Showing papers on "Antibody published in 2001"
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TL;DR: Fc gamma Rs offer a paradigm for the biological significance of balancing activation and inhibitory signaling in the expanding family of activation/inhibitory receptor pairs found in the immune system.
Abstract: Since the description of the first mouse knockout for an IgG Fc receptor seven years ago, considerable progress has been made in defining the in vivo functions of these receptors in diverse biological systems. The role of activating Fc gamma Rs in providing a critical link between ligands and effector cells in type II and type III inflammation is now well established and has led to a fundamental revision of the significance of these receptors in initiating cellular responses in host defense, in determining the efficacy of therapeutic antibodies, and in pathological autoimmune conditions. Considerable progress has been made in the last two years on the in vivo regulation of these responses, through the appreciation of the importance of balancing activation responses with inhibitory signaling. The inhibitory FcR functions in the maintenance of peripheral tolerance, in regulating the threshold of activation responses, and ultimately in terminating IgG mediated effector stimulation. The consequences of deleting the inhibitory arm of this system are thus manifested in both the afferent and efferent immune responses. The hyperresponsive state that results leads to greatly magnified effector responses by cytotoxic antibodies and immune complexes and can culminate in autoimmunity and autoimmune disease when modified by environmental or genetic factors. Fc gamma Rs offer a paradigm for the biological significance of balancing activation and inhibitory signaling in the expanding family of activation/inhibitory receptor pairs found in the immune system.
1,771 citations
TL;DR: Almost all of the key molecules involved in the innate and adaptive immune response are glycoproteins, and specific glycoforms are involved in recognition events.
Abstract: Almost all of the key molecules involved in the innate and adaptive immune response are glycoproteins. In the cellular immune system, specific glycoforms are involved in the folding, quality control, and assembly of peptide-loaded major histocompatibility complex (MHC) antigens and the T cell receptor complex. Although some glycopeptide antigens are presented by the MHC, the generation of peptide antigens from glycoproteins may require enzymatic removal of sugars before the protein can be cleaved. Oligosaccharides attached to glycoproteins in the junction between T cells and antigen-presenting cells help to orient binding faces, provide protease protection, and restrict nonspecific lateral protein-protein interactions. In the humoral immune system, all of the immunoglobulins and most of the complement components are glycosylated. Although a major function for sugars is to contribute to the stability of the proteins to which they are attached, specific glycoforms are involved in recognition events. For example, in rheumatoid arthritis, an autoimmune disease, agalactosylated glycoforms of aggregated immunoglobulin G may induce association with the mannose-binding lectin and contribute to the pathology.
1,474 citations
TL;DR: Although peripheral administration of m266 to PDAPP mice markedly reduces Aβ deposition, m266 did not bind to Aβ deposits in the brain, and m266 appears to reduce brain Aβ burden by altering CNS and plasma Aβ clearance.
Abstract: Active immunization with the amyloid beta (A beta) peptide has been shown to decrease brain A beta deposition in transgenic mouse models of Alzheimer's disease and certain peripherally administered anti-A beta antibodies were shown to mimic this effect. In exploring factors that alter A beta metabolism and clearance, we found that a monoclonal antibody (m266) directed against the central domain of A beta was able to bind and completely sequester plasma A beta. Peripheral administration of m266 to PDAPP transgenic mice, in which A beta is generated specifically within the central nervous system (CNS), results in a rapid 1,000-fold increase in plasma A beta, due, in part, to a change in A beta equilibrium between the CNS and plasma. Although peripheral administration of m266 to PDAPP mice markedly reduces A beta deposition, m266 did not bind to A beta deposits in the brain. Thus, m266 appears to reduce brain A beta burden by altering CNS and plasma A beta clearance.
1,361 citations
TL;DR: Clinical investigations in which the activity of TNF alpha in RA patients was blocked with intravenously administered infliximab, a chimeric anti-TNF alpha monoclonal antibody (mAB), has provided evidence that TNF regulates IL-6, IL-8, MCP-1, and VEGF production, recruitment of immune and inflammatory cells into joints, angiogenesis, and reduction of blood levels of matrix metalloproteinases-1 and -3.
Abstract: Rheumatoid arthritis (RA), a systemic disease, is characterized by a chronic inflammatory reaction in the synovium of joints and is associated with degeneration of cartilage and erosion of juxta-articular bone. Many pro-inflammatory cytokines including TNFα, chemokines, and growth factors are expressed in diseased joints. The rationale that TNFα played a central role in regulating these molecules, and their pathophysiological potential, was initially provided by the demonstration that anti-TNFα antibodies added to in vitro cultures of a representative population of cells derived from diseased joints inhibited the spontaneous production of IL-1 and other pro-inflammatory cytokines. Systemic administration of anti-TNFα antibody or sTNFR fusion protein to mouse models of RA was shown to be anti-inflammatory and joint protective. Clinical investigations in which the activcity of TNFα in RA patients was blocked with intravenously administered infliximab, a chimeric anti-TNFα monoclonal antibody (mAB), has prov...
1,300 citations
TL;DR: XBP-1 transcripts were rapidly upregulated in vitro by stimuli that induce plasma-cell differentiation, and were found at high levels in plasma cells from rheumatoid synovium, and when introduced into B-lineage cells, XBP- 1 initiated plasma- cell differentiation.
Abstract: Considerable progress has been made in identifying the transcription factors involved in the early specification of the B-lymphocyte lineage. However, little is known about factors that control the transition of mature activated B cells to antibody-secreting plasma cells. Here we report that the transcription factor XBP-1 is required for the generation of plasma cells. XBP-1 transcripts were rapidly upregulated in vitro by stimuli that induce plasma-cell differentiation, and were found at high levels in plasma cells from rheumatoid synovium. When introduced into B-lineage cells, XBP-1 initiated plasma-cell differentiation. Mouse lymphoid chimaeras deficient in XBP-1 possessed normal numbers of activated B lymphocytes that proliferated, secreted cytokines and formed normal germinal centres. However, they secreted very little immunoglobulin of any isotype and failed to control infection with the B-cell-dependent polyoma virus, because plasma cells were markedly absent. XBP-1 is the only transcription factor known to be selectively and specifically required for the terminal differentiation of B lymphocytes to plasma cells.
1,260 citations
TL;DR: Using genomic-scale gene expression profiling, CLL is characterized by a common gene expression “signature,” irrespective of Ig mutational status, suggesting that CLL cases share a common mechanism of transformation and/or cell of origin.
Abstract: The most common human leukemia is B cell chronic lymphocytic leukemia (CLL), a malignancy of mature B cells with a characteristic clinical presentation but a variable clinical course. The rearranged immunoglobulin (Ig) genes of CLL cells may be either germ-line in sequence or somatically mutated. Lack of Ig mutations defined a distinctly worse prognostic group of CLL patients raising the possibility that CLL comprises two distinct diseases. Using genomic-scale gene expression profiling, we show that CLL is characterized by a common gene expression “signature,” irrespective of Ig mutational status, suggesting that CLL cases share a common mechanism of transformation and/or cell of origin. Nonetheless, the expression of hundreds of other genes correlated with the Ig mutational status, including many genes that are modulated in expression during mitogenic B cell receptor signaling. These genes were used to build a CLL subtype predictor that may help in the clinical classification of patients with this disease.
1,158 citations
TL;DR: It is shown that mouse interferon-α–producing cells (mIPCs) are a unique subset of immature antigen-presenting cells (APCs) that secrete IFN-α upon stimulation with viruses and interleukin 12 (IL-12) in response to viruses and CpG oligodeoxynucleotides, but not bacterial products.
Abstract: We show here that mouse interferon-alpha (IFN-alpha)-producing cells (mIPCs) are a unique subset of immature antigen-presenting cells (APCs) that secrete IFN-alpha upon stimulation with viruses. mIPCs have a plasmacytoid morphology, can be stained with an antibody to Ly6G and Ly6C (anti-Ly6G/C) and are Ly6C+B220+CD11cloCD4+; unlike other dendritic cell subsets, however, they do not express CD8alpha or CD11b. Although mIPCs undergo apoptosis in vitro, stimulation with viruses, IFN-alpha or CpG oligonucleotides enhanced their survival and T cell stimulatory activity. In vivo, mIPCs were the main producers of IFN-alpha in cytomegalovirus-infected mice, as depletion of Ly6G+/C+ cells abrogated IFN-alpha production. mIPCs produced interleukin 12 (IL-12) in response to viruses and CpG oligodeoxynucleotides, but not bacterial products. Although different pathogens can selectively engage various APC subsets for IL-12 production, IFN-alpha production is restricted to mIPCs' response to viral infection.
1,056 citations
TL;DR: Protection was associated with the ability of IVIG administration to induce surface expression of FcgammaRIIB on splenic macrophages, and modulation of inhibitory signaling is a potent therapeutic strategy for attenuating autoantibody-triggered inflammatory diseases.
Abstract: The molecular basis for the anti-inflammatory property of intravenous gamma globulin (IVIG) was investigated in a murine model of immune thrombocytopenia. Administration of clinically protective doses of intact antibody or monomeric Fc fragments to wild-type or Fcgamma receptor-humanized mice prevented platelet consumption triggered by a pathogenic autoantibody. The inhibitory Fc receptor, FcgammaRIIB, was required for protection, because disruption either by genetic deletion or with a blocking monoclonal antibody reversed the therapeutic effect of IVIG. Protection was associated with the ability of IVIG administration to induce surface expression of FcgammaRIIB on splenic macrophages. Modulation of inhibitory signaling is thus a potent therapeutic strategy for attenuating autoantibody-triggered inflammatory diseases.
1,041 citations
TL;DR: Protein microarrays can provide a practical means to characterize patterns of variation in hundreds of thousands of different proteins in clinical or research applications, and are suggested to be sufficient for measurement of many clinically important proteins in patient blood samples.
Abstract: We describe a method for printing protein microarrays, and using these microarrays in a comparative fluorescence assay to measure the abundance of many specific proteins in complex solutions. A robotic device was used to print hundreds of specific antibody or antigen solutions in an array on the surface of derivatized microscope slides. Two complex protein samples, one serving as a standard for comparative quantitation, and the other representing an experimental sample in which the concentrations of specific proteins were to be measured, were labeled by covalent attachment of spectrally-resolvable fluorescent dyes. Specific antibody-antigen interactions localized specific components of the complex mixtures to defined cognate spots in the array, where the relative intensity of the fluorescent signals representing the experimental sample and the reference standard provided a measure of each protein's abundance in the experimental sample. To characterize the specificity, sensitivity and accuracy of this assay, we analyzed the performance of 115 antibody/antigen pairs. 50% of the arrayed antigens, and 20% of the arrayed antibodies, provided specific and accurate measurements of their cognate ligands at or below concentrations of 1.6 µg/ml and 0.34 µg/ml, respectively. Some of the antibody/antigen pairs allowed detection of the cognate ligands at absolute concentrations below 1 ng/ml, and partial concentrations of less than 1 part in 106, sensitivities sufficient for measurement of many clinically important proteins in patient blood samples. Protein microarrays can provide a simple and practical means to characterize patterns of variation in hundreds or thousands of different proteins, in clinical or research applications.
939 citations
TL;DR: The results suggest that a rather extensive region of gp41 close to the transmembrane domain is accessible to neutralizing Abs and could form a useful target for vaccine design.
Abstract: The identification and epitope mapping of broadly neutralizing anti-human immunodeficiency virus type 1 (HIV-1) antibodies (Abs) is important for vaccine design, but, despite much effort, very few such Abs have been forthcoming. Only one broadly neutralizing anti-gp41 monoclonal Ab (MAb), 2F5, has been described. Here we report on two MAbs that recognize a region immediately C-terminal of the 2F5 epitope. Both MAbs were generated from HIV-1-seropositive donors, one (Z13) from an antibody phage display library, and one (4E10) as a hybridoma. Both MAbs recognize a predominantly linear and relatively conserved epitope, compete with each other for binding to synthetic peptide derived from gp41, and bind to HIV-1(MN) virions. By flow cytometry, these MAbs appear to bind relatively weakly to infected cells and this binding is not perturbed by pretreatment of the infected cells with soluble CD4. Despite the apparent linear nature of the epitopes of Z13 and 4E10, denaturation of recombinant envelope protein reduces the binding of these MAbs, suggesting some conformational requirements for full epitope expression. Most significantly, Z13 and 4E10 are able to neutralize selected primary isolates from diverse subtypes of HIV-1 (e.g., subtypes B, C, and E). The results suggest that a rather extensive region of gp41 close to the transmembrane domain is accessible to neutralizing Abs and could form a useful target for vaccine design.
855 citations
Patent•
30 Nov 2001TL;DR: In this article, a transgenic nonhuman mammal capable of producing human sequence antibodies was presented. But the method of producing and using these antibodies was not described. But it was shown that these antibodies can be used for medical applications.
Abstract: The present invention provides novel transgenic nonhuman mammals capable of producing human sequence antibodies, as well as methods of producing and using these antibodies.
TL;DR: It is shown that passive intravenous transfer of the human neutralizing monoclonal antibody b12 provides dose-dependent protection to macaques vaginally challenged with the R5 virus SHIV162P4, suggesting that a vaccine based on antibody alone would need to sustain serum neutralizing antibody titers of the order of 1:400 to achieve sterile protection but that lower titers, around 1:100, could provide a significant benefit.
Abstract: A major unknown in human immunodeficiency virus (HIV-1) vaccine design is the efficacy of antibodies in preventing mucosal transmission of R5 viruses. These viruses, which use CCR5 as a coreceptor, appear to have a selective advantage in transmission of HIV-1 in humans. Hence R5 viruses predominate during primary infection and persist throughout the course of disease in most infected people. Vaginal challenge of macaques with chimeric simian/human immunodeficiency viruses (SHIV) is perhaps one of the best available animal models for human HIV-1 infection. Passive transfer studies are widely used to establish the conditions for antibody protection against viral challenge. Here we show that passive intravenous transfer of the human neutralizing monoclonal antibody b12 provides dose-dependent protection to macaques vaginally challenged with the R5 virus SHIV(162P4). Four of four monkeys given 25 mg of b12 per kg of body weight 6 h prior to challenge showed no evidence of viral infection (sterile protection). Two of four monkeys given 5 mg of b12/kg were similarly protected, whereas the other two showed significantly reduced and delayed plasma viremia compared to control animals. In contrast, all four monkeys treated with a dose of 1 mg/kg became infected with viremia levels close to those for control animals. Antibody b12 serum concentrations at the time of virus challenge corresponded to approximately 400 (25 mg/kg), 80 (5 mg/kg), and 16 (1 mg/kg) times the in vitro (90%) neutralization titers. Therefore, complete protection against mucosal challenge with an R5 SHIV required essentially complete neutralization of the infecting virus. This suggests that a vaccine based on antibody alone would need to sustain serum neutralizing antibody titers (90%) of the order of 1:400 to achieve sterile protection but that lower titers, around 1:100, could provide a significant benefit. The significance of such substerilizing neutralizing antibody titers in the context of a potent cellular immune response is an important area for further study.
TL;DR: It is suggested that BLyS is required for the development of most but not all mature B cell populations found in the periphery, while B-1 cell numbers are relatively normal inBLyS-deficient mice.
TL;DR: Serum specimens from 46 women with preconceptional immunity against CMV that were obtained during the previous pregnancy and the current pregnancy were analyzed for antibodies against the strain-specific epitopes of CMV glycoprotein H.
Abstract: Background Preconceptional immunity against cytomegalovirus (CMV) provides only partial protection against intrauterine transmission of the virus. Whether congenital CMV infection in the offspring of women who are seropositive for CMV can occur after maternal reinfection with a different strain of CMV is unknown. Methods Serum specimens from 46 women with preconceptional immunity against CMV that were obtained during the previous pregnancy and the current pregnancy were analyzed for antibodies against the strain-specific epitopes of CMV glycoprotein H. Virus-neutralizing activity in maternal serum samples was measured against the AD169 laboratory strain of CMV and the CMV isolates available from seven infected infants. In addition, the nucleotide sequences of the glycoprotein H gene from the seven CMV isolates were determined. Results Eleven of the 16 mothers with infected infants (69 percent) had antibodies against the glycoprotein H epitopes present on two laboratory strains of CMV, AD169 and Towne. Ten...
Patent•
05 Oct 2001TL;DR: In this article, a cell for the production of an antibody molecule such as an antibody useful for various diseases having high antibody-dependent cell-mediated cytotoxic activity, a fragment of the antibody and a fusion protein having the Fc region of the anti-antibody or the like.
Abstract: The present invention relates to a cell for the production of an antibody molecule such as an antibody useful for various diseases having high antibody-dependent cell-mediated cytotoxic activity, a fragment of the antibody and a fusion protein having the Fc region of the antibody or the like, a process for producing an antibody composition using the cell, the antibody composition and use thereof.
TL;DR: Data demonstrate a new mechanism for thrombocytopenia in which antibody develops to TPO; because endogenous TPO is produced constitutively, throm bocy topenia ensues.
TL;DR: It is shown here that elevated levels of cell-surface expression of DR5 and increased susceptibility to DR5-mediated apoptosis are characteristics of malignant tumor cells and selective, specific targeting ofDR5 with an agonistic antibody might be a safe and effective strategy for cancer therapy.
Abstract: A novel anti-human DR5 monoclonal antibody, TRA-8, induces apoptosis of most tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-sensitive tumor cells both in vitro and in vivo. In contrast to both the membrane-bound form of human TRAIL, which induced severe hepatitis in mice, and the soluble form of human TRAIL, which induced apoptosis of normal human hepatocytes in vitro, TRA-8 did not induce significant cell death of normal human hepatocytes. However, both primary hepatocellular carcinoma cells and an established liver cancer cell line were highly susceptible to the killing mediated by TRA-8. We show here that elevated levels of cell-surface expression of DR5 and increased susceptibility to DR5-mediated apoptosis are characteristics of malignant tumor cells. In contrast, DR5 alone is not sufficient to trigger apoptosis of normal hepatocytes. Therefore, selective, specific targeting of DR5 with an agonistic antibody might be a safe and effective strategy for cancer therapy.
TL;DR: In this article, a preclinical and human vaccine studies indicate that, although neonatal immunisation does not generally lead to rapid and strong antibody responses, it may result in an efficient immunological priming, which can serve as an excellent basis for future responses.
TL;DR: B cells can regulate many aspects of immune reactivity, as well as differentiate into antibody-producing cells, and in SLE, recent research suggests enhanced B cell function is the defining pathogenic event.
Abstract: B cells can regulate many aspects of immune reactivity, as well as differentiate into antibody-producing cells. In SLE, a systemic autoimmune disease, recent research suggests enhanced B cell function is the defining pathogenic event.
TL;DR: The results indicate that most MAbs that neutralize virus infectivity do so, at least in part, by the blocking of virus adsorption, and provide the first direct evidence that domain III encodes the primary flavivirus receptor-binding motif.
Abstract: The specific mechanisms by which antibodies neutralize flavivirus infectivity are not completely understood. To study these mechanisms in more detail, we analyzed the ability of a well-defined set of anti-dengue (DEN) virus E-glycoprotein-specific monoclonal antibodies (MAbs) to block virus adsorption to Vero cells. In contrast to previous studies, the binding sites of these MAbs were localized to one of three structural domains (I, II, and III) in the E glycoprotein. The results indicate that most MAbs that neutralize virus infectivity do so, at least in part, by the blocking of virus adsorption. However, MAbs specific for domain III were the strongest blockers of virus adsorption. These results extend our understanding of the structure-function relationships in the E glycoprotein of DEN virus and provide the first direct evidence that domain III encodes the primary flavivirus receptor-binding motif.
TL;DR: 4E10 neutralizes potently not only tissue culture-adapted strains but also primary isolates of different clades, including A, B, C, D, and E, confirming that the region recognized by 2F5 and 4E10 is essential for viral infectivity and may be important for vaccine design.
Abstract: We have established a panel of human monoclonal antibodies against human immunodeficiency virus type 1 (HIV-1). The antibodies 2F5 and 2G12 have been identified to be two of the most potently in vitro neutralizing antibodies against HIV-1. Here we report on a further antibody, 4E10, of similar in vitro neutralizing potency. 4E10 binds to a novel epitope C terminal of the ELDKWA sequence recognized by 2F5, which has been so far the only described broadly neutralizing anti-gp41 antibody. Both 4E10 and 2F5 bind only weakly to infected cells compared with gp120-specific 2G12 and polyclonal anti-HIV-1 immunoglobulin (HIVIG), but show potent in vitro neutralizing properties. 4E10 neutralizes potently not only tissue culture-adapted strains but also primary isolates of different clades, including A, B, C, D, and E. Viruses that were found to be resistant to 2F5 were neutralized by 4E10 and vice versa; none of the tested isolates was resistant to both anti-gp41 antibodies. This confirms that the region recognized...
Patent•
16 Oct 2001TL;DR: In this paper, proteins that include an immunoglobulin fold and that can be used as scaffolds are described, and nucleic acids encoding such proteins and the use of such proteins in diagnostic methods and in methods for evolving novel compound-binding species and their ligands.
Abstract: Disclosed herein are proteins that include an immunoglobulin fold and that can be used as scaffolds. Also disclosed herein are nucleic acids encoding such proteins and the use of such proteins in diagnostic methods and in methods for evolving novel compound-binding species and their ligands.
TL;DR: The gene encoding the rat glycosylation enzyme beta1-4-N-acetylglucosaminyltransferase III (GnTIII) was cloned and coexpressed in a recombinant production Chinese hamster ovary cell line expressing a chimeric mouse/human anti-CD20 IgG1 antibody.
Abstract: The gene encoding the rat glycosylation enzyme beta1-4-N-acetylglucosaminyltransferase III (GnTIII) was cloned and coexpressed in a recombinant production Chinese hamster ovary (CHO) cell line expressing a chimeric mouse/human anti-CD20 IgG1 antibody. The new cell lines expressed high levels of antibody and have growth kinetics similar to that of the parent. Relative QPCR showed the cell lines to express varying levels of mRNA. High-performance liquid chromatography (HPLC) analysis showed the enzyme to have added bisecting N-acetylglucosamine (GlcNAc) residues in most (48% to 71%) of the N-linked oligosaccharides isolated from antibody preparations purified from the cell lines. In an ADCC assay the new antibody preparations promoted killing of CD20-positive target cells at approximately 10- to 20-fold lower concentrations than the parent. This activity was blocked using an anti-Fc gamma RIII antibody, supporting the role of Fc gamma RIII binding in this increase. In addition, cell binding assays showed the modified antibody bound better to Fc gamma RIII-expressing cells. The increase in ADCC activity is therefore likely due to an increased affinity of the modified antibody for the Fc gamma RIII receptor.
Book•
27 Apr 2001
TL;DR: This book discusses Immunity, the Nomenclature, General Properties, and Components of the Immune System, and the Development of Immune Repertoires.
Abstract: Chapter 1: Introduction to the Immune System The Nomenclature, General Properties, and Components of the Immune System Chapter 2: Innate Immunity The Early Defense Against Infections Chapter 3: Antigen Capture and Presentation to Lymphocytes What Lymphocytes See Chapter 4: Antigen Recognition in the Adaptive Immune System Structure of Lymphocyte Antigen Receptors and the Development of Immune Repertoires Chapter 5: Cell-Mediated Immune Responses Activation of T Lymphocytes by Cell-Associated Microbes Chapter 6: Effector Mechanisms of Cell-Mediated Immunity Eradication of Intracellular Microbes Chapter 7: Humoral Immune Responses Activation of B Lymphocytes and Production of Antibodies Chapter 8: Effector Mechanisms of Humoral Immunity The Elimination of Extracellular Microbes and Toxins Chapter 9: Immunologic Tolerance and Autoimmunity Self-Nonself Discrimination in the Immune System and Its Failure Chapter 10: Immune Responses Against Tumors and Transplants Immunity to Noninfectious Transformed and Foreign Cells Chapter 11: Hypersensitivity Diseases Disorders Caused by Immune Responses Chapter 12: Congenital and Acquired Immunodeficiencies Diseases Caused by Defective Immune Responses Suggested Readings Appendix I: Principal Features of CD Molecules Appendix II: Glossary Appendix III: Clinical Cases Index
TL;DR: Evidence is provided that adhesins such as HBHA are required for extrapulmonary dissemination, and that interactions with non-phagocytic cells have an important role in the pathogenesis of tuberculosis.
Abstract: Tuberculosis remains the world's leading cause of death due to a single infectious agent, Mycobacterium tuberculosis, with 3 million deaths and 10 million new cases per year1. The infection initiates in the lungs and can then spread rapidly to other tissues2. The availability of the entire M. tuberculosis genome sequence3 and advances in gene disruption technologies4 have led to the identification of several mycobacterial determinants involved in virulence5,6,7,8. However, no virulence factor specifically involved in the extrapulmonary dissemination of M. tuberculosis has been identified to date. Here we show that the disruption of the M. tuberculosis or Mycobacterium bovis Bacille Calmette–Guerin (BCG) hbhA gene encoding the heparin-binding haemagglutinin adhesin (HBHA) markedly affects mycobacterial interactions with epithelial cells, but not with macrophage-like cells. When nasally administered to mice, the mutant strains were severely impaired in spleen colonization, but not in lung colonization. Coating wild-type mycobacteria with anti-HBHA antibodies also impaired dissemination after intranasal infection. These results provide evidence that adhesins such as HBHA are required for extrapulmonary dissemination, and that interactions with non-phagocytic cells have an important role in the pathogenesis of tuberculosis. They also suggest that antibody responses to HBHA may add to immune protection against tuberculosis.
TL;DR: It is concluded that IgA+ cells in the gut lamina propria are generated in situ from B220+IgM+ lymphocytes, as they still express both AID and transcripts from circular DNA that has been ‘looped-out' during CSR.
Abstract: One of the front lines of the immune defence is the gut mucosa, where immunoglobulin- (IgA) is continuously produced to react with commensal bacteria and dietary antigens. It is generally accepted that, after antigenic stimulation in the Peyer's patches, IgA+ lymphoblasts (B220+IgA+) migrate through the lymph and blood circulation, and eventually home to the lamina propria of the intestine. Mice that lack activation-induced cytidine deaminase (AID) are defective in class switch recombination (CSR) and somatic hypermutation. CSR changes the immunoglobulin heavy chain constant region (CH) gene being expressed from Cmu to other CH genes, resulting in a switch of the immunoglobulin isotype from IgM to IgG, IgE or IgA. AID-/- mice also secrete large amounts of immunoglobulin-mu (IgM) into faeces, and accumulate B220-IgM+ plasma cells as well as B220+IgM+ cells in the gut. Here we show that lamina propria B220+IgA+ cells have just completed CSR, as they still express both AID and transcripts from circular DNA that has been 'looped-out' during CSR. Lamina propria IgM+ B cells seem to be pre-committed to switching to IgA+ in vitro as well as in vivo. Culturing lamina propria IgM+ B cells together with lamina propria stromal cells enhances preferential switching and differentiation of B cells to IgA+ plasma cells. We conclude that IgA+ cells in the gut lamina propria are generated in situ from B220+IgM+ lymphocytes.
TL;DR: This work presents the first evidence that control of a virus infection in vivo is mediated by a distinct NK cell subset, as well as some redistributions of NK cell subsets defined by monoclonal antibody directed against Ly49A, C/I, D, and G2.
Abstract: Antiviral roles of natural killer (NK) cell subsets were examined in C57BL/6 mice infected with murine cytomegalovirus (MCMV) and other viruses, including lymphocytic choriomeningitis virus (LCMV), vaccinia virus (VV), and mouse hepatitis virus (MHV). Each virus vigorously induced an NK cell infiltrate into the peritoneal cavity and liver, causing some redistributions of NK cell subsets defined by monoclonal antibody (mAb) directed against Ly49A, C/I, D, and G2. Striking results were seen with a mAb (1F8) reactive with the positively signaling molecule Ly49H, present in MCMV-resistant C57BL/6 mice. mAb 1F8 also stains Ly49 C and I, but exclusion of those reactivities with mAb 5E6, which recognizes Ly49 C and I, indicated that Ly49H(+) cells infiltrated the peritoneal cavity and liver and were particularly effective at synthesizing interferon gamma. Depletion of 1F8(+) but not 5E6(+) cells in vivo by mAb injections enhanced MCMV titers by 20-1,000-fold in the spleen and approximately fivefold in the liver. Titers of LCMV or VV were not enhanced. These anti-MCMV effects were attributed to prototypical NK1.1(+)CD3(-) NK cells and not to NK1.1(+)CD3(+) "NK/T" cells. This is the first evidence that control of a virus infection in vivo is mediated by a distinct NK cell subset.
TL;DR: It is confirmed that K322 forms part of the C1q binding site in human IgG1 and plays an important role in the molecular interactions leading to complement activation, and it is demonstrated that the lower hinge region in human igG1 has a strong modulating effect on C 1q binding and CDC.
Abstract: The human antibody immunoglobulin G1 (IgG1) b12 neutralizes a broad range of human immunodeficiency virus-type 1 (HIV-1) isolates in vitro and is able to protect against viral challenge in animal models Neutralization of free virus, which is an antiviral activity of antibody that generally does not require the antibody Fc fragment, likely plays an important role in the protection observed The role of Fc-mediated effector functions, which may reduce infection by inducing phagocytosis and lysis of virions and infected cells, however, is less clear To investigate this role, we constructed a panel of IgG1 b12 mutants with point mutations in the second domain of the antibody heavy chain constant region (CH2) These mutations, as expected, did not affect gp120 binding or HIV-1 neutralization IgG1 b12 mediated strong antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) of HIV-1-infected cells, but these activities were reduced or abrogated for the antibody mutants Two mutants were of particular interest K322A showed a twofold reduction in FcγR binding affinity and ADCC, while C1q binding and CDC were abolished A double mutant (L234A, L235A) did not bind either FcγR or C1q, and both ADCC and CDC functions were abolished In this study, we confirmed that K322 forms part of the C1q binding site in human IgG1 and plays an important role in the molecular interactions leading to complement activation Less expectedly, we demonstrate that the lower hinge region in human IgG1 has a strong modulating effect on C1q binding and CDC The b12 mutants K322A and L234A, L235A are useful tools for dissecting the in vivo roles of ADCC and CDC in the anti-HIV-1 activity of neutralizing antibodies
Journal Article•
TL;DR: It is concluded that systemic antagonization of VEGFR-2 can inhibit glioblastoma neovascularization and growth but can lead to increased cooption of preexistent cerebral blood vessels, and a combination of different treatment modalities which also include anti-invasive therapy may be needed for an effective therapy against gliOBlastoma.
Abstract: Using an orthotopic intracerebral model, we investigated whether systemic treatment with DC101, a monoclonal antibody against vascular endothelial growth factor receptor (VEGFR)-2, could inhibit angiogenesis and the growth of human glioblastoma cells in severe combined immunodeficient mice. Intraperitoneal treatment with DC101, control IgG, or PBS was initiated either on day 0 or, in another series, on day 6 after tumor cell implantation, and animals were killed approximately 2 weeks after tumor cell injection. Tumor volumes in animals treated with DC101 were reduced by 59 and 81% compared with IgG and PBS controls, respectively (P < 0.001), when treatment was initiated immediately, and similar results were obtained when treatment started on day 6. Microvessel density in tumors of DC101-treated animals was reduced by at least 40% compared with animals treated with control IgG or PBS (P < 0.01). We observed a reduction in tumor cell proliferation and an increase in apoptosis in DC101-treated animals (P < 0.001). However, in mice treated with DC101, we also noticed a striking increase in the number and total area of small satellite tumors clustered around, but distinct from, the primary. These satellites usually contained central vessel cores, and tumor cells often had migrated over long distances along the host vasculature to eventually reach the surface and spread leptomeningeally. We conclude that systemic antagonization of VEGFR-2 can inhibit glioblastoma neovascularization and growth but can lead to increased cooption of preexistent cerebral blood vessels. Therefore, a combination of different treatment modalities which also include anti-invasive therapy may be needed for an effective therapy against glioblastoma, and the use of an antibody against VEGFR-2 may be one effective component.
TL;DR: In this paper, 30 patients with chronic active Epstein-Barr virus (CAEBV) infection were analyzed, and they were divided into two clinically distinct groups, based on whether the predominantly infected cells in their peripheral blood were T cells or natural killer (NK) cells.