which are thin and long prolongations, and a small amount of cytoplasm rich with mitochondria. Spindle- or triangular-shaped telocytes were detected at various locations in the magnum. In the muscular layer, telocytes have direct connection with smooth muscle cells. The cell body of telocytes along with their long telopodes mainly exists in the interstitial space between the smooth muscle bundles, whereas large numbers of short telopodes are scattered in between the smooth muscle cells. In the lamina propria, extremely long telopodes are twisting around each other and are usually collagen embedded. Both in the lamina propria and muscular layer, telocytes have a close relationship with other cell types, such as immune cells and blood vessels. Telopodes appear with dichotomous branching alternating between the podom and podomer, forming a 3D network structure with complex homo- and heterocellular junctions. In addition, a distinctive size of the vesicles is visible around the telopodes and may be released from telopodes because of the close relation between the vesicle and telopode. All characteristics of telocytes in the magnum indicate that telocytes may play a potential, but important, role in the pathogenesis of oviduct diseases.

B Cells Negatively Regulate the Establishment of CD49b(+)T-bet(+) Resting Memory T Helper Cells in the Bone Marrow

During an immune reaction, some antigen-experienced CD4 T cells relocate from secondary lymphoid organs (SLOs) to the bone marrow (BM) in a CD49b-dependent manner and reside and rest there as professional memory CD4 T cells. However, it remains unclear how the precursors of BM memory CD4 T cells are generated in the SLOs. While several studies have so far shown that B cell depletion reduces the persistence of memory CD4 T cells in the spleen, we here show that B cell depletion enhances the establishment of memory CD4 T cells in the BM and that B cell transfer conversely suppresses it. Interestingly, the number of antigen-experienced CD4 T cells in the BM synchronizes the number of CD49b⁺T-bet⁺ antigen-experienced CD4 T cells in the spleen. CD49b⁺T-bet⁺ antigen-experienced CD4 T cells preferentially localize in the red pulp area of the spleen and the BM in a T-bet-independent manner. We suggest that B cells negatively control the generation of CD49b⁺T-bet⁺ precursors of resting memory CD4 T cells in the spleen and may play a role in bifurcation of activated effector and resting memory CD4 T cell lineages.

Minor salivary gland evaluation: Sjögren's syndrome

BACKGROUND/AIM

 We aimed to analyze the value of 3 serial sections, spaced 200 µm apart, for quantification of lymphocyte and plasma cell foci in minor salivary gland biopsy (MSGB).

MATERIALS AND METHODS

 Labial MSGBs from 69 patients with Sjögren's syndrome (SS) and scleroderma were used for this study. Each sample was prepared as 3 serial sections spaced 200 µm apart. Lymphocytic and plasma cell focus score (LFS, PFS) were determined for each section, and the diagnostic results were compared to those obtained from a single section.

RESULTS

For 22 of the 69 patients, all 3 sections were scored at <1 and interpreted as inconclusive for the presence of SS. For 20 cases, all 3 sections were scored at ≥1 and interpreted as diagnostic for SS. In the remaining 27 cases, the score was found to vary between sections. Plasma cell foci were observed in 11 cases, with 5 cases exhibiting a PFS of ≥1. Of those 5 cases, 4 also had a LFS of ≥1.

CONCLUSION

 Assessment of 3 serial sections in MSGB has the potential to improve accuracy of SS diagnosis by detecting specific features that may not have been detected in a single section. We concluded that data about the PFS require further evaluation.

Analyzing pathogenic (double-stranded (ds) DNA-specific) plasma cells via immunofluorescence microscopy

Introduction

While protective plasma cells (PCs) are an important part of the individual’s immune defense, autoreactive plasma cells such as dsDNA-specific plasma cells contribute to the pathogenesis of autoimmune diseases like systemic lupus erythematosus (SLE). However, the research on dsDNA-specific plasma cells was restricted to the ELISpot technique, with its limitations, as no other attempt for identification of dsDNA-reactive plasma cells had been successful.

Methods

With improved fluorochrome labeling of dsDNA, removal of DNA aggregates, and enhanced blocking of unspecific binding, we were able to specifically detect dsDNA-reactive plasma cells by immunofluorescence microscopy.

Results

Via this novel technique we were able to distinguish short-lived (SLPCs) and long-lived (LLPCs) autoreactive plasma cells, discriminate dsDNA-specific plasma cells according to their immunoglobulin class (IgG, IgM, and IgA) and investigate autoreactive (dsDNA) and vaccine-induced ovalbumin (Ova) plasma cells in parallel.

Conclusions

The detection of autoreactive dsDNA-specific plasma cells via immunofluorescence microscopy allows specific studies on pathogenic and protective plasma cell subsets and their niches, detailed evaluation of therapeutic treatments and therefore offers new possibilities for basic and clinical research.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0811-2) contains supplementary material, which is available to authorized users.

Donor- and recipient-derived immunity in ABO incompatible living-related liver transplantation

This report describes how donor- and recipient-derived immunity was influenced by immunosuppressive treatment of ABO incompatibility (rituximab and immunoadsorption/plasmaphereses) in the long-term. We present an 8-year course of Hepatitis B virus (HBV) immunity, isohemagglutinins and B cell numbers. Whereas cellular HBV immunity was transferred from the HBV vaccinated donor (blood group A1) to the HBV naïve recipient (blood group 0), humoral HBV specific immune transfer was lacking. Starting at month 17 after transplantation, the recipient was vaccinated six times against HBV. Anti-HBs did not appear until the sixth vaccination at month 44. Immunoadsorption prior to transplantation reduced anti-A1 IgG titers from 256 to 2. Titers after transplantation remained low (⩽64). B cell numbers were below standard values up to month 26, then normalized and exceeded normal values from year 7 to 8 post transplantation. In conclusion, donor-derived B cell immunity was lost but recipient-derived immunity persisted after ABO incompatible transplantation.

Kinetics of hematogones in bone marrow samples from patients with non-Hodgkin lymphomas treated with rituximab-containing regimens: a flow cytometric study

Treatment with rituximab, either alone or in combination with antiblastic drugs, causes significant depletion of circulating B-lymphocytes and modifications of B cell maturation in the bone marrow. In the present study, we analyzed the kinetics of hematogones in bone marrow samples from 55 patients suffering from non-Hodgkin lymphomas and treated with rituximab-containing regimens. Maturation arrest at the level of stage 2 hematogones, along with complete depletion of naïve, mature B-lymphocytes, was observed as short-term effects (2 months after completion of chemo-immunotherapy). Further bone marrow samples, obtained 12 months after the last rituximab infusion in 21 patients undergoing long-term follow-up and treated with rituximab maintenance therapy, showed complete normalization of B-lymphocyte ontogeny. Hypogammaglobulinemia developed in 26 patients, and was still observed in nine of the 21 patients undergoing long-term follow-up. Our study provides novel data on hematogone kinetics in the setting of patients with non-Hodgkin lymphomas treated with chemo-immunotherapy containing rituximab and with rituximab maintenance. Our observations show that hypogammaglobulinemia can persist in a significant percentage of patients, despite complete recovery of B-lymphocyte ontogeny.

Quantification of HLA class II-specific memory B cells in HLA-sensitized individuals

For the quantification of HLA-specific memory B cells from peripheral blood of sensitized individuals, a limited number of methods are available. However, none of these are capable of detecting memory B cells directed at HLA class II molecules. Since the majority of antibodies that occur after transplantation appear to be specific for HLA class II, our aim was to develop an assay to detect and quantify HLA class II-specific memory B cells from peripheral blood. By using biotinylated soluble HLA class II molecules as detection agent, we were able to develop an HLA class II-specific memory B cell ELISPOT assay. The assay was validated using B cell-derived hybridomas that produce human monoclonal antibodies directed at specific HLA class II molecules. In pregnancy-immunized females, we found memory B cell frequencies ranging from 25 to 756 spots per 10(6) B cells specific for the immunizing paternal HLA class II molecules, whereas in non-immunized males no significant spot formation was detected. Here, we present a novel ELISPOT assay for quantifying HLA class II-specific memory B cells from peripheral blood. This technique provides a unique tool for monitoring the HLA class II-specific memory B cell pool in sensitized transplant recipients.

Natural IgM is produced by CD5- plasma cells that occupy a distinct survival niche in bone marrow

Natural IgM is constitutively present in the serum, where it aids in the early control of viral and bacterial expansions. Natural IgM also plays a significant role in the prevention of autoimmune disease by promoting the clearance of cellular debris. Nevertheless, the origins of natural IgM have not been precisely defined. Previous studies focused on the role of CD5(+) B1 cells in the production of natural IgM, but we show in this article that a discrete population of CD5(-) IgM plasmablasts and plasma cells in the bone marrow (BM) produces the majority of serum IgM in resting mice. These Ab-secreting cells (ASC) originate from peritoneal cavity-resident cells, because transfer of peritoneal cells completely restores serum IgM and the specific compartment of BM ASC in Rag1-deficient mice. We show that BM natural IgM ASC arise from a fetal-lineage progenitor that is neither B1a nor B1b, and that this IgM ASC compartment contains a substantial fraction of long-lived plasma cells that do not occupy the IgG plasma cell survival niche in the BM; instead, they are supported by IL-5. In summary, we identified the primary source of natural IgM and showed that these ASC are maintained long-term in a unique survival niche within the BM.

Polyclonal B cell activation for accurate analysis of pre-existing antigen-specific memory B cells

The enzyme-linked immunospot (ELISPOT) assay is a widely used tool for enumeration of antigen-specific memory B cells in several disciplines, such as vaccination, cancer immunotherapy and transplantation. For the accurate estimation of antigen-specific memory B cell frequencies, a well-defined B cell activation protocol is pivotal. In this study, we aimed to characterize a polyclonal B cell activation protocol to facilitate optimal monitoring of antigen-specific memory B cell frequencies. Total, naive and memory B cells were activated polyclonally with an α-CD40 monoclonal antibody, cytosine-phosphate-guanine (CPG) oligodeoxynucleotide (ODN) 2006, interleukin (IL)-2, IL-10 and IL-21. Polyclonal activation of B cells resulted in equal cell death ratios in naive and memory B cells. When tested in an antigen-specific system, immunoglobulin (Ig)G spots were detected only in the memory fraction. There was no change in B cell polyclonality due to in-vitro activation. Our data show that the current polyclonal activation protocol may be used reliably to estimate the frequency of memory B cells in ELISPOT assays.

IFN-γ-producing CD4+ T cells promote generation of protective germinal center-derived IgM+ B cell memory against Salmonella Typhi

Abs play a significant role in protection against the intracellular bacterium Salmonella Typhi. In this article, we investigated how long-term protective IgM responses can be elicited by a S. Typhi outer-membrane protein C- and F-based subunit vaccine (porins). We found that repeated Ag exposure promoted a CD4(+) T cell-dependent germinal center reaction that generated mutated IgM-producing B cells and was accompanied by a strong expansion of IFN-γ-secreting T follicular helper cells. Genetic ablation of individual cytokine receptors revealed that both IFN-γ and IL-17 are required for optimal germinal center reactions and production of porin-specific memory IgM(+) B cells. However, more profound reduction of porin-specific IgM B cell responses in the absence of IFN-γR signaling indicated that this cytokine plays a dominant role. Importantly, mutated IgM mAbs against porins exhibited bactericidal capacity and efficiently augmented S. Typhi clearance. In conclusion, repeated vaccination with S. Typhi porins programs type I T follicular helper cell responses that contribute to the diversification of B cell memory and promote the generation of protective IgM Abs.

Plasma cells in immunopathology: concepts and therapeutic strategies

Plasma cells are terminally differentiated B cells that secrete antibodies, important for immune protection, but also contribute to any allergic and autoimmune disease. There is increasing evidence that plasma cell populations exhibit a considerable degree of heterogeneity with respect to their immunophenotype, migration behavior, lifetime, and susceptibility to immunosuppressive drugs. Pathogenic long-lived plasma cells are refractory to existing therapies. In contrast, short-lived plasma cells can be depleted by steroids and cytostatic drugs. Therefore, long-lived plasma cells are responsible for therapy-resistant autoantibodies and resemble a challenge for the therapy of antibody-mediated autoimmune diseases. Both lifetime and therapy resistance of plasma cells are supported by factors produced within their microenviromental niches. Current results suggest that plasma cell differentiation and survival factors such as IL-6 also signal via mammalian miRNAs within the plasma cell to modulate downstream transcription factors. Recent evidence also suggests that plasma cells and/or their immediate precursors (plasmablasts) can produce important cytokines and act as antigen-presenting cells, exhibiting so far underestimated roles in immune regulation and bone homeostasis. Here, we provide an overview on plasma cell biology and discuss exciting, experimental, and potential therapeutic approaches to eliminate pathogenic plasma cells.

Pulmonary immune responses to 2009 pandemic influenza A (H1N1) virus in mice

BACKGROUND

Well-characterized mice models will afford a cheaper, easy-handling opportunity for a more comprehensive understanding of 2009 influenza A (H1N1) virus's pathogenesis potential. We aimed to provide a robust description of pulmonary immune responses in the mice infected by the virus.

METHODS

BALB/c mice were inoculated intranasally with A/Beijing/501/2009(H1N1) (BJ501) and A/PR/8/34(H1N1) (PR8) viruses and compared for survival rate, viral replication, and kinetics of pulmonary immune responses.

RESULTS

BJ501 virus replicated less efficiently in the lungs than PR8, and both caused lethal illness in the mice. The transient increases of pulmonary TNF-α 2 days post infection for BJ501 and of INF-γ and IL-10 at 6 days post infection for PR8 were observed. IL-2+ and IL-4+ secreting cells showed significant increase 12 days post infection, while IFN-γ+, IgG+ and IgA+ secreting cells increased 6 days post infection. The different patterns of pulmonary immunological parameters between two viruses were at most seen in IL-6, IL-17 secretion and IgG1/IgG2a ratio.

CONCLUSIONS

The BALB/c mouse is evaluated as a good pathogenic model for studying BJ501 2009 H1N1 virus. The work provided some basic and detailed data, which might be referred when further evaluating innate and adapted pulmonary immune responses and local viral load in mice.

Vaccine Adjuvants in Fish Vaccines Make a Difference: Comparing Three Adjuvants (Montanide ISA763A Oil, CpG/Poly I:C Combo and VHSV Glycoprotein) Alone or in Combination Formulated with an Inactivated Whole Salmonid Alphavirus Antigen

Most commercial vaccines offered to the aquaculture industry include inactivated antigens (Ag) formulated in oil adjuvants. Safety concerns are related to the use of oil adjuvants in multivalent vaccines for fish, since adverse side effects (e.g., adhesions) can appear. Therefore, there is a request for vaccine formulations for which protection will be maintained or improved, while the risk of side effects is reduced. Here, by using an inactivated salmonid alphavirus (SAV) as the test Ag, the combined use of two Toll-like receptor (TLR) ligand adjuvants, CpG oligonucleotides (ODNs) and poly I:C, as well as a genetic adjuvant consisting of a DNA plasmid vector expressing the viral haemorrhagic septicaemia virus (VHSV) glycoprotein (G) was explored. VHSV-G DNA vaccine was intramuscularly injected in combination with intraperitoneal injection of either SAV Ag alone or combined with the oil adjuvant, Montanide ISA763, or the CpG/polyI:C combo. Adjuvant formulations were evaluated for their ability to boost immune responses and induce protection against SAV in Atlantic salmon, following cohabitation challenge. It was observed that CpG/polyI:C-based formulations generated the highest neutralizing antibody titres (nAbs) before challenge, which endured post challenge. nAb responses for VHSV G-DNA- and oil-adjuvanted formulations were marginal compared to the CpG/poly I:C treatment. Interestingly, heat-inactivated sera showed reduced nAb titres compared to their non-heated counterparts, which suggests a role of complement-mediated neutralization against SAV. Consistently elevated levels of innate antiviral immune genes in the CpG/polyI:C injected groups suggested a role of IFN-mediated responses. Co-delivery of the VHSV-G DNA construct with either CpG/polyI:C or oil-adjuvanted SAV vaccine generated higher CD4 responses in head kidney at 48 h compared to injection of this vector or SAV Ag alone. The results demonstrate that a combination of pattern recognizing receptor (PRR) ligands, such as CpG/polyI:C, increases both adaptive and innate responses and represents a promising adjuvant strategy for enhancing the protection of future viral vaccines.

Persistent autoantibody-production by intermediates between short-and long-lived plasma cells in inflamed lymph nodes of experimental epidermolysis bullosa acquisita

Autoantibodies are believed to be maintained by either the continuous generation of short-lived plasma cells in secondary lymphoid tissues or by long-lived plasma cells localized in bone marrow and spleen. Here, we show in a mouse model for the autoimmune blistering skin disease epidermolysis bullosa acquisita (EBA) that chronic autoantibody production can also be maintained in inflamed lymph nodes, by plasma cells exhibiting intermediate lifetimes. After EBA induction by immunization with a mCOL7c-GST-fusion protein, antigen-specific plasma cells and CD4 T cells were analyzed. Plasma cells were maintained for months in stable numbers in the draining lymph nodes, but not in spleen and bone marrow. In contrast, localization of mCOL7c-GST -specific CD4 T cells was not restricted to lymph nodes, indicating that availability of T cell help does not limit plasma cell localization to this site. BrdU-incorporation studies indicated that pathogenic mCOL7c- and non-pathogenic GST-specific plasma cells resemble intermediates between short-and long-lived plasma cells with half-lives of about 7 weeks. Immunization with mCOL7c-GST also yielded considerable numbers of plasma cells neither specific for mCOL7c- nor GST. These bystander-activated plasma cells exhibited much shorter half-lives and higher population turnover, suggesting that plasma cell lifetimes were only partly determined by the lymph node environment but also by the mode of activation. These results indicate that inflamed lymph nodes can harbor pathogenic plasma cells exhibiting distinct properties and hence may resemble a so far neglected site for chronic autoantibody production.

The ABCs (Antibody, B Cells, and Carbohydrate Epitopes) of Cholera Immunity: Considerations for an Improved Vaccine

Cholera, a diarrheal disease, is known for explosive epidemics that can quickly kill thousands. Endemic cholera is a seasonal torment that also has a significant mortality. Not all nations with extensive rural communities can achieve the required infrastructure or behavioral changes to prevent epidemic or endemic cholera. For some communities, a single-dose cholera vaccine that protects those at risk is the most efficacious means to reduce morbidity and mortality. It is clear that our understanding of what a protective cholera immune response is has not progressed at the rate our understanding of the pathogenesis and molecular biology of cholera infection has. This review addresses V. cholerae lipopolysaccharide (LPS)-based immunogens because LPS is the only immunogen proven to induce protective antibody in humans. We discuss the role of anti-LPS antibodies in protection from cholera, the importance and the potential role of B cell subsets in protection that is based on their anatomical location and the intrinsic antigen-receptor specificity of various subsets is introduced.

The hierarchical process of differentiation of long-lived antibody-secreting cells is dependent on integrated signals derived from antigen and IL-17A

Switched CD19-positive memory B cells purified from mice with chronic immune response against Thalassophrynenattereri venom proteins were cultured with venom or cytokines. Our results confirm the existence of a hierarchic process of differentiation: activated memory B cells progressively acquire increasing levels of CD138 and decreasing levels of CD45R/B220 to finally arrive at ASC with B220^neg phenotype, which are IgG1-secreting cells. Only Bmem from peritoneal cavity or bone marrow of VTn immunized mice presented the capacity to generate ASC functionally active. IL-17A or IL-21/IL-23/IL-33 improves the ability of venom to induce intracellular IgG of peritoneal derived-ASC. Cognate stimulation with venom and IL-17A is sufficient to down-regulate the expression of CD45R/B220. BAFF-R is up-regulated in splenic or medullar derived-ASC stimulated by venom, CpG or cytokines. Only splenic derived-ASC up-regulate Bcl-2 expression after CpG or the combination of IL-21/IL-23/IL-33 stimulation. Finally, the activation of ASC for IgG1 secretion is triggered by venom proteins in peritoneal cavity and by IL-17A in medullar niche. These results show the importance of the integration of signals downstream of BCR and IL17-A receptors in modulating ASC differentiation, focusing in the microenvironment niche of their generation.

Dry eye as a mucosal autoimmune disease

Dry eye is a common ocular surface inflammatory disease that significantly affects quality of life. Dysfunction of the lacrimal function unit (LFU) alters tear composition and breaks ocular surface homeostasis, facilitating chronic inflammation and tissue damage. Accordingly, the most effective treatments to date are geared towards reducing inflammation and restoring normal tear film. The pathogenic role of CD4+ T cells is well known, and the field is rapidly realizing the complexity of other innate and adaptive immune factors involved in the development and progression of disease. The data support the hypothesis that dry eye is a localized autoimmune disease originating from an imbalance in the protective immunoregulatory and proinflammatory pathways of the ocular surface.

Optimization and qualification of a memory B-cell ELISpot for the detection of vaccine-induced memory responses in HIV vaccine trials

Various aspects of the human immune system can be analyzed to determine the efficacy of a vaccine. We have developed a B-cell ELISpot to measure HIV-specific antibody-secreting B cells in the peripheral blood as a result of vaccination or natural infection. Our method includes stimulating peripheral blood mononuclear cells with interleukin-2 and a polyclonal activator, R848, to induce memory B cells to differentiate into antibody-secreting cells. Total immunoglobulin-secreting as well as antigen-specific B cells are then quantified. We have tested several HIV Env gp120 and gp140 proteins from different HIV subtypes, as well as a sensitive consensus group M Env gp140. Our findings indicate that the B-cell ELISpot provides a sensitive and specific tool to detect antigen-specific memory B-cell responses, and it is equally suited to detect antibody-secreting plasmablasts present in the circulation shortly after infection or vaccination.

Molecular pathogenesis of neuromyelitis optica

Neuromyelitis optica (NMO) is a rare autoimmune disorder, distinct from multiple sclerosis, causing inflammatory lesions in the optic nerves and spinal cord. An autoantibody (NMO IgG) against aquaporin-4 (AQP4), a water channel expressed on astrocytes is thought to be causative. Peripheral production of the antibody is triggered by an unknown process in genetically susceptible individuals. Anti-AQP4 antibody enters the central nervous system (CNS) when the blood brain barrier is made permeable and has high affinity for orthogonal array particles of AQP4. Like other autoimmune diseases, Th17 cells and their effector cytokines (such as interleukin 6) have been implicated in pathogenesis. AQP4 expressing peripheral organs are not affected by NMO IgG, but the antibody causes extensive astrocytic loss in specific regions of the CNS through complement mediated cytotoxicity. Demyelination occurs during the inflammatory process and is probably secondary to oligodendrocyte apoptosis subsequent to loss of trophic support from astrocytes. Ultimately, extensive axonal injury leads to severe disability. Despite rapid advances in the understanding of NMO pathogenesis, unanswered questions remain, particularly with regards to disease mechanisms in NMO IgG seronegative cases. Increasing knowledge of the molecular pathology is leading to improved treatment strategies.