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Khoy K, Mariotte D, Defer G, Petit G, Toutirais O, Le Mauff B. Natalizumab in Multiple Sclerosis Treatment: From Biological Effects to Immune Monitoring. Front Immunol 2020; 11:549842. [PMID: 33072089 PMCID: PMC7541830 DOI: 10.3389/fimmu.2020.549842] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 09/04/2020] [Indexed: 12/13/2022] Open
Abstract
Multiple sclerosis is a chronic demyelinating disease of the central nervous system (CNS) with an autoimmune component. Among the recent disease-modifying treatments available, Natalizumab, a monoclonal antibody directed against the alpha chain of the VLA-4 integrin (CD49d), is a potent inhibitor of cell migration toward the tissues including CNS. It potently reduces relapses and active brain lesions in the relapsing remitting form of the disease. However, it has also been associated with a severe infectious complication, the progressive multifocal leukoencephalitis (PML). Using the standard protocol with an injection every 4 weeks it has been shown by a close monitoring of the drug that trough levels soon reach a plateau with an almost saturation of the target cell receptor as well as a down modulation of this receptor. In this review, mechanisms of action involved in therapeutic efficacy as well as in PML risk will be discussed. Furthermore the interest of a biological monitoring that may be helpful to rapidly adapt treatment is presented. Indeed, development of anti-NAT antibodies, although sometimes unapparent, can be detected indirectly by normalization of CD49d expression on circulating mononuclear cells and might require to switch to another drug. On the other hand a stable modulation of CD49d expression might be useful to follow the circulating NAT levels and apply an extended interval dose scheme that could contribute to limiting the risk of PML.
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Affiliation(s)
- Kathy Khoy
- Laboratory of Immunology, Department of Biology, CHU Caen Normandie, Caen, France
| | - Delphine Mariotte
- Laboratory of Immunology, Department of Biology, CHU Caen Normandie, Caen, France
| | - Gilles Defer
- Department of Neurology, MS Expert Centre, CHU Caen Normandie, Caen, France.,UMR-S1237, Physiopathology and Imaging of Neurological Disorders, INSERM, Caen, France.,Normandie Université, UNICAEN, Caen, France
| | - Gautier Petit
- Laboratory of Immunology, Department of Biology, CHU Caen Normandie, Caen, France
| | - Olivier Toutirais
- Laboratory of Immunology, Department of Biology, CHU Caen Normandie, Caen, France.,UMR-S1237, Physiopathology and Imaging of Neurological Disorders, INSERM, Caen, France.,Normandie Université, UNICAEN, Caen, France
| | - Brigitte Le Mauff
- Laboratory of Immunology, Department of Biology, CHU Caen Normandie, Caen, France.,UMR-S1237, Physiopathology and Imaging of Neurological Disorders, INSERM, Caen, France.,Normandie Université, UNICAEN, Caen, France
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2
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De Groot AS, Moise L, Terry F, Gutierrez AH, Hindocha P, Richard G, Hoft DF, Ross TM, Noe AR, Takahashi Y, Kotraiah V, Silk SE, Nielsen CM, Minassian AM, Ashfield R, Ardito M, Draper SJ, Martin WD. Better Epitope Discovery, Precision Immune Engineering, and Accelerated Vaccine Design Using Immunoinformatics Tools. Front Immunol 2020; 11:442. [PMID: 32318055 PMCID: PMC7154102 DOI: 10.3389/fimmu.2020.00442] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 02/26/2020] [Indexed: 12/19/2022] Open
Abstract
Computational vaccinology includes epitope mapping, antigen selection, and immunogen design using computational tools. Tools that facilitate the in silico prediction of immune response to biothreats, emerging infectious diseases, and cancers can accelerate the design of novel and next generation vaccines and their delivery to the clinic. Over the past 20 years, vaccinologists, bioinformatics experts, and advanced programmers based in Providence, Rhode Island, USA have advanced the development of an integrated toolkit for vaccine design called iVAX, that is secure and user-accessible by internet. This integrated set of immunoinformatic tools comprises algorithms for scoring and triaging candidate antigens, selecting immunogenic and conserved T cell epitopes, re-engineering or eliminating regulatory T cell epitopes, and re-designing antigens to induce immunogenicity and protection against disease for humans and livestock. Commercial and academic applications of iVAX have included identifying immunogenic T cell epitopes in the development of a T-cell based human multi-epitope Q fever vaccine, designing novel influenza vaccines, identifying cross-conserved T cell epitopes for a malaria vaccine, and analyzing immune responses in clinical vaccine studies. Animal vaccine applications to date have included viral infections of pigs such as swine influenza A, PCV2, and African Swine Fever. “Rapid-Fire” applications for biodefense have included a demonstration project for Lassa Fever and Q fever. As recent infectious disease outbreaks underscore the significance of vaccine-driven preparedness, the integrated set of tools available on the iVAX toolkit stand ready to help vaccine developers deliver genome-derived, epitope-driven vaccines.
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Affiliation(s)
- Anne S De Groot
- EpiVax, Inc., Providence, RI, United States.,Institute for Immunology and Informatics, Providence, RI, United States
| | - Leonard Moise
- EpiVax, Inc., Providence, RI, United States.,Institute for Immunology and Informatics, Providence, RI, United States
| | | | - Andres H Gutierrez
- EpiVax, Inc., Providence, RI, United States.,Institute for Immunology and Informatics, Providence, RI, United States
| | | | | | - Daniel Fredric Hoft
- Departments of Molecular Microbiology & Immunology and Internal Medicine, Division of Infectious Diseases, Allergy & Immunology, Saint Louis University, St. Louis, MO, United States
| | - Ted M Ross
- Center for Vaccines and Immunology, University of Georgia, Athens, GA, United States
| | - Amy R Noe
- Leidos Life Sciences, Frederick, MD, United States
| | | | | | - Sarah E Silk
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | | | | | | | | | - Simon J Draper
- Jenner Institute, University of Oxford, Oxford, United Kingdom
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3
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A High-Throughput Single-Clone Phage Fluorescence Microwell Immunoassay and Laser-Driven Clonal Retrieval System. Biomolecules 2020; 10:biom10040517. [PMID: 32235304 PMCID: PMC7226094 DOI: 10.3390/biom10040517] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 03/26/2020] [Indexed: 12/03/2022] Open
Abstract
Phage display is one of the most frequently used platform technologies utilized to screen and select therapeutic antibodies, and has contributed to the development of more than 10 therapeutic antibodies used in the clinic. Despite advantages like efficiency and low cost, it has intrinsic technical limitations, such as the asymmetrical amplification of the library after each round of biopanning, which is regarded as a reason for it yielding a very limited number of antigen binders. In this study, we developed a high-throughput single-clonal screening system comprised of fluorescence immunoassays and a laser-driven clonal DNA retrieval system using microchip technology. Using this system, from a single-chain variable fragment (scFv) library displayed on phages with a complexity of 5.21 × 105 harboring random mutations at five amino acid residues, more than 70,000 clones—corresponding to ~14% of the library complexity—were screened, resulting in 78 antigen-reactive scFv sequences with mutations restricted to the randomized residues. Our results demonstrate that this system can significantly reduce the number of biopanning rounds, or even eliminate the need for this process for libraries with lower complexity, providing an opportunity to obtain more diverse clones from the library.
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4
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Faraji F, Karjoo Z, Moghaddam MV, Heidari S, Emameh RZ, Falak R. Challenges related to the immunogenicity of parenteral recombinant proteins: Underlying mechanisms and new approaches to overcome it. Int Rev Immunol 2018; 37:301-315. [PMID: 29851534 DOI: 10.1080/08830185.2018.1471139] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Immune response elicited by therapeutic proteins is an important safety and efficacy issue for regulatory agencies, drug manufacturers, clinicians, and patients. Administration of therapeutic proteins can potentially induce the production of anti-drug antibodies or cell-mediated immune responses. At first, it was speculated that the immunogenicity is related to the non-human origin of these proteins. Later on, it was confirmed that the human proteins may also show immunogenicity. In this review article, we will focus on a number of factors, which play crucial roles in the human protein immunogenicity. These factors are related to the patient's status (or intrinsic properties) and molecular characteristics of the therapeutic protein's (or extrinsic properties). Furthermore, we will discuss available in silico, in vitro, and in vivo methods for the prediction of sequences, which may generate an immune response following parenteral administration of these proteins. In summary, nowadays, it is possible for drug manufacturers to evaluate the risk of immunogenicity of therapeutic proteins and implement a management plan to overcome the problems prior to proceeding to human clinical trials.
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Affiliation(s)
- Fatemeh Faraji
- a Immunology Research Center , Iran University of Medical Sciences (IUMS) , Tehran , Iran.,b Department of Immunology, School of Medicine , Iran University of Medical Sciences (IUMS) , Tehran , Iran
| | - Zahra Karjoo
- a Immunology Research Center , Iran University of Medical Sciences (IUMS) , Tehran , Iran
| | | | - Sahel Heidari
- a Immunology Research Center , Iran University of Medical Sciences (IUMS) , Tehran , Iran.,b Department of Immunology, School of Medicine , Iran University of Medical Sciences (IUMS) , Tehran , Iran
| | - Reza Zolfaghari Emameh
- c Department of Energy and Environmental Biotechnology, Division of Industrial & Environmental Biotechnology , National Institute of Genetic Engineering and Biotechnology (NIGEB) , Tehran , Iran
| | - Reza Falak
- a Immunology Research Center , Iran University of Medical Sciences (IUMS) , Tehran , Iran.,b Department of Immunology, School of Medicine , Iran University of Medical Sciences (IUMS) , Tehran , Iran
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5
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Asgari S, Mirzahoseini H, Karimipour M, Rahimi H, Ebrahim-Habibi A. Rational design of stable and functional hirudin III mutants with lower antigenicity. Biologicals 2015; 43:479-91. [DOI: 10.1016/j.biologicals.2015.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 07/12/2015] [Accepted: 07/23/2015] [Indexed: 12/25/2022] Open
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He L, De Groot AS, Bailey-Kellogg C. Hit-and-run, hit-and-stay, and commensal bacteria present different peptide content when viewed from the perspective of the T cell. Vaccine 2015; 33:6922-9. [PMID: 26428457 DOI: 10.1016/j.vaccine.2015.08.099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 08/10/2015] [Accepted: 08/24/2015] [Indexed: 01/02/2023]
Abstract
Different types of bacteria face different pressures from the immune system, with those that persist ("hit-and-stay") potentially having to adapt more in order to escape than those prone to short-lived infection ("hit-and-run"), and with commensal bacteria potentially different from both due to additional physical mechanisms for avoiding immune detection. The Janus Immunogenicity Score (JIS) was recently developed to assess the likelihood of T cell recognition of an antigen, using an analysis that considers both binding of a peptide within the antigen by major histocompatability complex (MHC) and recognition of the peptide:MHC complex by cognate T cell receptor (TCR). This score was shown to be predictive of T effector vs. T regulatory or null responses in experimental data, as well as to distinguish viruses representative of the hit-and-stay vs. hit-and-run phenotypes. Here, JIS-based analyses were conducted in order to characterize the extent to which the pressure to avoid T cell recognition is manifested in genomic differences among representative hit-and-run, hit-and-stay, and commensal bacteria. Overall, extracellular proteins were found to have different JIS profiles from cytoplasmic ones. Contrasting the bacterial groups, extracellular proteins were shown to be quite different across the groups, much more so than intracellular proteins. The differences were evident even at the level of corresponding peptides in homologous protein pairs from hit-and-run and hit-and-stay bacteria. The multi-level analysis of patterns of immunogenicity across different groups of bacteria provides a new way to approach questions of bacterial immune camouflage or escape, as well as to approach the selection and optimization of candidates for vaccine design.
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Affiliation(s)
- Lu He
- Dartmouth Computer Science, Hanover, NH 03755, United States
| | - Anne S De Groot
- EpiVax, Inc., Providence, RI 02903, United States; Institute for Immunology and Informatics, University of Rhode Island, Providence, RI 02903, United States
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7
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He L, De Groot AS, Gutierrez AH, Martin WD, Moise L, Bailey-Kellogg C. Integrated assessment of predicted MHC binding and cross-conservation with self reveals patterns of viral camouflage. BMC Bioinformatics 2014; 15 Suppl 4:S1. [PMID: 25104221 PMCID: PMC4094998 DOI: 10.1186/1471-2105-15-s4-s1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Background Immune recognition of foreign proteins by T cells hinges on the formation of a ternary complex sandwiching a constituent peptide of the protein between a major histocompatibility complex (MHC) molecule and a T cell receptor (TCR). Viruses have evolved means of "camouflaging" themselves, avoiding immune recognition by reducing the MHC and/or TCR binding of their constituent peptides. Computer-driven T cell epitope mapping tools have been used to evaluate the degree to which particular viruses have used this means of avoiding immune response, but most such analyses focus on MHC-facing 'agretopes'. Here we set out a new means of evaluating the TCR faces of viral peptides in addition to their agretopes, integrating evaluations of both sides of the ternary complex in a single analysis. Methods This paper develops what we call the Janus Immunogenicity Score (JIS), bringing together a well-established method for predicting MHC binding, with a novel assessment of the potential for TCR binding based on similarity with self. Intuitively, both good MHC binding and poor self-similarity are required for high immunogenicity (i.e., a robust T effector response). Results Focusing on the class II antigen-processing pathway, we show that the JIS of T effector epitopes and null or regulatory epitopes deposited in a large database of epitopes (Immune Epitope Database) are significantly different. We then show that different types of viruses display significantly different patterns of scores over their constituent peptides, with viruses causing chronic infection (Epstein-Barr and cytomegalovirus) strongly shifted to lower scores relative to those causing acute infection (Ebola and Marburg). Similarly we find distinct patterns among influenza proteins in H1N1 (a strain against which human populations rapidly developed immunity) and H5N1 and H7N9 (highly pathogenic avian flu strains, with significantly greater case mortality rates). Conclusion The Janus Immunogenicity Score, which integrates MHC binding and TCR cross-reactivity, provides a new tool for studying immunogenicity of pathogens and may improve the selection and optimization of antigenic elements for vaccine design.
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Jawa V, Cousens LP, Awwad M, Wakshull E, Kropshofer H, De Groot AS. T-cell dependent immunogenicity of protein therapeutics: Preclinical assessment and mitigation. Clin Immunol 2013; 149:534-55. [PMID: 24263283 DOI: 10.1016/j.clim.2013.09.006] [Citation(s) in RCA: 181] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 09/13/2013] [Accepted: 09/14/2013] [Indexed: 02/07/2023]
Abstract
Protein therapeutics hold a prominent and rapidly expanding place among medicinal products. Purified blood products, recombinant cytokines, growth factors, enzyme replacement factors, monoclonal antibodies, fusion proteins, and chimeric fusion proteins are all examples of therapeutic proteins that have been developed in the past few decades and approved for use in the treatment of human disease. Despite early belief that the fully human nature of these proteins would represent a significant advantage, adverse effects associated with immune responses to some biologic therapies have become a topic of some concern. As a result, drug developers are devising strategies to assess immune responses to protein therapeutics during both the preclinical and the clinical phases of development. While there are many factors that contribute to protein immunogenicity, T cell- (thymus-) dependent (Td) responses appear to play a critical role in the development of antibody responses to biologic therapeutics. A range of methodologies to predict and measure Td immune responses to protein drugs has been developed. This review will focus on the Td contribution to immunogenicity, summarizing current approaches for the prediction and measurement of T cell-dependent immune responses to protein biologics, discussing the advantages and limitations of these technologies, and suggesting a practical approach for assessing and mitigating Td immunogenicity.
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De Groot AS, Ardito M, Terry F, Levitz L, Ross T, Moise L, Martin W. Low immunogenicity predicted for emerging avian-origin H7N9: implication for influenza vaccine design. Hum Vaccin Immunother 2013; 9:950-6. [PMID: 23807079 PMCID: PMC3899161 DOI: 10.4161/hv.24939] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A new avian-origin influenza virus emerged near Shanghai in February 2013, and by the beginning of May it had caused over 130 human infections and 36 deaths. Human-to-human transmission of avian-origin H7N9 influenza A has been limited to a few family clusters, but the high mortality rate (27%) associated with human infection has raised concern about the potential for this virus to become a significant human pathogen. European, American, and Asian vaccine companies have already initiated the process of cloning H7 antigens such as hemagglutinin (HA) into standardized vaccine production vehicles. Unfortunately, previous H7 HA-containing vaccines have been poorly immunogenic. We used well-established immunoinformatics tools to analyze the H7N9 protein sequences and compare their T cell epitope content to other circulating influenza A strains as a means of estimating the immunogenic potential of the new influenza antigen. We found that the HA proteins derived from closely related human-derived H7N9 strains contain fewer T cell epitopes than other recently circulating strains of influenza, and that conservation of T cell epitopes with other strains of influenza was very limited. Here, we provide a detailed accounting of the type and location of T cell epitopes contained in H7N9 and their conservation in other H7 and circulating (A/California/07/2009, A/Victoria/361/2011, and A/Texas/50/2012) influenza A strains. Based on this analysis, avian-origin H7N9 2013 appears to be a “stealth” virus, capable of evading human cellular and humoral immune response. Should H7N9 develop pandemic potential, this analysis predicts that novel strategies for improving vaccine immunogenicity for this unique low-immunogenicity strain of avian-origin influenza will be urgently needed.
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Affiliation(s)
- Anne S De Groot
- Institute for Immunology and Informatics; University of Rhode Island; Providence, RI USA; EpiVax, Inc.; Providence, RI USA
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Gutiérrez AH, Moise L, De Groot AS. Of [Hamsters] and men: a new perspective on host cell proteins. Hum Vaccin Immunother 2012; 8:1172-4. [PMID: 23124469 PMCID: PMC3579895 DOI: 10.4161/hv.22378] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Andres H. Gutiérrez
- Institute for Immunology and Informatics, University of Rhode Island; Providence, RI USA
| | - Leonard Moise
- Institute for Immunology and Informatics, University of Rhode Island; Providence, RI USA
- EpiVax Inc.; Providence, RI USA
| | - Annie S. De Groot
- Institute for Immunology and Informatics, University of Rhode Island; Providence, RI USA
- EpiVax Inc.; Providence, RI USA
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Abstract
Antibodies make up the largest, growing segment of protein therapeutics in the pharmaceutical and biotechnology industries. The development or engineering of therapeutic antibodies is based to a large extent on our knowledge of antibody structure and requires sophisticated methods that continue to evolve. In this chapter, after a review of what is known about the structure and functional properties of antibodies, the current, state-of-the-art antibody engineering methods are described. These methods include antibody humanization, antigen-affinity optimization, Fc engineering for modulated effector function and extended half-life, and engineering for improved stability and biophysical properties. X-ray crystallographic structures of antibody fragments and their complexes can play a critical role in guiding and, in some cases, accelerating these processes. These approaches represent guidelines for developing antibody therapeutics with the desired affinity, effector function, and biophysical properties.
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De Groot AS. Exploring the immunome: A brave new world for human vaccine development. HUMAN VACCINES 2009; 5:790-3. [PMID: 20009527 DOI: 10.4161/hv.10683] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Anne S De Groot
- Institute for Immunology and Informatics, University of Rhode Island, Providence, RI, USA.
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13
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Jones TD, Crompton LJ, Carr FJ, Baker MP. Deimmunization of monoclonal antibodies. Methods Mol Biol 2009; 525:405-23, xiv. [PMID: 19252848 DOI: 10.1007/978-1-59745-554-1_21] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Immunogenicity is a major limitation to therapy with certain monoclonal antibodies and proteins. A major driver for immunogenicity is the presence of human T-cell epitopes within the protein sequence which can activate helper T-cells resulting in the sustained production of antibodies and neutralization of the therapeutic effect. Deimmunization is a new technology for location and removal of T-cell epitopes through the combined use of immunological and molecular biology techniques. In the case of deimmunization of antibodies, mutations to remove T-cell epitopes can generally be introduced without significantly reducing the binding affinity of the antibody. Typically, "deimmunized" antibodies are created with human constant regions and by expression of genes encoding these antibodies in mammalian cells. This chapter details a method for creation of a deimmunized antibody for production in mammalian cells.
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Knopf PM, Rivera DS, Hai SH, McMurry J, Martin W, De Groot AS. Novel function of complement C3d as an autologous helper T-cell target. Immunol Cell Biol 2008; 86:221-5. [PMID: 18180801 DOI: 10.1038/sj.icb.7100147] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The C3d fragment of complement component C3 has been shown to enhance immune responses to antigens that lack T-cell epitopes such as bacterial polysaccharides. C3d binds to the B-cell complement receptor 2 (CR2 or CD21); this binding serves as a co-activation signal to the B cell when the polysaccharide antigen portion binds simultaneously to the B-cell receptor (surface Ig). Bringing together receptor-associated signal transduction molecules CD19 and Igalpha/beta, respectively, results in a lower threshold of activation. Paradoxically, C3d has also been shown to enhance antibody titers in the CD21 knockout (KO) mouse model as well as increase Th1 and Th2 cytokine secretion, suggesting that that an auxiliary CR2-independent pathway of immune activation may exist. We hypothesized that in addition to its molecular adjuvant property that enhances signal 1 during B-cell activation (co-signal 1), C3d also contains T-cell epitopes that are able to stimulate autoreactive C3d peptide-specific helper T cells which we term 'co-signal 2'. Using the EpiMatrix T-cell epitope-mapping algorithm, we identified 11 putative T-cell epitopes in C3d, a very high epitope density for a 302 amino-acid sequence. Eight of these epitope candidates were synthesized and shown to bind a variety of class II HLA-DR molecules of different haplotypes, and to stimulate C3d peptide-specific T cells to secrete pro-inflammatory cytokines in vitro. Further, we demonstrate a C3d-peptide specific increase in CD4(+) intracellular IFN-gamma(+) T cells in peripheral blood mononuclear cells (PBMCs) exposed to C3d peptides in vitro. We believe that the discovery of these autologous T cells autoreactive for C3d provides evidence supporting the 'co-signal 2' hypothesis and may offer a novel explanation of the CD21 KO paradox.
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Affiliation(s)
- Paul M Knopf
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA.
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