Showing papers on "Antibody published in 2011"
TL;DR: In this article, human blood CXCR5(+)CD4(+) T cells share functional properties with T follicular helper (Tfh) cells and appear to represent their circulating memory compartment.
1,263 citations
TL;DR: An antibody able to broadly neutralize both group 1 and group 2 influenza A viruses—and its target epitope—are identified and may be used for passive protection and to inform vaccine design because of its broad specificity and neutralization potency.
Abstract: The isolation of broadly neutralizing antibodies against influenza A viruses has been a long-sought goal for therapeutic approaches and vaccine design. Using a single-cell culture method for screening large numbers of human plasma cells, we isolated a neutralizing monoclonal antibody that recognized the hemagglutinin (HA) glycoprotein of all 16 subtypes and neutralized both group 1 and group 2 influenza A viruses. Passive transfer of this antibody conferred protection to mice and ferrets. Complexes with HAs from the group 1 H1 and the group 2 H3 subtypes analyzed by x-ray crystallography showed that the antibody bound to a conserved epitope in the F subdomain. This antibody may be used for passive protection and to inform vaccine design because of its broad specificity and neutralization potency.
1,146 citations
TL;DR: It is shown that TMPRSS2 might promote viral spread and pathogenesis by diminishing viral recognition by neutralizing antibodies and by activating SARS S for cell-cell and virus-cell fusion.
Abstract: The spike (S) protein of the severe acute respiratory syndrome coronavirus (SARS-CoV) can be proteolytically activated by cathepsins B and L upon viral uptake into target cell endosomes. In contrast, it is largely unknown whether host cell proteases located in the secretory pathway of infected cells and/or on the surface of target cells can cleave SARS S. We along with others could previously show that the type II transmembrane protease TMPRSS2 activates the influenza virus hemagglutinin and the human metapneumovirus F protein by cleavage. Here, we assessed whether SARS S is proteolytically processed by TMPRSS2. Western blot analysis revealed that SARS S was cleaved into several fragments upon coexpression of TMPRSS2 (cis-cleavage) and upon contact between SARS S-expressing cells and TMPRSS2-positive cells (trans-cleavage). cis-cleavage resulted in release of SARS S fragments into the cellular supernatant and in inhibition of antibody-mediated neutralization, most likely because SARS S fragments function as antibody decoys. trans-cleavage activated SARS S on effector cells for fusion with target cells and allowed efficient SARS S-driven viral entry into targets treated with a lysosomotropic agent or a cathepsin inhibitor. Finally, ACE2, the cellular receptor for SARS-CoV, and TMPRSS2 were found to be coexpressed by type II pneumocytes, which represent important viral target cells, suggesting that SARS S is cleaved by TMPRSS2 in the lung of SARS-CoV-infected individuals. In summary, we show that TMPRSS2 might promote viral spread and pathogenesis by diminishing viral recognition by neutralizing antibodies and by activating SARS S for cell-cell and virus-cell fusion.
926 citations
TL;DR: It is demonstrated that immunization of mice with synthetic nanoparticles containing antigens plus ligands that signal through TLR4 and TLR7 induces synergistic increases in antigen-specific, neutralizing antibodies compared to immunization with nanoparticles minus a single TLR ligand, and there was enhanced persistence of germinal centres and of plasma-cell responses, which persisted in the lymph nodes for >1.5 years.
Abstract: A feature of many successful vaccines is the induction of memory B cells and long-lived plasma cells that can secrete neutralizing antibodies for a lifetime. The mechanisms that stimulate such persistent responses remain poorly understood. Bali Pulendran and colleagues show that nanoparticles containing two Toll-like receptor ligands, proteins with important roles in innate immunity, can boost the magnitude and persistence of vaccine-elicited antibody responses in primates, improving vaccine-mediated protection against influenza virus. Here it is shown that nanoparticles containing two Toll-like receptor ligands can boost the magnitude and persistence of vaccine-elicited antibody responses in primates, improving vaccine-mediated protection against influenza virus. Many successful vaccines induce persistent antibody responses that can last a lifetime. The mechanisms by which they do so remain unclear, but emerging evidence indicates that they activate dendritic cells via Toll-like receptors (TLRs)1,2. For example, the yellow fever vaccine YF-17D, one of the most successful empiric vaccines ever developed3, activates dendritic cells via multiple TLRs to stimulate proinflammatory cytokines4,5. Triggering specific combinations of TLRs in dendritic cells can induce synergistic production of cytokines6, which results in enhanced T-cell responses, but its impact on antibody responses remain unknown. Learning the critical parameters of innate immunity that program such antibody responses remains a major challenge in vaccinology. Here we demonstrate that immunization of mice with synthetic nanoparticles containing antigens plus ligands that signal through TLR4 and TLR7 induces synergistic increases in antigen-specific, neutralizing antibodies compared to immunization with nanoparticles containing antigens plus a single TLR ligand. Consistent with this there was enhanced persistence of germinal centres and of plasma-cell responses, which persisted in the lymph nodes for >1.5 years. Surprisingly, there was no enhancement of the early short-lived plasma-cell response relative to that observed with single TLR ligands. Molecular profiling of activated B cells, isolated 7 days after immunization, indicated that there was early programming towards B-cell memory. Antibody responses were dependent on direct triggering of both TLRs on B cells and dendritic cells, as well as on T-cell help. Immunization protected completely against lethal avian and swine influenza virus strains in mice, and induced robust immunity against pandemic H1N1 influenza in rhesus macaques.
907 citations
TL;DR: T cells engaged by blinatumomab seem capable of eradicating chemotherapy-resistant tumor cells that otherwise cause clinical relapse in patients with MRD-positive B-lineage ALL after intensive chemotherapy.
Abstract: Purpose Blinatumomab, a bispecific single-chain antibody targeting the CD19 antigen, is a member of a novel class of antibodies that redirect T cells for selective lysis of tumor cells. In acute lymphoblastic leukemia (ALL), persistence or relapse of minimal residual disease (MRD) after chemotherapy indicates resistance to chemotherapy and results in hematologic relapse. A phase II clinical study was conducted to determine the efficacy of blinatumomab in MRD-positive B-lineage ALL.
832 citations
TL;DR: The isolation and characterization of a human monoclonal antibody CR8020 with broad neutralizing activity against most group 2 viruses, including H3N2 and H7N7, which cause severe human infection are reported.
Abstract: Current flu vaccines provide only limited coverage against seasonal strains of influenza viruses. The identification of VH1-69 antibodies that broadly neutralize almost all influenza A group 1 viruses constituted a breakthrough in the influenza field. Here, we report the isolation and characterization of a human monoclonal antibody CR8020 with broad neutralizing activity against most group 2 viruses, including H3N2 and H7N7, which cause severe human infection. The crystal structure of Fab CR8020 with the 1968 pandemic H3 hemagglutinin (HA) reveals a highly conserved epitope in the HA stalk distinct from the epitope recognized by the VH1-69 group 1 antibodies. Thus, a cocktail of two antibodies may be sufficient to neutralize most influenza A subtypes and, hence, enable development of a universal flu vaccine and broad-spectrum antibody therapies.
827 citations
TL;DR: VISTA suppresses T cell proliferation and cytokine production and can influence autoimmunity and antitumor responses in mice.
Abstract: The immunoglobulin (Ig) superfamily consists of many critical immune regulators, including the B7 family ligands and receptors. In this study, we identify a novel and structurally distinct Ig superfamily inhibitory ligand, whose extracellular domain bears homology to the B7 family ligand PD-L1. This molecule is designated V-domain Ig suppressor of T cell activation (VISTA). VISTA is primarily expressed on hematopoietic cells, and VISTA expression is highly regulated on myeloid antigen-presenting cells (APCs) and T cells. A soluble VISTA-Ig fusion protein or VISTA expression on APCs inhibits T cell proliferation and cytokine production in vitro. A VISTA-specific monoclonal antibody interferes with VISTA-induced suppression of T cell responses by VISTA-expressing APCs in vitro. Furthermore, anti-VISTA treatment exacerbates the development of the T cell-mediated autoimmune disease experimental autoimmune encephalomyelitis in mice. Finally, VISTA overexpression on tumor cells interferes with protective antitumor immunity in vivo in mice. These findings show that VISTA, a novel immunoregulatory molecule, has functional activities that are nonredundant with other Ig superfamily members and may play a role in the development of autoimmunity and immune surveillance in cancer.
580 citations
TL;DR: This novel DC-SIGN–TH2 pathway initiated by an endogenous ligand, sFc, provides an intrinsic mechanism for maintaining immune homeostasis that could be manipulated to provide therapeutic benefit in autoimmune diseases.
Abstract: High-dose intravenous immunoglobulin is a widely used therapeutic preparation of highly purified immunoglobulin G (IgG) antibodies. It is administered at high doses (1-2 grams per kilogram) for the suppression of autoantibody-triggered inflammation in a variety of clinical settings. This anti-inflammatory activity of intravenous immunoglobulin is triggered by a minor population of IgG crystallizable fragments (Fcs), with glycans terminating in α2,6 sialic acids (sFc) that target myeloid regulatory cells expressing the lectin dendritic-cell-specific ICAM-3 grabbing non-integrin (DC-SIGN; also known as CD209). Here, to characterize this response in detail, we generated humanized DC-SIGN mice (hDC-SIGN), and demonstrate that the anti-inflammatory activity of intravenous immunoglobulin can be recapitulated by the transfer of bone-marrow-derived sFc-treated hDC-SIGN(+) macrophages or dendritic cells into naive recipients. Furthermore, sFc administration results in the production of IL-33, which, in turn, induces expansion of IL-4-producing basophils that promote increased expression of the inhibitory Fc receptor FcγRIIB on effector macrophages. Systemic administration of the T(H)2 cytokines IL-33 or IL-4 upregulates FcγRIIB on macrophages, and suppresses serum-induced arthritis. Consistent with these results, transfer of IL-33-treated basophils suppressed induced arthritic inflammation. This novel DC-SIGN-T(H)2 pathway initiated by an endogenous ligand, sFc, provides an intrinsic mechanism for maintaining immune homeostasis that could be manipulated to provide therapeutic benefit in autoimmune diseases.
554 citations
TL;DR: Recent advances in understanding the biochemical, immunologic, and genetic pathogenesis of IgA nephropathy are discussed, and five distinct susceptibility loci are identified that potentially influence these processes and contain candidate mediators of disease.
Abstract: Here we discuss recent advances in understanding the biochemical, immunologic, and genetic pathogenesis of IgA nephropathy, the most common primary glomerulonephritis. Current data indicate that at least four processes contribute to development of IgA nephropathy. Patients with IgA nephropathy often have a genetically determined increase in circulating levels of IgA1 with galactose-deficient O-glycans in the hinge-region (Hit 1). This glycosylation aberrancy is, however, not sufficient to induce renal injury. Synthesis and binding of antibodies directed against galactose-deficient IgA1 are required for formation of immune complexes that accumulate in the glomerular mesangium (Hits 2 and 3). These immune complexes activate mesangial cells, inducing proliferation and secretion of extracellular matrix, cytokines, and chemokines, which result in renal injury (Hit 4). Recent genome-wide association studies identify five distinct susceptibility loci—in the MHC on chromosome 6p21, the complement factor H locus on chromosome 1q32, and in a cluster of genes on chromosome 22q22—that potentially influence these processes and contain candidate mediators of disease. The significant variation in prevalence of risk alleles among different populations may also explain some of the sizable geographic variation in disease prevalence. Elucidation of the pathogenesis of IgA nephropathy provides an opportunity to develop disease-specific therapies.
550 citations
TL;DR: It is demonstrated that aged female mice acquire a previously uncharacterized population of B cells that are called age-associated B cells (ABCs) and that these cells express integrin α(X) chain (CD11c) chain, and this unexpected population also appears in young lupus-prone mice.
538 citations
TL;DR: This work reports an extensive characterization of the therapeutic activity and mechanism of action of an anti-mouse TIM3 mAb against experimental and carcinogen-induced tumors, and for the first time defines the mechanism of antitumor action of anti-TIM3 requiring IFN-γ producing CD8(+) T cells and CD4(+) T cells correlating with therapeutic success.
Abstract: Strategies to activate and rescue exhausted tumor-specific T cells, including the use of monoclonal antibodies (mAb) that block the negative costimulatory receptors CTLA-4 and PD-1 are proving very effective, but TIM3 has been relatively neglected as a target. Here we report an extensive characterization of the therapeutic activity and mechanism of action of an anti-mouse TIM3 mAb against experimental and carcinogen-induced tumors. For the first time we specifically define the mechanism of antitumor action of anti-TIM3 requiring IFN-γ producing CD8(+) T cells and CD4(+) T cells, and a higher ratio of tumor infiltrating CD8(+):CD4(+) T cells correlating with therapeutic success. Interestingly, in some models, anti-TIM3 appeared to be effective sometime before the appearance and accumulation of significant TIM3(+)PD-1(+) T cell populations in tumor bearing mice. Anti-TIM3 displayed modest prophylactic and therapeutic activity against a small fraction of carcinogen-induced sarcomas, but comparative and combination studies of anti-TIM3 with anti-CTLA-4 and anti-PD-1 against experimental and carcinogen-induced tumors suggested that these agents might be well-tolerated and very effective in combination.
TL;DR: The fundamental knowledge of immunoglobulins found in colostrum, milk, and immune milk is summarized to describe a range of products of the bovine mammary gland that have been tested against several human diseases.
Abstract: Immunoglobulins form an important component of the immunological activity found in milk and colostrum. They are central to the immunological link that occurs when the mother transfers passive immunity to the offspring. The mechanism of transfer varies among mammalian species. Cattle provide a readily available immune rich colostrum and milk in large quantities, making those secretions important potential sources of immune products that may benefit humans. Immune milk is a term used to describe a range of products of the bovine mammary gland that have been tested against several human diseases. The use of colostrum or milk as a source of immunoglobulins, whether intended for the neonate of the species producing the secretion or for a different species, can be viewed in the context of the types of immunoglobulins in the secretion, the mechanisms by which the immunoglobulins are secreted, and the mechanisms by which the neonate or adult consuming the milk then gains immunological benefit. The stability of immunoglobulins as they undergo processing in the milk, or undergo digestion in the intestine, is an additional consideration for evaluating the value of milk immunoglobulins. This review summarizes the fundamental knowledge of immunoglobulins found in colostrum, milk, and immune milk.
TL;DR: The amenability of in vitro display to high-throughput applications broadens the prospects for their wider use in basic and applied research.
Abstract: In vitro display technologies, best exemplified by phage and yeast display, were first described for the selection of antibodies some 20 years ago. Since then, many antibodies have been selected and improved upon using these methods. Although it is not widely recognized, many of the antibodies derived using in vitro display methods have properties that would be extremely difficult, if not impossible, to obtain by immunizing animals. The first antibodies derived using in vitro display methods are now in the clinic, with many more waiting in the wings. Unlike immunization, in vitro display permits the use of defined selection conditions and provides immediate availability of the sequence encoding the antibody. The amenability of in vitro display to high-throughput applications broadens the prospects for their wider use in basic and applied research.
TL;DR: It is proposed that memory relies on swIg+ cells until they disappear and serum immunoglobulin falls to a low level, in which case memory resides with durable IgM+ reserves.
Abstract: Memory B cells formed in response to microbial antigens provide immunity to later infections; however, the inability to detect rare endogenous antigen-specific cells limits current understanding of this process. Using an antigen-based technique to enrich these cells, we found that immunization with a model protein generated B memory cells that expressed isotype-switched immunoglobulins (swIg) or retained IgM. The more numerous IgM(+) cells were longer lived than the swIg(+) cells. However, swIg(+) memory cells dominated the secondary response because of the capacity to become activated in the presence of neutralizing serum immunoglobulin. Thus, we propose that memory relies on swIg(+) cells until they disappear and serum immunoglobulin falls to a low level, in which case memory resides with durable IgM(+) reserves.
TL;DR: The purpose of this review is to summarise the current knowledge of mucosal immunoglobulins and B cells of fish MALT, and attempt to integrate the existing knowledge on both basic and applied research findings on fish mucosal immune responses to provide new directions that may facilitate the development of novel vaccination strategies.
Abstract: As physical barriers that separate teleost fish from the external environment, mucosae are also active immunological sites that protect them against exposure to microbes and stressors. In mammals, the sites where antigens are sampled from mucosal surfaces and where stimulation of naive T and B lymphocytes occurs are known as inductive sites and are constituted by mucosa-associated lymphoid tissue (MALT). According to anatomical location, the MALT in teleost fish is subdivided into gut-associated lymphoid tissue (GALT), skin-associated lymphoid tissue (SALT), and gill-associated lymphoid tissue (GIALT). All MALT contain a variety of leukocytes, including, but not limited to, T cells, B cells, plasma cells, macrophages and granulocytes. Secretory immunoglobulins are produced mainly by plasmablasts and plasma cells, and play key roles in the maintenance of mucosal homeostasis. Until recently, teleost fish B cells were thought to express only two classes of immunoglobulins, IgM and IgD, in which IgM was thought to be the only one responding to pathogens both in systemic and mucosal compartments. However, a third teleost immunoglobulin class, IgT/IgZ, was discovered in 2005, and it has recently been shown to behave as the prevalent immunoglobulin in gut mucosal immune responses. The purpose of this review is to summarise the current knowledge of mucosal immunoglobulins and B cells of fish MALT. Moreover, we attempt to integrate the existing knowledge on both basic and applied research findings on fish mucosal immune responses, with the goal to provide new directions that may facilitate the development of novel vaccination strategies that stimulate not only systemic, but also mucosal immunity.
TL;DR: Preclinical models indicate the importance of a complex integrated immune response in eliminating established tumors and validate the exploration of combinatorial treatment regimens, which are anticipated to be far more effective than monotherapies.
Abstract: Cancer immunotherapy comprises a variety of treatment approaches, incorporating the tremendous specificity of the adaptive immune system (T cells and antibodies) as well as the diverse and potent cytotoxic weaponry of both adaptive and innate immunity. Immunotherapy strategies include antitumor monoclonal antibodies, cancer vaccines, adoptive transfer of ex vivo activated T and natural killer cells, and administration of antibodies or recombinant proteins that either costimulate immune cells or block immune inhibitory pathways (so-called immune checkpoints). Although clear clinical efficacy has been demonstrated with antitumor antibodies since the late 1990s, other immunotherapies had not been shown to be effective until recently, when a spate of successes established the broad potential of this therapeutic modality. These successes are based on fundamental scientific advances demonstrating the toleragenic nature of cancer and the pivotal role of the tumor immune microenvironment in suppressing antitumor immunity. New therapies based on a sophisticated knowledge of immune-suppressive cells, soluble factors, and signaling pathways are designed to break tolerance and reactivate antitumor immunity to induce potent, long-lasting responses. Preclinical models indicate the importance of a complex integrated immune response in eliminating established tumors and validate the exploration of combinatorial treatment regimens, which are anticipated to be far more effective than monotherapies. Unlike conventional cancer therapies, most immunotherapies are active and dynamic, capable of inducing immune memory to propagate a successful rebalancing of the equilibrium between tumor and host.
TL;DR: AS03's promotion of monocytes as the principal antigen-presenting cells, and its effects on granulocytes and cytokines, may all contribute to enhancing the antigen-specific adaptive immune response.
TL;DR: M measuring anti-PLA(2)R levels by immunoassay may be a method to follow and predict response to treatment with rituximab in membranous nephropathy.
Abstract: Autoantibodies to the M-type phospholipase A2 receptor (PLA2R) are sensitive and specific for idiopathic membranous nephropathy. The anti-B cell agent rituximab is a promising therapy for this disease, but biomarkers of early response to treatment currently do not exist. Here, we investigated whether levels of anti-PLA2R correlate with the immunological activity of membranous nephropathy, potentially exhibiting a more rapid response to treatment than clinical parameters such as proteinuria. We measured the amount of anti-PLA2R using Western blot immunoassay in serial serum samples from a total of 35 patients treated with rituximab for membranous nephropathy in two distinct cohorts. Pretreatment samples from 25 of 35 (71%) patients contained anti-PLA2R, and these autoantibodies declined or disappeared in 17 (68%) of these patients within 12 months after rituximab. Those who demonstrated this immunologic response fared better clinically: 59% and 88% attained complete or partial remission by 12 and 24 months, respectively, compared with 0% and 33% among those with persistent anti-PLA2R levels. Changes in antibody levels preceded changes in proteinuria. One subject who relapsed during follow-up had a concomitant return of anti-PLA2R. In summary, measuring anti-PLA2R levels by immunoassay may be a method to follow and predict response to treatment with rituximab in membranous nephropathy.
TL;DR: Compared with monospecific anti-HER antibodies, MEHD7945A was more broadly efficacious in multiple tumor models, showing that combined inhibition of EGFR and HER3 with a single antibody is beneficial.
TL;DR: CD73 ablation significantly suppressed the growth of ovalbumin-expressing MC38 colon cancer, EG7 lymphoma, AT-3 mammary tumors, and B16F10 melanoma and it was found that the prometastatic effect of host-derived CD73 was dependent on CD73 expression on nonhematopoietic cells.
Abstract: CD73 is a cell-surface enzyme that suppresses immune responses by producing extracellular adenosine. In this study, we employed CD73 gene-targeted mice to investigate the role of host-derived CD73 on antitumor immunity and tumor cell metastasis. We found that CD73 ablation significantly suppressed the growth of ovalbumin-expressing MC38 colon cancer, EG7 lymphoma, AT-3 mammary tumors, and B16F10 melanoma. The protective effect of CD73 deficiency on primary tumors was dependent on CD8(+) T cells and associated with an increased frequency of antigen-specific CD8(+) T cells in peripheral blood and tumors and increased antigen-specific IFN-γ production. Replicate studies in bone marrow chimeras established that both hematopoietic and nonhematopoietic expression of CD73 was important to promote tumor immune escape. Using adoptive reconstitution of T regulatory cell (Treg)-depleted DEREG (depletion of regulatory T cells) mice, we demonstrated that part of the protumorigenic effect of Tregs was dependent on their expression of CD73. CD73-deficient mice were also protected against pulmonary metastasis of B16F10 melanoma cells after intravenous injection. Unexpectedly, we found that the prometastatic effect of host-derived CD73 was dependent on CD73 expression on nonhematopoietic cells. CD73 expression on nonhematopoietic cells, most likely endothelial cells, was critical for promoting lung metastasis in a manner independent from immunosuppressive effects. Notably, in vivo blockade of CD73 with a selective inhibitor or anti-CD73 monoclonal antibody significantly reduced tumor growth and metastasis of CD73-negative tumors. Taken together, our findings indicate that CD73 may be targeted at multiple levels to induce anticancer effects including at the level of tumor cells, Tregs, and nonhematopoietic cells.
TL;DR: In this paper, a robust and high-throughput flow cytometric assay was proposed to define the phagocytic activity of antigen-specific antibodies from clinical samples. But the authors did not consider the role of specific Fcγ-receptor subtypes.
TL;DR: It is demonstrated that KIR-positive NK cells can place immunological pressure on HIV-1, and that the virus can evade such NK-cell-mediated immune pressure by selecting for sequence polymorphisms, as was previously described for virus-specific T cells and neutralizing antibodies.
Abstract: Natural killer (NK) cells have an important role in the control of viral infections, recognizing virally infected cells through a variety of activating and inhibitory receptors. Epidemiological and functional studies have recently suggested that NK cells can also contribute to the control of HIV-1 infection through recognition of virally infected cells by both activating and inhibitory killer immunoglobulin-like receptors (KIRs). However, it remains unknown whether NK cells can directly mediate antiviral immune pressure in vivo in humans. Here we describe KIR-associated amino-acid polymorphisms in the HIV-1 sequence of chronically infected individuals, on a population level. We show that these KIR-associated HIV-1 sequence polymorphisms can enhance the binding of inhibitory KIRs to HIV-1-infected CD4(+) T cells, and reduce the antiviral activity of KIR-positive NK cells. These data demonstrate that KIR-positive NK cells can place immunological pressure on HIV-1, and that the virus can evade such NK-cell-mediated immune pressure by selecting for sequence polymorphisms, as was previously described for virus-specific T cells and neutralizing antibodies. NK cells might therefore have a previously underappreciated role in contributing to viral evolution.
TL;DR: Preclinical support for the development of an anti-CD47 antibody therapy for treatment of human ALL is provided, and a blocking monoclonal antibody against CD47 enabled phagocytosis of ALL cells by macrophages in vitro and inhibited tumor engraftment in vivo.
Abstract: Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy and constitutes 15% of adult leukemias. Although overall prognosis for pediatric ALL is favorable, high-risk pediatric patients and most adult patients have significantly worse outcomes. Multiagent chemotherapy is standard of care for both pediatric and adult ALL, but is associated with systemic toxicity and long-term side effects and is relatively ineffective against certain ALL subtypes. Recent efforts have focused on the development of targeted therapies for ALL including monoclonal antibodies. Here, we report the identification of CD47, a protein that inhibits phagocytosis, as an antibody target in standard and high-risk ALL. CD47 was found to be more highly expressed on a subset of human ALL patient samples compared with normal cell counterparts and to be an independent predictor of survival and disease refractoriness in several ALL patient cohorts. In addition, a blocking monoclonal antibody against CD47 enabled phagocytosis of ALL cells by macrophages in vitro and inhibited tumor engraftment in vivo . Significantly, anti-CD47 antibody eliminated ALL in the peripheral blood, bone marrow, spleen, and liver of mice engrafted with primary human ALL. These data provide preclinical support for the development of an anti-CD47 antibody therapy for treatment of human ALL. Cancer Res; 71(4); 1374–84. ©2010 AACR .
TL;DR: The current findings provide a strong rationale for the clinical use of modulators of immunosuppression with concurrent approaches to favor tumor antigen-specific immune responses, such as vaccines or adoptive transfer, in patients with cancer.
Abstract: Ipilimumab, a monoclonal antibody against cytotoxic T lymphocyte antigen 4 (CTLA-4), has been shown to improve survival in patients with advanced metastatic melanoma. It also enhances immunity to NY-ESO-1, a cancer/testis antigen expressed in a subset of patients with melanoma. To characterize the association between immune response and clinical outcome, we first analyzed NY-ESO-1 serum antibody by ELISA in 144 ipilimumab-treated patients with melanoma and found 22 of 140 (16%) seropositive at baseline and 31 of 144 (22%) seropositive following treatment. These NY-ESO-1–seropositive patients had a greater likelihood of experiencing clinical benefit 24 wk after ipilimumab treatment than NY-ESO-1–seronegative patients (P = 0.02, relative risk = 1.8, two-tailed Fisher test). To understand why some patients with NY-ESO-1 antibody failed to experience clinical benefit, we analyzed NY-ESO-1–specific CD4+ and CD8+ T-cell responses by intracellular multicytokine staining in 20 NY-ESO-1–seropositive patients and found a surprising dissociation between NY-ESO-1 antibody and CD8 responses in some patients. NY-ESO-1–seropositive patients with associated CD8+ T cells experienced more frequent clinical benefit (10 of 13; 77%) than those with undetectable CD8+ T-cell response (one of seven; 14%; P = 0.02; relative risk = 5.4, two-tailed Fisher test), as well as a significant survival advantage (P = 0.01; hazard ratio = 0.2, time-dependent Cox model). Together, our data suggest that integrated NY-ESO-1 immune responses may have predictive value for ipilimumab treatment and argue for prospective studies in patients with established NY-ESO-1 immunity. The current findings provide a strong rationale for the clinical use of modulators of immunosuppression with concurrent approaches to favor tumor antigen-specific immune responses, such as vaccines or adoptive transfer, in patients with cancer.
TL;DR: Results showed that the nanosized magnetic nanoparticles exhibited an enrichment factor (cancer cells over normal cells) of 1:10,000,000 in a magnetic field through the binding of IO-Ab on the cell surface that resulted in the preferential capture of the cancer cells.
TL;DR: Results support the use of adjuvants with flu vaccinations and could help expand coverage and decrease morbidity in the event of pandemic influenza and give vaccine makers the edge in a game of catch-up with dark horses.
Abstract: Oil-in-water adjuvants have been shown to improve immune responses against pandemic influenza vaccines as well as reduce the effective vaccine dose, increasing the number of doses available to meet global vaccine demand. Here, we use genome fragment phage display libraries and surface plasmon resonance to elucidate the effects of MF59 on the quantity, diversity, specificity, and affinity maturation of human antibody responses to the swine-origin H1N1 vaccine in different age groups. In adults and children, MF59 selectively enhanced antibody responses to the hemagglutinin 1 (HA1) globular head relative to the more conserved HA2 domain in terms of increased antibody titers as well as a more diverse antibody epitope repertoire. Antibody affinity, as inferred by greatly diminished (≥10-fold) off-rate constants, was significantly increased in toddlers and children who received the MF59-adjuvanted vaccine. Moreover, MF59 also improved antibody affinity maturation after each sequential vaccination against avian H5N1 in adults. For both pandemic influenza vaccines, there was a close correlation between serum antibody affinity and virus-neutralizing capacity. Thus, MF59 quantitatively and qualitatively enhances functional antibody responses to HA-based vaccines by improving both epitope breadth and binding affinity, demonstrating the added value of such adjuvants for influenza vaccines.
TL;DR: Recent advances in understanding of the cellular interactions and signaling pathways governing IgA production at mucosal surfaces are reviewed and new findings on the regulation and function of mucosal IgD, the most enigmatic isotype of the mucosal antibody repertoire are discussed.
Abstract: Mucosal surfaces are colonized by large communities of commensal bacteria and represent the primary site of entry for pathogenic agents. To prevent microbial intrusion, mucosal B cells release large amounts of immunoglobulin (Ig) molecules through multiple follicular and extrafollicular pathways. IgA is the most abundant antibody isotype in mucosal secretions and owes its success in frontline immunity to its ability to undergo transcytosis across epithelial cells. In addition to translocating IgA onto the mucosal surface, epithelial cells educate the mucosal immune system as to the composition of the local microbiota and instruct B cells to initiate IgA responses that generate immune protection while preserving immune homeostasis. Here we review recent advances in our understanding of the cellular interactions and signaling pathways governing IgA production at mucosal surfaces and discuss new findings on the regulation and function of mucosal IgD, the most enigmatic isotype of our mucosal antibody repertoire.
TL;DR: The results show an unexpected causal link between EBI2, an orphan G-protein-coupled receptor controlling B-cell migration, and the known immunological effects of certain oxysterols, thus uncovering a previously unknown role for this class of molecules.
Abstract: The EBI2 receptor (Epstein–Barr virus-induced gene 2, also known as GPR183) was recently shown to be linked to autoimmune disease, and is a critical regulator of the humoral immune response. It is a G-protein-coupled receptor, and its natural ligand has been unknown. Two groups now bring an end to the 'orphan' status of this receptor with identification of specific oxysterols as its natural ligands. The most potent ligand and activator is 7a,25-dihydroxycholesterol, and the EBI2–oxysterol signalling pathway has an important role in the adaptive immune response. EBI2 (also called GPR183) is an orphan G-protein-coupled receptor that is highly expressed in spleen and upregulated upon Epstein–Barr-virus infection1. Recent studies indicated that this receptor controls follicular B-cell migration and T-cell-dependent antibody production2,3,4,5,6. Oxysterols elicit profound effects on immune and inflammatory responses as well as on cholesterol metabolism7,8,9. The biological effects of oxysterols have largely been credited to the activation of nuclear hormone receptors10,11. Here we isolate oxysterols from porcine spleen extracts and show that they are endogenous ligands for EBI2. The most potent ligand and activator is 7α,25-dihydroxycholesterol (OHC), with a dissociation constant of 450 pM for EBI2. In vitro, 7α,25-OHC stimulated the migration of EBI2-expressing mouse B and T cells with half-maximum effective concentration values around 500 pM, but had no effect on EBI2-deficient cells. In vivo, EBI2-deficient B cells or normal B cells desensitized by 7α,25-OHC pre-treatment showed reduced homing to follicular areas of the spleen. Blocking the synthesis of 7α,25-OHC in vivo with clotrimazole, a CYP7B1 inhibitor, reduced the content of 7α,25-OHC in the mouse spleen and promoted the migration of adoptively transferred pre-activated B cells to the T/B boundary (the boundary between the T-zone and B-zone in the spleen follicle), mimicking the phenotype of pre-activated B cells from EBI2-deficient mice. Our results show an unexpected causal link between EBI2, an orphan G-protein-coupled receptor controlling B-cell migration, and the known immunological effects of certain oxysterols, thus uncovering a previously unknown role for this class of molecules.
TL;DR: These studies establish that human and mouse antibodies recognize distinct epitopes on the dengue virion, and indicate that antibody neutralization of DENVs is a “multi-hit” phenomenon that requires the binding of multiple antibodies to neutralize a virion.
Abstract: Dengue viruses (DENV) are the causative agents of dengue fever (DF) and dengue hemorrhagic fever (DHF). Here we review the current state of knowledge about the human antibody response to dengue and identify important knowledge gaps. A large body of work has demonstrated that antibodies can neutralize or enhance DENV infection. Investigators have mainly used mouse monoclonal antibodies (MAbs) to study interactions between DENV and antibodies. These studies indicate that antibody neutralization of DENVs is a “multi-hit” phenomenon that requires the binding of multiple antibodies to neutralize a virion. The most potently neutralizing mouse MAbs bind to surface exposed epitopes on domain III of the dengue envelope (E) protein. One challenge facing the dengue field now is to extend these studies with mouse MAbs to better understand the human antibody response. The human antibody response is complex as it involves a polyclonal response to primary and secondary infections with 4 different DENV serotypes. Here we review studies conducted with immune sera and MAbs isolated from people exposed to dengue infections. Most dengue-specific antibodies in human immune sera are weakly neutralizing and bind to multiple DENV serotypes. The human antibodies that potently and type specifically neutralize DENV represent a small fraction of the total DENV-specific antibody response. Moreover, these neutralizing antibodies appear to bind to novel epitopes including complex, quaternary epitopes that are only preserved on the intact virion. These studies establish that human and mouse antibodies recognize distinct epitopes on the dengue virion. The leading theory proposed to explain the increased risk of severe disease in secondary cases is antibody dependent enhancement (ADE), which postulates that weakly neutralizing antibodies from the first infection bind to the second serotype and enhance infection of FcγR bearing myeloid cells such as monocytes and macrophages. Here we review results from human, animal and cell culture studies relevant to the ADE hypothesis. By understanding how human antibodies neutralize or enhance DENV, it will be possible to better evaluate existing vaccines and develop the next generation of novel vaccines.