Showing papers on "Antibody published in 2012"

Immune-Correlates Analysis of an HIV-1 Vaccine Efficacy Trial

Abstract: Background In the RV144 trial, the estimated efficacy of a vaccine regimen against human immunodeficiency virus type 1 (HIV-1) was 31.2%. We performed a case–control analysis to identify antibody and cellular immune correlates of infection risk. Methods In pilot studies conducted with RV144 blood samples, 17 antibody or cellular assays met prespecified criteria, of which 6 were chosen for primary analysis to determine the roles of T-cell, IgG antibody, and IgA antibody responses in the modulation of infection risk. Assays were performed on samples from 41 vaccinees who became infected and 205 uninfected vaccinees, obtained 2 weeks after final immunization, to evaluate whether immune-response variables predicted HIV-1 infection through 42 months of follow-up. Results Of six primary variables, two correlated significantly with infection risk: the binding of IgG antibodies to variable regions 1 and 2 (V1V2) of HIV-1 envelope proteins (Env) correlated inversely with the rate of HIV-1 infection (estimated odds...

IgE and mast cells in allergic disease

Abstract: Immunoglobulin E (IgE) antibodies and mast cells have been so convincingly linked to the pathophysiology of anaphylaxis and other acute allergic reactions that it can be difficult to think of them in other contexts. However, a large body of evidence now suggests that both IgE and mast cells are also key drivers of the long-term pathophysiological changes and tissue remodeling associated with chronic allergic inflammation in asthma and other settings. Such potential roles include IgE-dependent regulation of mast-cell functions, actions of IgE that are largely independent of mast cells and roles of mast cells that do not directly involve IgE. In this review, we discuss findings supporting the conclusion that IgE and mast cells can have both interdependent and independent roles in the complex immune responses that manifest clinically as asthma and other allergic disorders.

Immune Inhibitory Molecules LAG-3 and PD-1 Synergistically Regulate T-cell Function to Promote Tumoral Immune Escape

Abstract: Inhibitory receptors on immune cells are pivotal regulators of immune escape in cancer. Among these inhibitory receptors, CTLA-4 (targeted clinically by ipilimumab) serves as a dominant off-switch while other receptors such as PD-1 and LAG-3 seem to serve more subtle rheostat functions. However, the extent of synergy and cooperative interactions between inhibitory pathways in cancer remain largely unexplored. Here, we reveal extensive coexpression of PD-1 and LAG-3 on tumor-infiltrating CD4(+) and CD8(+) T cells in three distinct transplantable tumors. Dual anti-LAG-3/anti-PD-1 antibody treatment cured most mice of established tumors that were largely resistant to single antibody treatment. Despite minimal immunopathologic sequelae in PD-1 and LAG-3 single knockout mice, dual knockout mice abrogated self-tolerance with resultant autoimmune infiltrates in multiple organs, leading to eventual lethality. However, Lag3(-/-)Pdcd1(-/-) mice showed markedly increased survival from and clearance of multiple transplantable tumors. Together, these results define a strong synergy between the PD-1 and LAG-3 inhibitory pathways in tolerance to both self and tumor antigens. In addition, they argue strongly that dual blockade of these molecules represents a promising combinatorial strategy for cancer.

Immune Regulatory Function of B Cells

Abstract: B cells are regarded for their capacity to produce antibody. However, recent advances in B cell biology have capitalized on old findings and demonstrated that B cells also release a broad variety of cytokines. As with T helper cells, B cells can be classified into subsets according to the cytokine milieu that they produce. One functional B cell subset, regulatory B cells (Bregs), has recently been shown to contribute to the maintenance of the fine equilibrium required for tolerance. Bregs restrain the excessive inflammatory responses that occur during autoimmune diseases or that can be caused by unresolved infections. Pivotal to Breg function is interleukin-10 (IL-10), which inhibits proinflammatory cytokines and supports regulatory T cell differentiation. This review reports and discusses the factors that are important for Breg differentiation and for their effector function in both mouse and human.

Preexisting influenza-specific CD4+ T cells correlate with disease protection against influenza challenge in humans

Abstract: Protective immunity against influenza virus infection is mediated by neutralizing antibodies, but the precise role of T cells in human influenza immunity is uncertain. We conducted influenza infection studies in healthy volunteers with no detectable antibodies to the challenge viruses H3N2 or H1N1. We mapped T cell responses to influenza before and during infection. We found a large increase in influenza-specific T cell responses by day 7, when virus was completely cleared from nasal samples and serum antibodies were still undetectable. Preexisting CD4+, but not CD8+, T cells responding to influenza internal proteins were associated with lower virus shedding and less severe illness. These CD4+ cells also responded to pandemic H1N1 (A/CA/07/2009) peptides and showed evidence of cytotoxic activity. These cells are an important statistical correlate of homotypic and heterotypic response and may limit severity of influenza infection by new strains in the absence of specific antibody responses. Our results provide information that may aid the design of future vaccines against emerging influenza strains.

Highly Conserved Protective Epitopes on Influenza B Viruses

Abstract: Identification of broadly neutralizing antibodies against influenza A viruses has raised hopes for the development of monoclonal antibody-based immunotherapy and "universal" vaccines for influenza. However, a substantial part of the annual flu burden is caused by two cocirculating, antigenically distinct lineages of influenza B viruses. Here, we report human monoclonal antibodies, CR8033, CR8071, and CR9114, that protect mice against lethal challenge from both lineages. Antibodies CR8033 and CR8071 recognize distinct conserved epitopes in the head region of the influenza B hemagglutinin (HA), whereas CR9114 binds a conserved epitope in the HA stem and protects against lethal challenge with influenza A and B viruses. These antibodies may inform on development of monoclonal antibody-based treatments and a universal flu vaccine for all influenza A and B viruses.

IgG Placental Transfer in Healthy and Pathological Pregnancies

Abstract: Placental transfer of maternal IgG antibodies to the fetus is an important mechanism that provides protection to the infant while his/her humoral response is inefficient. IgG is the only antibody class that significantly crosses the human placenta. This crossing is mediated by FcRn expressed on syncytiotrophoblast cells. There is evidence that IgG transfer depends on the following: (i) maternal levels of total IgG and specific antibodies, (ii) gestational age, (iii) placental integrity, (iv) IgG subclass, and (v) nature of antigen, being more intense for thymus-dependent ones. These features represent the basis for maternal immunization strategies aimed at protecting newborns against neonatal and infantile infectious diseases. In some situations, such as mothers with primary immunodeficiencies, exogenous IgG acquired by intravenous immunoglobulin therapy crosses the placenta in similar patterns to endogenous immunoglobulins and may also protect the offspring from infections in early life. Inversely, harmful autoantibodies may cross the placenta and cause transitory autoimmune disease in the neonate.

B cell–helper neutrophils stimulate the diversification and production of immunoglobulin in the marginal zone of the spleen

Abstract: Follicular T cells provide help to B cells to elicit antibody responses. Cerutti and colleagues show that neutrophils provide help to marginal-zone B cells that produce T cell–independent antibodies.

Mechanisms of allergen-specific immunotherapy

Abstract: Allergen-specific immunotherapy (allergen-SIT) is a potentially curative treatment approach in allergic diseases. It has been used for almost 100 years as a desensitizing therapy. The induction of peripheral T cell tolerance and promotion of the formation of regulatory T-cells are key mechanisms in allergen-SIT. Both FOXP3+CD4+CD25+ regulatory T (Treg) cells and inducible IL-10- and TGF-β-producing type 1 Treg (Tr1) cells may prevent the development of allergic diseases and play a role in successful allergen-SIT and healthy immune response via several mechanisms. The mechanisms of suppression of different pro-inflammatory cells, such as eosinophils, mast cells and basophils and the development of allergen tolerance also directly or indirectly involves Treg cells. Furthermore, the formation of non-inflammatory antibodies particularly IgG4 is induced by IL-10. Knowledge of these molecular basis is crucial in the understanding the regulation of immune responses and their possible therapeutic targets in allergic diseases.

B cell depletion therapy ameliorates autoimmune disease through ablation of IL-6–producing B cells

Abstract: B cells have paradoxical roles in autoimmunity, exerting both pathogenic and protective effects. Pathogenesis may be antibody independent, as B cell depletion therapy (BCDT) leads to amelioration of disease irrespective of autoantibody ablation. However, the mechanisms of pathogenesis are poorly understood. We demonstrate that BCDT alleviates central nervous system autoimmunity through ablation of IL-6–secreting pathogenic B cells. B cells from mice with experimental autoimmune encephalomyelitis (EAE) secreted elevated levels of IL-6 compared with B cells from naive controls, and mice with a B cell–specific IL-6 deficiency showed less severe disease than mice with wild-type B cells. Moreover, BCDT ameliorated EAE only in mice with IL-6–sufficient B cells. This mechanism of pathogenesis may also operate in multiple sclerosis (MS) because B cells from MS patients produced more IL-6 than B cells from healthy controls, and this abnormality was normalized with B cell reconstitution after Rituximab treatment. This suggests that BCDT improved disease progression, at least partly, by eliminating IL-6–producing B cells in MS patients. Taking these data together, we conclude that IL-6 secretion is a major mechanism of B cell–driven pathogenesis in T cell–mediated autoimmune disease such as EAE and MS.

Immunopathology of autoantibody-associated encephalitides: clues for pathogenesis

Abstract: Classical paraneoplastic encephalitis syndromes with 'onconeural' antibodies directed to intracellular antigens, and the recently described paraneoplastic or non-paraneoplastic encephalitides and antibodies against both neural surface antigens (voltage-gated potassium channel-complexes, N-methyl-d-aspartate receptors) and intracellular antigens (glutamic acid decarboxylase-65), constitute an increasingly recognized group of immune-mediated brain diseases. Evidence for specific immune mechanisms, however, is scarce. Here, we report qualitative and quantitative immunopathology in brain tissue (biopsy or autopsy material) of 17 cases with encephalitis and antibodies to either intracellular (Hu, Ma2, glutamic acid decarboxylase) or surface antigenic targets (voltage-gated potassium channel-complex or N-methyl-d-aspartate receptors). We hypothesized that the encephalitides with antibodies against intracellular antigens (intracellular antigen-onconeural and intracellular antigen-glutamic acid decarboxylase groups) would show neurodegeneration mediated by T cell cytotoxicity and the encephalitides with antibodies against surface antigens would be antibody-mediated and would show less T cell involvement. We found a higher CD8/CD3 ratio and more frequent appositions of granzyme-B(+) cytotoxic T cells to neurons, with associated neuronal loss, in the intracellular antigen-onconeural group (anti-Hu and anti-Ma2 cases) compared to the patients with surface antigens (anti-N-methyl-d-aspartate receptors and anti-voltage-gated potassium channel complex cases). One of the glutamic acid decarboxylase antibody encephalitis cases (intracellular antigen-glutamic acid decarboxylase group) showed multiple appositions of GrB-positive T cells to neurons. Generally, however, the glutamic acid decarboxylase antibody cases showed less intense inflammation and also had relatively low CD8/CD3 ratios compared with the intracellular antigen-onconeural cases. Conversely, we found complement C9neo deposition on neurons associated with acute neuronal cell death in the surface antigen group only, specifically in the voltage-gated potassium channel-complex antibody patients. N-methyl-d-aspartate receptors-antibody cases showed no evidence of antibody and complement-mediated tissue injury and were distinguished from all other encephalitides by the absence of clear neuronal pathology and a low density of inflammatory cells. Although tissue samples varied in location and in the stage of disease, our findings strongly support a central role for T cell-mediated neuronal cytotoxicity in encephalitides with antibodies against intracellular antigens. In voltage-gated potassium channel-complex encephalitis, a subset of the surface antigen antibody encephalitides, an antibody- and complement-mediated immune response appears to be responsible for neuronal loss and cerebral atrophy; the apparent absence of these mechanisms in N-methyl-d-aspartate receptors antibody encephalitis is intriguing and requires further study.

Obesity is associated with impaired immune response to influenza vaccination in humans

Abstract: Obesity is an independent risk factor for morbidity and mortality from pandemic influenza H1N1. Influenza is a significant public health threat, killing an estimated 250 000–500 000 people worldwide each year. More than one in ten of the world's adult population is obese and more than two-thirds of the US adult population is overweight or obese. No studies have compared humoral or cellular immune responses to influenza vaccination in healthy weight, overweight and obese populations despite clear public health importance. The study employed a convenience sample to determine the antibody response to the 2009–2010 inactivated trivalent influenza vaccine (TIV) in healthy weight, overweight and obese participants at 1 and 12 months post vaccination. In addition, activation of CD8+ T cells and expression of interferon-γ and granzyme B were measured in influenza-stimulated peripheral blood mononuclear cell (PBMC) cultures. Body mass index (BMI) correlated positively with higher initial fold increase in IgG antibodies detected by enzyme-linked immunosorbent assay to TIV, confirmed by HAI antibody in a subset study. However, 12 months post vaccination, higher BMI was associated with a greater decline in influenza antibody titers. PBMCs challenged ex vivo with vaccine strain virus, demonstrated that obese individuals had decreased CD8+ T-cell activation and decreased expression of functional proteins compared with healthy weight individuals. These results suggest obesity may impair the ability to mount a protective immune response to influenza virus.

Anti-pd-l1 antibodies and uses thereof

Abstract: The present application relates to anti-PD-L1 antibodies or antigen binding fragments thereof, nucleic acid encoding the same, therapeutic compositions thereof, and their use to enhance T-cell function to upregulate cell-mediated immune responses and for the treatment of T cell dysfunctional disorders, such as tumor immunity, for the treatment of and cancer.

Morvan syndrome: Clinical and serological observations in 29 cases

Abstract: Objective: A study was undertaken to describe the clinical spectrum, voltage-gated potassium channel (VGKC) complex antibody specificities, and central nervous system localization of antibody binding in 29 patients diagnosed with Morvan syndrome (MoS). Methods: Clinical data were collected using questionnaires. Radioimmunoassay, cell-based assays, and mouse brain immunohistochemistry were used to characterize the serum antibodies. Results: Neuromyotonia (100%), neuropsychiatric features (insomnia 89.7%, confusion 65.5%, amnesia 55.6%, hallucinations 51.9%), dysautonomia (hyperhidrosis 86.2%, cardiovascular 48.3%), and neuropathic pain (62.1%) were the most common manifestations. A total of 93.1% of MoS patients were male. VGKC-complex antibodies were present in 23 of 29 (79%) MoS patients at referral; 24 of 27 available sera had CASPR2, LGI1, or both CASPR2 and LGI1 antibodies (3 also with contactin-2 antibodies). CASPR2 antibodies were generally higher titer than LGI1 antibodies. Tumors (41.4%), mainly thymomas, were associated with CASPR2 antibodies and a poor prognosis, whereas LGI1 antibodies were associated with serum hyponatremia. In brain tissue regions including the hypothalamus, raphe, and locus coeruleus, commercial antibodies to LGI1 bound to neuronal cell bodies including the antidiuretic hormone-secreting and orexin-secreting hypothalamic neurons, whereas CASPR2 commercial antibodies bound more often to the neuropil. MoS antibodies bound similarly, but there was evidence of additional antibodies in some sera that were not adsorbed by LGI1- or CASPR2-expressing cells and bound to mouse Caspr2−/− tissue. Interpretation: MoS is clinically distinct from other VGKC-complex antibody-associated conditions, and usually is associated with high-titer CASPR2 antibodies, often accompanied by lower-titer LGI1 antibodies. CASPR2 and LGI1 antibodies bind to multiple brain regions, which helps to explain the multifocal clinical features of this disease, but other antibodies are likely to play a role in some patients and need to be characterized in future studies. ANN NEUROL 2012;

Robust tumor immunity to melanoma mediated by interleukin-9-producing T cells

Abstract: Interleukin-9 (IL-9) is a T cell cytokine that acts through a γC-family receptor on target cells and is associated with inflammation and allergy. We determined that T cells from mice deficient in the T helper type 17 (T(H)17) pathway genes encoding retinoid-related orphan receptor γ (ROR-γ) and IL-23 receptor (IL-23R) produced abundant IL-9, and we found substantial growth inhibition of B16F10 melanoma in these mice. IL-9-blocking antibodies reversed this tumor growth inhibition and enhanced tumor growth in wild-type (WT) mice. Il9r(-/-) mice showed accelerated tumor growth, and administration of recombinant IL-9 (rIL-9) to tumor-bearing WT and Rag1(-/-) mice inhibited melanoma as well as lung carcinoma growth. Adoptive transfer of tumor-antigen-specific T(H)9 cells into both WT and Rag1(-/-) mice suppressed melanoma growth; this effect was abrogated by treatment with neutralizing antibodies to IL-9. Exogenous rIL-9 inhibited tumor growth in Rag1(-/-) mice but not in mast-cell-deficient mice, suggesting that the targets of IL-9 in this setting include mast cells but not T or B cells. In addition, we found higher numbers of T(H)9 cells in normal human skin and blood compared to metastatic lesions of subjects with progressive stage IV melanoma. These results suggest a role for IL-9 in tumor immunity and offer insight into potential therapeutic strategies.

Antibody-Dependent Cellular Cytotoxicity-Mediating Antibodies from an HIV-1 Vaccine Efficacy Trial Target Multiple Epitopes and Preferentially Use the VH1 Gene Family

Abstract: The ALVAC-HIV/AIDSVAX-B/E RV144 vaccine trial showed an estimated efficacy of 31%. RV144 secondary immune correlate analysis demonstrated that the combination of low plasma anti-HIV-1 Env IgA antibodies and high levels of antibody-dependent cellular cytotoxicity (ADCC) inversely correlate with infection risk. One hypothesis is that the observed protection in RV144 is partially due to ADCC-mediating antibodies. We found that the majority (73 to 90%) of a representative group of vaccinees displayed plasma ADCC activity, usually (96.2%) blocked by competition with the C1 region-specific A32 Fab fragment. Using memory B-cell cultures and antigen-specific B-cell sorting, we isolated 23 ADCC-mediating nonclonally related antibodies from 6 vaccine recipients. These antibodies targeted A32-blockable conformational epitopes (n = 19), a non-A32-blockable conformational epitope (n = 1), and the gp120 Env variable loops (n = 3). Fourteen antibodies mediated cross-clade target cell killing. ADCC-mediating antibodies displayed modest levels of V-heavy (VH) chain somatic mutation (0.5 to 1.5%) and also displayed a disproportionate usage of VH1 family genes (74%), a phenomenon recently described for CD4-binding site broadly neutralizing antibodies (bNAbs). Maximal ADCC activity of VH1 antibodies correlated with mutation frequency. The polyclonality and low mutation frequency of these VH1 antibodies reveal fundamental differences in the regulation and maturation of these ADCC-mediating responses compared to VH1 bNAbs.

PD-1 blockade enhances T-cell migration to tumors by elevating IFN-γ inducible chemokines

Abstract: Adoptive cell transfer (ACT) is considered a promising modality for cancer treatment, but despite ongoing improvements, many patients do not experience clinical benefits. The tumor microenvironment is an important limiting factor in immunotherapy that has not been addressed fully in ACT treatments. In this study, we report that upregualtion of the immunosuppressive receptor programmed cell death-1 (PD-1) expressed on transferred T cells at the tumor site, in a murine model of ACT, compared with its expression on transferred T cells present in the peripheral blood and spleen. As PD-1 can attenuate T-cell-mediated antitumor responses, we tested whether its blockade with an anti-PD-1 antibody could enhance the antitumor activity of ACT in this model. Cotreatment with both agents increased the number of transferred T cells at the tumor site and also enhanced tumor regressions, compared with treatments with either agent alone. While anti-PD-1 did not reduce the number of immunosuppressive regulatory T cells and myeloid-derived suppressor cells present in tumor-bearing mice, we found that it increased expression of IFN-γ and CXCL10 at the tumor site. Bone marrow-transplant experiments using IFN-γR-/- mice implicated IFN-γ as a crucial nexus for controlling PD-1-mediated tumor infiltration by T cells. Taken together, our results imply that blocking the PD-1 pathway can increase IFN-γ at the tumor site, thereby increasing chemokine-dependent trafficking of immune cells into malignant disease sites.

Monoclonal antibodies in cancer therapy

Abstract: Monoclonal antibody-based treatment of cancer has been established as one of the most successful therapeutic strategies for both hematologic malignancies and solid tumors in the last 20 years. The initial combining of serological techniques for cancer cell surface antigen discovery with hybridoma technology led to a series of landmark clinical trials that paved the way for new generation antibodies and subsequent clinical success. Optimization of anti-tumor immune responses through Fc modifications has also made a major contribution to clinical efficacy. The modulation of immune system interplay with tumor cells through targeting of T cell receptors has emerged as a powerful new therapeutic strategy for tumor therapy and to enhance cancer vaccine efficacy. This commentary will provide an overview of the history of antibody identification of tumor surface antigens, antigenic targets suitable for antibody-based therapy, antibody mechanisms of action, and recent successes of antibodies in the clinic.

Potassium Channel KIR4.1 as an Immune Target in Multiple Sclerosis

Abstract: Background Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system. Many findings suggest that the disease has an autoimmune pathogenesis; the target of the immune response is not yet known. Methods We screened serum IgG from persons with multiple sclerosis to identify antibodies that are capable of binding to brain tissue and observed specific binding of IgG to glial cells in a subgroup of patients. Using a proteomic approach focusing on membrane proteins, we identified the ATP-sensitive inward rectifying potassium channel KIR4.1 as the target of the IgG antibodies. We used a multifaceted validation strategy to confirm KIR4.1 as a target of the autoantibody response in multiple sclerosis and to show its potential pathogenicity in vivo. Results Serum levels of antibodies to KIR4.1 were higher in persons with multiple sclerosis than in persons with other neurologic diseases and healthy donors (P<0.001 for both comparisons). We replicated this finding in two independent groups of persons with multiple sclerosis or other neurologic diseases (P<0.001 for both comparisons). Analysis of the combined data sets indicated the presence of serum antibodies to KIR4.1 in 186 of 397 persons with multiple sclerosis (46.9%), in 3 of 329 persons with other neurologic diseases (0.9%), and in none of the 59 healthy donors. These antibodies bound to the first extracellular loop of KIR4.1. Injection of KIR4.1 serum IgG into the cisternae magnae of mice led to a profound loss of KIR4.1 expression, altered expression of glial fibrillary acidic protein in astrocytes, and activation of the complement cascade at sites of KIR4.1 expression in the cerebellum. Conclusions KIR4.1 is a target of the autoantibody response in a subgroup of persons with multiple sclerosis. (Funded by the German Ministry for Education and Research and Deutsche Forschungsgemeinschaft.)

Follicular helper T cells in immunity and systemic autoimmunity

Abstract: Follicular helper T (T(FH)) cells are essential for B-cell maturation and immunoglobulin production after immunization with thymus-dependent antigens. Nevertheless, the development and function of T(FH) cells have been less clearly defined than classic CD4(+) effector T-cell subsets, including T-helper-1 (T(H)1), T(H)2 and T(H)17 cells. As such, our understanding of the genesis of T(FH) cells in humans and their role in the development of autoimmunity remains incomplete. However, evidence from animal models of systemic lupus erythematosus (SLE) and patients with systemic autoimmune diseases suggests that these cells are necessary for pathogenic autoantibody production, in a manner analogous to their role in promotion of B-cell maturation during normal immune responses. In this Review, I discuss the findings that have increased our knowledge of T(FH)-cell development and function in normal and aberrant immune responses. Such information might improve our understanding of autoimmune diseases, such as SLE, and highlights the potential of T(FH) cells as therapeutic targets in these diseases.

Evolution of an HIV glycan-dependent broadly neutralizing antibody epitope through immune escape

Abstract: Neutralizing antibodies are likely to play a crucial part in a preventative HIV-1 vaccine. Although efforts to elicit broadly cross-neutralizing (BCN) antibodies by vaccination have been unsuccessful, a minority of individuals naturally develop these antibodies after many years of infection. How such antibodies arise, and the role of viral evolution in shaping these responses, is unknown. Here we show, in two HIV-1-infected individuals who developed BCN antibodies targeting the glycan at Asn332 on the gp120 envelope, that this glycan was absent on the initial infecting virus. However, this BCN epitope evolved within 6 months, through immune escape from earlier strain-specific antibodies that resulted in a shift of a glycan to position 332. Both viruses that lacked the glycan at amino acid 332 were resistant to the Asn332-dependent BCN monoclonal antibody PGT128 (ref. 8), whereas escaped variants that acquired this glycan were sensitive. Analysis of large sequence and neutralization data sets showed the 332 glycan to be significantly under-represented in transmitted subtype C viruses compared to chronic viruses, with the absence of this glycan corresponding with resistance to PGT128. These findings highlight the dynamic interplay between early antibodies and viral escape in driving the evolution of conserved BCN antibody epitopes.

Protective Roles of Natural IgM Antibodies.

Abstract: Antibodies are a vital part of the armamentarium of the adaptive immune system for the fine-tuning of the recognition and response to foreign threats. However, in health there are some types of antibodies that instead recognize self-antigens and these contribute to the enhancement of primitive innate functions. This repertoire of natural IgM antibodies is postulated to have been selected during immune evolution for their contributions to critical immunoregulatory and housekeeping properties. The clearance of dying cells is one of the most essential responsibilities of the immune system, which is required to prevent uncontrolled inflammation and autoimmunity. In the murine immune system, natural IgM antibodies that recognize apoptotic cells have been shown to enhance the phagocytic clearance of dead and dying cells and to suppress innate immune signaling pathways. In the mouse, natural IgM are often the products of B-1 cell clones that arise during immune development without an absolute requirement for exogenous antigenic stimulation. In patients with systemic lupus erythematosus, IgM autoantibodies, which bind to neo-epitopes on apoptotic cells, have been demonstrated to be present at significantly higher levels in patients with lower disease activity and with less severe organ damage. While certain specificities of IgM autoantibodies correlate with protection from lupus renal disease, others may convey protective properties from lupus-associated atherosclerotic cardiovascular disease. New and unexpected insights into the functional roles of IgM antibodies are still emerging, especially regarding the functions of natural antibodies. Herein, we review recent progress in our understanding of the potential roles of natural IgM autoantibodies in the regulation of immune homeostasis and for protection from autoimmune and inflammatory diseases.

Monoclonal TCR-redirected tumor cell killing

Abstract: T cell immunity can potentially eradicate malignant cells and lead to clinical remission in a minority of patients with cancer. In the majority of these individuals, however, there is a failure of the specific T cell receptor (TCR)–mediated immune recognition and activation process. Here we describe the engineering and characterization of new reagents termed immune-mobilizing monoclonal TCRs against cancer (ImmTACs). Four such ImmTACs, each comprising a distinct tumor-associated epitope-specific monoclonal TCR with picomolar affinity fused to a humanized cluster of differentiation 3 (CD3)-specific single-chain antibody fragment (scFv), effectively redirected T cells to kill cancer cells expressing extremely low surface epitope densities. Furthermore, these reagents potently suppressed tumor growth in vivo. Thus, ImmTACs overcome immune tolerance to cancer and represent a new approach to tumor immunotherapy.

CMV drives clonal expansion of NKG2C+ NK cells expressing self-specific KIRs in chronic hepatitis patients.

Abstract: Natural killer (NK) cells are affected by infection with human cytomegalovirus (HCMV) manifested by increased expression of the HLA-E binding activating receptor NKG2C. We here show that HCMV seropositivity was associated with a profound expansion of NKG2C+CD56dim NK cells in patients with chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection. Multi-color flow cytometry revealed that the expanded NKG2C+CD56dim NK cells displayed a highly differentiated phenotype, expressed high amounts of granzyme B and exhibited polyfunctional responses (CD107a, IFN-γ, and TNF-α) to stimulation with antibody-coated as well as HLA-E expressing target cells but not when stimulated with IL-12/IL-18. More importantly, NKG2C+CD56dim NK cells had a clonal expression pattern of inhibitory killer cell immunoglobulin-like receptors (KIRs) specific for self-HLA class I molecules, with predominant usage of KIR2DL2/3. KIR engagement dampened NKG2C-mediated activation suggesting that such biased expression of self-specific KIRs may preserve self-tolerance and limit immune-pathology during viral infection. Together, these findings shed new light on how the human NK-cell compartment adjusts to HCMV infection resulting in clonal expansion and differentiation of educated and polyfunctional NK cells.

Aquaporin 4-Specific T Cells in Neuromyelitis Optica Exhibit a Th17 Bias and Recognize Clostridium ABC Transporter

Abstract: Neuromyelitis optica (NMO) is a rare, disabling, sometimes fatal, central nervous system (CNS) demyelinating disease characterized by severe attacks of optic neuritis and transverse myelitis.1 NMO is considered to be primarily a humoral autoimmune disease, as a majority of NMO patients develop autoantibodies (NMO immunoglobulin [Ig]G) against aquaporin 4 (AQP4),2 the predominant CNS water channel, which is abundantly expressed on astrocytes. AQP4-specific antibodies in NMO serum are IgG1, a subclass of mature IgG that requires help from T cells,3 indicating that AQP4-specific CD4+ T cells participate in the genesis of this adaptive humoral response. Passive transfer of AQP4-specific antibodies alone did not produce CNS pathology, but did promote development of NMO-like lesions in recipient animals when CNS inflammation was induced by myelin-specific T cells.4, 5 T cells are detected within active NMO lesions.6 Further, NMO lesions are characterized by an abundance of eosinophils and neutrophils, and elevated levels of IL-17 have been associated with NMO,7 suggesting involvement of Th17 cells. However, as no previous studies have identified or characterized proliferative AQP4-specific T cells in NMO patients, their potential role in NMO pathogenesis is largely unknown. In this report, we first identified peripheral blood T cells from NMO patients and healthy controls (HC) that proliferated in response to discrete AQP4 peptides or intact AQP4. T cells from NMO patients demonstrated greater proliferation to this autoantigen than those from HC, and responded most frequently to p61–80. After defining the p61–80 core T-cell determinant, residues 63–76, we conducted a homology search with known microbes. We discovered that AQP4 p63–76 contains strong homology to aa 204–217 of an adenosine triphosphate-binding cassette (ABC) transporter permease of Clostridium perfringens, a bacterial species that contains both commensal and pathogenic strains for humans. T cells from NMO patients responded to the homologous ABC transporter peptide and exhibited cross-reactivity between this foreign antigen and AQP4 p63–76, findings that support molecular mimicry. When compared to HC, AQP4 p61–80-specific T cells from NMO patients exhibited Th17 polarization. Monocytes from NMO patients produced significantly higher levels of the Th17-polarizing cytokine interleukin (IL)-6, suggesting that immunologic dysfunction in NMO may also include the innate immune compartment. Collectively, our findings establish that AQP4-specific proliferative T cells exist, and support a Th17 bias in the adaptive immune response in NMO. Our demonstration of T-cell molecular mimicry may stimulate further evaluation of the potential role of the Clostridium species in NMO pathogenesis.

Increased frequency of circulating follicular helper T cells in patients with rheumatoid arthritis.

Abstract: Follicular helper T (Tfh) cells are recognized as a distinct CD4(+) helper T-cell subset, which provides for B-cell activation and production of specific antibody responses, and play a critical role in the development of autoimmune disease. So far, only one study investigated the circulating Tfh cells increased in a subset of SLE patients. Since relatively little is known about the Tfh cells in rheumatoid arthritis (RA) patients, in this study, Tfh-cell frequency, related cytokine IL-21, and transcription factor Bcl-6 were investigated in 53 patients with RA and 31 health controls. Firstly, we found that the frequency of CD4(+)CXCR5(+)ICOS(high) Tfh cells was increased significantly in the peripheral blood of RA patients, compared with that in healthy controls. It is known that Tfh cells are critical for directing the development of an antibody response by germinal centers B cells; secondly, we observed that the Tfh-cell frequency is accompanied by the level of anti-CCP antibody in RA patients. Furthermore, expression of Bcl-6 mRNA and plasma IL-21 concentrations in RA patients was increased. Taken together, these findings have shown that the increased frequency of circulating Tfh cells is correlated with elevated levels of anti-CCP antibody, indicating the possible involvement of Tfh cells in the disease progression of RA.

Myositis-specific anti-155/140 autoantibodies target transcription intermediary factor 1 family proteins.

Abstract: Objective To identify the 140-kd autoantigen recognized by anti-155/140 autoantibodies that are associated with adult cancer-associated dermatomyositis (DM) and juvenile DM and to determine the clinical relevance of anti-155/140 antibodies in a large cohort. Methods Sera from 456 DM patients were assessed for the presence of anti-155/140 antibodies by immunoprecipitation using K562 cell extracts as substrate. Using immunoprecipitation and Western blotting, we then examined whether anti-155/140–positive sera recognized transcription intermediary factor 1α (TIF-1α), TIF-1β, and TIF-1γ. The clinical associations of antigen reactivity were also evaluated. Results Anti-155/140–positive sera reacted with 140-kd TIF-1α in addition to 155-kd TIF-1γ. Among sera from 456 DM patients, 52 were reactive with both TIF-1α and TIF-1γ, while another 25 were reactive with TIF-1γ alone. Additionally, 7 were reactive with TIF-1β. Malignancy was more frequently found in adult patients with both anti–TIF-1α and anti–TIF-1γ antibodies than in those with anti–TIF-1γ antibodies alone (73% versus 50%; P < 0.05). In addition to juvenile DM patients and middle-aged and older DM patients with high percentages of malignancy, 8 “young adult” DM patients without malignancy had these autoantibodies. Conclusion Anti-155/140 antibodies target TIF-1 family proteins, TIF-1α and TIF-1β, in addition to TIF-1γ. Since TIF-1 proteins have significant roles in oncogenesis, these antibodies may be produced during misdirected antitumor immunity.

Structural and genetic basis for development of broadly neutralizing influenza antibodies

Abstract: Influenza viruses take a yearly toll on human life despite efforts to contain them with seasonal vaccines. These viruses evade human immunity through the evolution of variants that resist neutralization. The identification of antibodies that recognize invariant structures on the influenza haemagglutinin (HA) protein have invigorated efforts to develop universal influenza vaccines. Specifically, antibodies to the highly conserved stem region of HA neutralize diverse viral subtypes. These antibodies largely derive from a specific antibody gene, heavy-chain variable region IGHV1-69, after limited affinity maturation from their germline ancestors, but how HA stimulates naive B cells to mature and induce protective immunity is unknown. To address this question, we analysed the structural and genetic basis for their engagement and maturation into broadly neutralizing antibodies. Here we show that the germline-encoded precursors of these antibodies act as functional B-cell antigen receptors (BCRs) that initiate subsequent affinity maturation. Neither the germline precursor of a prototypic antibody, CR6261 (ref. 3), nor those of two other natural human IGHV1-69 antibodies, bound HA as soluble immunoglobulin-G (IgG). However, all three IGHV1-69 precursors engaged HA when the antibody was expressed as cell surface IgM. HA triggered BCR-associated tyrosine kinase signalling by germline transmembrane IgM. Recognition and virus neutralization was dependent solely on the heavy chain, and affinity maturation of CR6261 required only seven amino acids in the complementarity-determining region (CDR) H1 and framework region 3 (FR3) to restore full activity. These findings provide insight into the initial events that lead to the generation of broadly neutralizing antibodies to influenza, informing the rational design of vaccines to elicit such antibodies and providing a model relevant to other infectious diseases, including human immunodeficiency virus/AIDS. The data further suggest that selected immunoglobulin genes recognize specific protein structural 'patterns' that provide a substrate for further affinity maturation.

Phase I Trial of Overlapping Long Peptides from a Tumor Self-Antigen and Poly-ICLC Shows Rapid Induction of Integrated Immune Response in Ovarian Cancer Patients

Abstract: Purpose: Long peptides are efficiently presented to both CD4 + and CD8 + T cells after intracellular processing by antigen-presenting cells. To investigate the safety and in vivo immunogenicity of synthetic overlapping long peptides (OLP) from a human tumor self-antigen, we conducted a phase I clinical trial with OLP from cancer-testis antigen NY-ESO-1 in various adjuvant combinations. Experimental Design: Twenty-eight patients with advanced ovarian cancer in second or third remission were enrolled sequentially in three cohorts and received at least one vaccination. Patients in Cohort 1 ( n = 4) received 1.0 mg OLP, Cohort 2 ( n = 13) received OLP in Montanide-ISA-51, and Cohort 3 ( n = 11) received OLP + 1.4 mg Poly-ICLC in Montanide-ISA-51 on weeks 1, 4, 7, 10, and 13. Humoral and cellular responses were evaluated by standardized immunomonitoring techniques (ELISA, ELISPOT assay, intracellular cytokine staining, and tetramer staining). Results: The vaccine was generally well tolerated with injection site reactions and fatigue that resolved. NY-ESO-1–specific antibody and CD8 + T cells were undetectable after vaccination with OLP alone, but were found in 6 of 13 (46%) and 8 of 13 (62%) patients, respectively, after vaccination with OLP+Montanide, and in 10 of 11 (91%) and 10 of 11 (91%) patients, respectively, after vaccination with OLP+Montanide+Poly-ICLC. NY-ESO-1–specific CD4 + T cells were detected in all patients with greater frequency and polyclonality when Montanide-ISA-51 was used for vaccination. Inclusion of Poly-ICLC as an adjuvant further accelerated the induction of NY-ESO-1–specific immune responses. Conclusions: The current study shows that NY-ESO-1 OLP vaccine is safe and rapidly induces consistent integrated immune responses (antibody, CD8 + and CD4 + ) in nearly all vaccinated patients when given with appropriate adjuvants. Clin Cancer Res; 18(23); 6497–508. ©2012 AACR .