1
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Davies AM, Beavil RL, Barbolov M, Sandhar BS, Gould HJ, Beavil AJ, Sutton BJ, McDonnell JM. Crystal structures of the human IgD Fab reveal insights into C H1 domain diversity. Mol Immunol 2023; 159:28-37. [PMID: 37267832 DOI: 10.1016/j.molimm.2023.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 05/17/2023] [Accepted: 05/20/2023] [Indexed: 06/04/2023]
Abstract
Antibodies of the IgD isotype remain the least well characterized of the mammalian immunoglobulin isotypes. Here we report three-dimensional structures for the Fab region of IgD, based on four different crystal structures, at resolutions of 1.45-2.75 Å. These IgD Fab crystals provide the first high-resolution views of the unique Cδ1 domain. Structural comparisons identify regions of conformational diversity within the Cδ1 domain, as well as among the homologous domains of Cα1, Cγ1 and Cμ1. The IgD Fab structure also possesses a unique conformation of the upper hinge region, which may contribute to the overall disposition of the very long linker sequence between the Fab and Fc regions found in human IgD. Structural similarities observed between IgD and IgG, and differences with IgA and IgM, are consistent with predicted evolutionary relationships for the mammalian antibody isotypes.
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Affiliation(s)
- Anna M Davies
- King's College London, Randall Centre for Cell and Molecular Biophysics, New Hunt's House, London SE1 1UL, United Kingdom
| | - Rebecca L Beavil
- King's College London, Randall Centre for Cell and Molecular Biophysics, New Hunt's House, London SE1 1UL, United Kingdom
| | - Momchil Barbolov
- King's College London, Randall Centre for Cell and Molecular Biophysics, New Hunt's House, London SE1 1UL, United Kingdom
| | - Balraj S Sandhar
- King's College London, Randall Centre for Cell and Molecular Biophysics, New Hunt's House, London SE1 1UL, United Kingdom
| | - Hannah J Gould
- King's College London, Randall Centre for Cell and Molecular Biophysics, New Hunt's House, London SE1 1UL, United Kingdom
| | - Andrew J Beavil
- King's College London, Randall Centre for Cell and Molecular Biophysics, New Hunt's House, London SE1 1UL, United Kingdom
| | - Brian J Sutton
- King's College London, Randall Centre for Cell and Molecular Biophysics, New Hunt's House, London SE1 1UL, United Kingdom
| | - James M McDonnell
- King's College London, Randall Centre for Cell and Molecular Biophysics, New Hunt's House, London SE1 1UL, United Kingdom.
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2
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Ohm-Laursen L, Meng H, Hoehn KB, Nouri N, Jiang Y, Clouser C, Johnstone TG, Hause R, Sandhar BS, Upton NEG, Chevretton EB, Lakhani R, Corrigan CJ, Kleinstein SH, Gould HJ. B Cell Mobilization, Dissemination, Fine Tuning of Local Antigen Specificity and Isotype Selection in Asthma. Front Immunol 2021; 12:702074. [PMID: 34721376 PMCID: PMC8552043 DOI: 10.3389/fimmu.2021.702074] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 09/06/2021] [Indexed: 12/30/2022] Open
Abstract
In order to better understand how the immune system interacts with environmental triggers to produce organ-specific disease, we here address the hypothesis that B and plasma cells are free to migrate through the mucosal surfaces of the upper and lower respiratory tracts, and that their total antibody repertoire is modified in a common respiratory tract disease, in this case atopic asthma. Using Adaptive Immune Receptor Repertoire sequencing (AIRR-seq) we have catalogued the antibody repertoires of B cell clones retrieved near contemporaneously from multiple sites in the upper and lower respiratory tract mucosa of adult volunteers with atopic asthma and non-atopic controls and traced their migration. We show that the lower and upper respiratory tracts are immunologically connected, with trafficking of B cells directionally biased from the upper to the lower respiratory tract and points of selection when migrating from the nasal mucosa and into the bronchial mucosa. The repertoires are characterized by both IgD-only B cells and others undergoing class switch recombination, with restriction of the antibody repertoire distinct in asthmatics compared with controls. We conclude that B cells and plasma cells migrate freely throughout the respiratory tract and exhibit distinct antibody repertoires in health and disease.
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Affiliation(s)
- Line Ohm-Laursen
- Randall Centre for Cell and Molecular Biophysics and School of Basic and Medical Biosciences, King’s College London, London, United Kingdom
- Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom
| | - Hailong Meng
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States
| | - Kenneth B. Hoehn
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States
| | - Nima Nouri
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States
- Center for Medical Informatics, Yale School of Medicine, New Haven, CT, United States
| | - Yue Jiang
- Bristol Myers Squibb, Seattle, WA, United States
| | | | | | - Ron Hause
- Bristol Myers Squibb, Seattle, WA, United States
| | - Balraj S. Sandhar
- Randall Centre for Cell and Molecular Biophysics and School of Basic and Medical Biosciences, King’s College London, London, United Kingdom
- Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom
| | - Nadine E. G. Upton
- Randall Centre for Cell and Molecular Biophysics and School of Basic and Medical Biosciences, King’s College London, London, United Kingdom
- Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom
| | - Elfy B. Chevretton
- Department of Ear, Nose and Throat (ENT) Services, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom
| | - Raj Lakhani
- Department of Ear, Nose and Throat (ENT) Services, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom
| | - Chris J. Corrigan
- Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom
- Department of Respiratory Medicine and Allergy and School of Immunology and Microbial Sciences, King’s College London, London, United Kingdom
| | - Steven H. Kleinstein
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States
- Interdepartmental Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT, United States
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, United States
| | - Hannah J. Gould
- Randall Centre for Cell and Molecular Biophysics and School of Basic and Medical Biosciences, King’s College London, London, United Kingdom
- Asthma UK Centre in Allergic Mechanisms of Asthma, London, United Kingdom
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3
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Lymphocyte predominant cells detect Moraxella catarrhalis-derived antigens in nodular lymphocyte-predominant Hodgkin lymphoma. Nat Commun 2020; 11:2465. [PMID: 32424289 PMCID: PMC7235000 DOI: 10.1038/s41467-020-16375-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 04/28/2020] [Indexed: 02/06/2023] Open
Abstract
Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare lymphoma of B-cell origin with frequent expression of functional B-cell receptors (BCRs). Here we report that expression cloning followed by antigen screening identifies DNA-directed RNA polymerase beta’ (RpoC) from Moraxella catarrhalis as frequent antigen of BCRs of IgD+ LP cells. Patients show predominance of HLA-DRB1*04/07 and the IgVH genes encode extraordinarily long CDR3s. High-titer, light-chain-restricted anti-RpoC IgG1/κ-type serum-antibodies are additionally found in these patients. RpoC and MID/hag, a superantigen co-expressed by Moraxella catarrhalis that is known to activate IgD+ B cells by binding to the Fc domain of IgD, have additive activation effects on the BCR, the NF-κB pathway and the proliferation of IgD+ DEV cells expressing RpoC-specific BCRs. This suggests an additive antigenic and superantigenic stimulation of B cells with RpoC-specific IgD+ BCRs under conditions of a permissive MHC-II haplotype as a model of NLPHL lymphomagenesis, implying future treatment strategies. Nodular lymphocyte-predominant Hodgkin lymphoma with IgD+ lymphocyte-predominant (LP) cells is a rare clinical distinct lymphoma subset of B-cell origin. Here the authors show that antigens expressed by Moraxella catarrhalis are recognized by B cell receptors of IgD+ LP cells, suggesting the contribution of chronic antigen stimulation to lymphomagenesis.
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4
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Gutzeit C, Chen K, Cerutti A. The enigmatic function of IgD: some answers at last. Eur J Immunol 2018; 48:1101-1113. [PMID: 29733429 DOI: 10.1002/eji.201646547] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/27/2018] [Accepted: 04/17/2018] [Indexed: 12/20/2022]
Abstract
IgD emerged soon after IgM at the time of inception of the adaptive immune system. Despite its evolutionary conservation from fish to humans, the specific functions of IgD have only recently begun to be elucidated. Mature B cells undergo alternative mRNA splicing to express IgD and IgM receptors with identical antigenic specificity. The enigma of dual IgD and IgM expression has been tackled by several recent studies showing that IgD helps peripheral accumulation of physiologically autoreactive B cells through its functional unresponsiveness to self-antigens but prompt readiness against foreign antigens. IgD achieves this balance by attenuating IgM-mediated anergy while promoting specific responses to multimeric non-self-antigens. Additional research has clarified how and why certain mucosal B cells become plasmablasts or plasma cells specializing in IgD secretion. In particular, the microbiota has been shown to play an important role in driving class switch-mediated replacement of IgM with IgD. Secreted IgD appears to enhance mucosal homeostasis and immune surveillance by "arming" myeloid effector cells such as basophils and mast cells with IgD antibodies reactive against mucosal antigens, including commensal and pathogenic microbes. Here we will review these advances and discuss their implications in humoral immunity in human and mice.
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Affiliation(s)
- Cindy Gutzeit
- Immunology Institute, Department of Medicine, Mount Sinai Icahn School of Medicine, New York, NY, USA
| | - Kang Chen
- Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA.,Mucosal Immunology Studies Team (MIST), National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Andrea Cerutti
- Immunology Institute, Department of Medicine, Mount Sinai Icahn School of Medicine, New York, NY, USA.,Mucosal Immunology Studies Team (MIST), National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.,Program for Inflammatory and Cardiovascular Disorders, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain.,Catalan Institute for Research and Advanced Studies (ICREA), Barcelona, Spain
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5
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Affiliation(s)
- Nika Kruljec
- Faculty
of Pharmacy, University of Ljubljana, Aškerčeva 7, SI-1000 Ljubljana, Slovenia
| | - Tomaž Bratkovič
- Faculty
of Pharmacy, University of Ljubljana, Aškerčeva 7, SI-1000 Ljubljana, Slovenia
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6
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Singh K, Nordström T, Mörgelin M, Brant M, Cardell LO, Riesbeck K. Haemophilus influenzae resides in tonsils and uses immunoglobulin D binding as an evasion strategy. J Infect Dis 2013; 209:1418-28. [PMID: 24218509 DOI: 10.1093/infdis/jit593] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Haemophilus influenzae (Hi) causes respiratory tract infections and is also considered to be a commensal, particularly in preschool children. Tonsils from patients (n = 617) undergoing tonsillectomy due to chronic infection or hypertrophy were examined. We found that 51% of tonsils were positive for Hi, and in 95% of cases analyzed in detail (n = 39) Hi resided intracellularly in the core tonsillar tissue. Patients harbored several intracellular unique strains and the majority were nontypeable Hi (NTHi). Interestingly, the isolated NTHi bound soluble immunoglobulin (Ig) D at the constant heavy chain domain 1 as revealed by recombinant IgD/IgG chimeras. NTHi also interacted with B lymphocytes via the IgD B-cell receptor, resulting in internalization of bacteria, T-cell-independent activation via Toll-like receptor 9, and differentiation into non-NTHi-specific IgM-producing cells. Taken together, IgD-binding NTHi leads to an unspecific immune response and may support the bacteria to circumvent the host defense.
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Affiliation(s)
- Kalpana Singh
- Medical Microbiology, Department of Laboratory Medicine Malmö, Lund University, Malmö
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7
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Edholm ES, Bengtén E, Stafford JL, Sahoo M, Taylor EB, Miller NW, Wilson M. Identification of two IgD+ B cell populations in channel catfish, Ictalurus punctatus. THE JOURNAL OF IMMUNOLOGY 2010; 185:4082-94. [PMID: 20817869 DOI: 10.4049/jimmunol.1000631] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Channel catfish Ictalurus punctatus express two Ig isotypes: IgM and IgD. Although catfish IgM has been extensively studied at the functional and structural levels, much less is known about IgD. In this study, IgM(+)/IgD(+) and IgM(-)/IgD(+) catfish B cell populations were identified through the use of anti-IgM and anti-IgD mAbs. Catfish IgM(+)/IgD(+) B cells are small and agranular. In contrast, IgM(-)/IgD(+) B cells are larger and exhibit a plasmablast morphology. The use of cell sorting, flow cytometry, and RT-PCR demonstrated that IgD(+) B cell expression varies among individuals. For example, some catfish have <5% IgM(-)/IgD(+) B cells in their PBLs, whereas in others the IgM(-)/IgD(+) B cell population can represent as much as 72%. Furthermore, IgD expressed by IgM(-)/IgD(+) B cells preferentially associates with IgL σ. Comparatively, IgM(+)/IgD(+) B cells can express any of the four catfish IgL isotypes. Also, transfection studies show that IgD functions as a typical BCR, because Igδ-chains associate with CD79a and CD79b molecules, and all membrane IgD transcripts from sorted IgM(-)/IgD(+) B cells contain viable VDJ rearrangements, with no bias in family member usage. Interestingly, all secreted IgD transcripts from IgM(+)/IgD(+) and IgM(-)/IgD(+) B cells were V-less and began with a leader spliced to Cδ1. Importantly, transfection of catfish clonal B cells demonstrated that this leader mediated IgD secretion. Together, these findings imply that catfish IgM(-)/IgD(+) B cells likely expand in response to certain pathogens and that the catfish IgD Fc-region, as has been suggested for human IgD, may function as a pattern recognition molecule.
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Affiliation(s)
- Eva-Stina Edholm
- Department of Microbiology, University of Mississippi Medical Center, Jackson, MS 39216, USA
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8
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Perez Vidakovics MLA, Jendholm J, Mörgelin M, Månsson A, Larsson C, Cardell LO, Riesbeck K. B cell activation by outer membrane vesicles--a novel virulence mechanism. PLoS Pathog 2010; 6:e1000724. [PMID: 20090836 PMCID: PMC2799554 DOI: 10.1371/journal.ppat.1000724] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 12/10/2009] [Indexed: 12/13/2022] Open
Abstract
Secretion of outer membrane vesicles (OMV) is an intriguing phenomenon of Gram-negative bacteria and has been suggested to play a role as virulence factors. The respiratory pathogens Moraxella catarrhalis reside in tonsils adjacent to B cells, and we have previously shown that M. catarrhalis induce a T cell independent B cell response by the immunoglobulin (Ig) D-binding superantigen MID. Here we demonstrate that Moraxella are endocytosed and killed by human tonsillar B cells, whereas OMV have the potential to interact and activate B cells leading to bacterial rescue. The B cell response induced by OMV begins with IgD B cell receptor (BCR) clustering and Ca(2+) mobilization followed by BCR internalization. In addition to IgD BCR, TLR9 and TLR2 were found to colocalize in lipid raft motifs after exposure to OMV. Two components of the OMV, i.e., MID and unmethylated CpG-DNA motifs, were found to be critical for B cell activation. OMV containing MID bound to and activated tonsillar CD19(+) IgD(+) lymphocytes resulting in IL-6 and IgM production in addition to increased surface marker density (HLA-DR, CD45, CD64, and CD86), whereas MID-deficient OMV failed to induce B cell activation. DNA associated with OMV induced full B cell activation by signaling through TLR9. Importantly, this concept was verified in vivo, as OMV equipped with MID and DNA were found in a 9-year old patient suffering from Moraxella sinusitis. In conclusion, Moraxella avoid direct interaction with host B cells by redirecting the adaptive humoral immune response using its superantigen-bearing OMV as decoys.
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MESH Headings
- Adhesins, Bacterial/immunology
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- Blotting, Western
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Cell Separation
- Child
- Child, Preschool
- CpG Islands/immunology
- Electrophoresis, Polyacrylamide Gel
- Enzyme-Linked Immunosorbent Assay
- Flow Cytometry
- Humans
- Immunoglobulin D/immunology
- Lymphocyte Activation/immunology
- Membrane Microdomains/immunology
- Membrane Microdomains/metabolism
- Microscopy, Confocal
- Microscopy, Electron, Transmission
- Microscopy, Fluorescence
- Moraxella catarrhalis/immunology
- Moraxella catarrhalis/pathogenicity
- Moraxellaceae Infections/immunology
- Palatine Tonsil/immunology
- Receptors, Antigen, B-Cell/immunology
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/immunology
- Sinusitis/immunology
- Sinusitis/microbiology
- Virulence
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Affiliation(s)
| | - Johan Jendholm
- Medical Microbiology, Department of Laboratory Medicine, University Hospital Malmö, Lund University, Malmö, Sweden
| | - Matthias Mörgelin
- Section of Clinical and Experimental Infectious Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Anne Månsson
- Division of ENT Diseases, Department of Clinical Sciences, Intervention and Technology, Karolinska Institute, Huddinge, Sweden
| | - Christer Larsson
- Center for Molecular Pathology, Department of Laboratory Medicine, University Hospital Malmö, Lund University, Malmö, Sweden
| | - Lars-Olaf Cardell
- Division of ENT Diseases, Department of Clinical Sciences, Intervention and Technology, Karolinska Institute, Huddinge, Sweden
| | - Kristian Riesbeck
- Medical Microbiology, Department of Laboratory Medicine, University Hospital Malmö, Lund University, Malmö, Sweden
- * E-mail:
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9
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Jendholm J, Mörgelin M, Perez Vidakovics MLA, Carlsson M, Leffler H, Cardell LO, Riesbeck K. Superantigen- and TLR-dependent activation of tonsillar B cells after receptor-mediated endocytosis. THE JOURNAL OF IMMUNOLOGY 2009; 182:4713-20. [PMID: 19342647 DOI: 10.4049/jimmunol.0803032] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Classical B lymphocyte activation is dependent on BCR cross-linking in combination with physical interaction with Th cells. Other B cell molecules that contribute to the activation are complement, cytokine, and TLRs recognizing specific pathogen-associated molecular patterns. Moraxella (Branhamella) catarrhalis is a common Gram-negative respiratory pathogen that induces proliferation in human IgD-expressing B cells independently of T cell help. The activation is initiated by the B cell superantigen Moraxella IgD-binding protein (MID) through a nonimmune cross-linking of IgD. However, IgD cross-linking alone is not sufficient to induce proliferation. In this study, we characterized the significance of TLRs in superantigen-dependent B cell activation using whole bacteria or rMID in the presence or absence of TLR ligands. IgD cross-linking by MID sensitized B cells obtained from children with tonsillar hyperplasia for mainly TLR9, whereas TLRs 1, 2, 6, and 7 were less important. The Moraxella-induced activation was inhibited when a dominant-negative TLR9 ligand was added. Interestingly, BCR-mediated endocytosis of whole Moraxella and degradation of live bacteria in naive B cells were observed with fluorescence, confocal, and transmission electron microscopy. This unique observation proved the strong intracellular TLR9 response as well as highlighted the Ag-presenting function of B cells. In conclusion, our findings suggest an important role of TLRs in the adaptive immune response and reveal novel insights into the T cell-independent B cell activation induced by bacteria.
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Affiliation(s)
- Johan Jendholm
- Department of Laboratory Medicine, University Hospital Malmö, Lund University, Malmö, Sweden
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10
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Samuelsson M, Hallström T, Forsgren A, Riesbeck K. Characterization of the IgD binding site of encapsulated Haemophilus influenzae serotype b. THE JOURNAL OF IMMUNOLOGY 2007; 178:6316-9. [PMID: 17475860 DOI: 10.4049/jimmunol.178.10.6316] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Encapsulated Haemophilus influenzae is a causative agent of invasive disease, such as meningitis and septicemia. Several interactions exist between H. influenzae and the human host. H. influenzae has been reported to bind IgD in a nonimmune manner, but the responsible protein has not yet been identified. To define the binding site on IgD for H. influenzae, full-length IgD and four chimeric IgDs with interspersed IgG sequences and Ag specificity for dansyl chloride were expressed in stably transfected Chinese hamster ovary cells. The binding of recombinant IgD to a panel of encapsulated H. influenzae serotype b (Hib) and nontypeable strains were investigated using a whole cell ELISA and flow cytometry. IgD binding was detected in 50% of the encapsulated Hib strains examined, whereas nontypeable H. influenzae did not interact with IgD. Finally, mapping experiments using the chimeric IgD/IgG indicated that IgD CH1 aa 198-224 were involved in the interaction between IgD and H. influenzae. Thus, by using recombinant IgD and chimeras with defined Ag specificity, we have confirmed that Hib specifically binds IgD, and that this binding involves the IgD CH1 region.
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Affiliation(s)
- Martin Samuelsson
- Medical Microbiology, Department of Laboratory Medicine, Lund University, Malmö University Hospital, Malmö, Sweden
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11
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Samuelsson M, Forsgren A, Riesbeck K. Purification of IgD from human serum--a novel application of recombinant M. catarrhalis IgD-binding protein (MID). J Immunol Methods 2006; 317:31-7. [PMID: 17056056 DOI: 10.1016/j.jim.2006.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 08/23/2006] [Accepted: 09/07/2006] [Indexed: 11/20/2022]
Abstract
Moraxella catarrhalis IgD-binding protein (MID) is a multimeric outer membrane protein belonging to the family of autotransporters. The IgD-binding domain of MID is located between amino acids MID 962-1200 and binds to amino acids 198-224 of the IgD C(H)1 region. In the present study, we describe a method to purify IgD from serum with high levels of IgD using a two-step affinity chromatography process. The first step involves depletion of MID-specific antibodies of all classes from serum using the non-IgD-binding fragment MID(1000-1200). This step is followed by selective capture of IgD with MID(962-1200). Furthermore, we demonstrate that the eluted IgD is pure, intact and functional for use in downstream applications. Our approach reduces the non-specificity commonly associated with lectin-based IgD purification regimes that rely on glycosylation of the IgD molecule.
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Affiliation(s)
- Martin Samuelsson
- Medical Microbiology, Department of Laboratory Medicine, Lund University, Malmö University Hospital, SE-205 02 Malmö, Sweden
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