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Abstract
The multiple inter-dependent post-translational modifications of histones represent fine regulators of chromatin dynamics. These covalent modifications, including phosphorylation, acetylation, ubiquitination, deimination, and methylation, affect therefore the numerous processes involving chromatin, such as replication, repair, transcription, genome stability, and cell death. Specific enzymes introducing modified residues in histones are precisely regulated, and a single amino acid residue can be subjected to a single or several, independent modifications. Disruption of histone post-translational modifications perturbs the pattern of gene expression, which may result in disease manifestations. It has become evident in recent years that apoptosis-modified histones exert a central role in the induction of autoimmunity, for example in systemic lupus erythematosus and rheumatoid arthritis. Certain histone post-translational modifications are linked to cell death (apoptotic and non-apoptotic cell death) and might be involved in lupus in the activation of normally tolerant lymphocyte subpopulations. In this review, we discuss how these modifications can affect the antigenicity and immunogenicity of histones with potential consequences in the pathogenesis of autoimmune diseases.
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2
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Mason LJ, Ravirajan CT, Rahman A, Putterman C, Isenberg DA. Is alpha-actinin a target for pathogenic anti-DNA antibodies in lupus nephritis? ACTA ACUST UNITED AC 2004; 50:866-70. [PMID: 15022329 DOI: 10.1002/art.20103] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Following recent reports that pathogenic murine anti-DNA antibodies bind to alpha-actinin, it was obviously of interest to assess the ability of human pathogenic anti-double-stranded DNA (anti-dsDNA) antibodies to bind this antigen. Both human monoclonal anti-DNA antibodies and antibodies affinity purified from the sera of patients with systemic lupus erythematosus (SLE) were investigated. METHODS An enzyme-linked immunosorbent assay was established to measure immunoglobulin binding to alpha-actinin. Antibodies binding dsDNA were purified from the sera of SLE patients who either had active renal disease or had never had renal disease. Serum samples were selected at times when the patients' sera exhibited high IgG binding to dsDNA. The binding of supernatants from 3 high-affinity human anti-dsDNA IgG hybridomas (RH14, B3, and DIL-6) and 7 human IgM anti-DNA hybridomas was also investigated. RESULTS A greater proportion of anti-dsDNA IgG-binding antibodies purified from patients with renal disease bound to alpha-actinin than did those purified from the sera of patients without renal disease. The specificity of binding to the 100-kd alpha-actinin molecule was confirmed by Western blotting. The pathogenic human antibodies RH14 and B3 bound strongly to alpha-actinin, while nonpathogenic DIL-6 bound very weakly. RT84, the IgM antibody that binds dsDNA with the highest affinity, exhibited the greatest binding to alpha-actinin. CONCLUSION The results of our study support the findings of previous studies using murine anti-DNA monoclonal antibodies, which suggest that pathogenic anti-dsDNA antibodies cross-react with alpha-actinin.
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Affiliation(s)
- Lesley J Mason
- Department of Medicine, University College London, London, UK.
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3
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Fraser NLW, Rowley G, Field M, Stott DI. The VH gene repertoire of splenic B cells and somatic hypermutation in systemic lupus erythematosus. Arthritis Res Ther 2003; 5:R114-21. [PMID: 12718755 PMCID: PMC165037 DOI: 10.1186/ar627] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2002] [Revised: 12/18/2002] [Accepted: 01/05/2003] [Indexed: 11/10/2022] Open
Abstract
In systemic lupus erythematosus (SLE) it has been hypothesized that self-reactive B cells arise from virgin B cells that express low-affinity, nonpathogenic germline V genes that are cross-reactive for self and microbial antigens, which convert to high-affinity autoantibodies via somatic hypermutation. The aim of the present study was to determine whether the VH family repertoire and pattern of somatic hypermutation in germinal centre (GC) B cells deviates from normal in SLE. Rearranged immunoglobulin VH genes were cloned and sequenced from GCs of a SLE patient's spleen. From these data the GC V gene repertoire and the pattern of somatic mutation during the proliferation of B-cell clones were determined. The results highlighted a bias in VH5 gene family usage, previously unreported in SLE, and under-representation of the VH1 family, which is expressed in 20-30% of IgM+ B cells of healthy adults and confirmed a defect in negative selection. This is the first study of the splenic GC response in human SLE.
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Affiliation(s)
- Nicola L W Fraser
- Division of Immunology, Infection and Inflammation, University of Glasgow, Western Infirmary, Glasgow, Scotland, UK.
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4
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Sharma A, Isenberg DA, Diamond B. Crossreactivity of human anti-dsDNA antibodies to phosphorylcholine: clues to their origin. J Autoimmun 2001; 16:479-84. [PMID: 11437497 DOI: 10.1006/jaut.2001.0514] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The presence of anti-double stranded DNA (dsDNA) antibodies is a serological diagnostic feature of systemic lupus erythematosus (SLE), an autoimmune rheumatic disorder. Studies by several investigators have suggested that a response to a microbial antigen can lead to the induction of SLE-like autoimmunity, in both humans and mice, since anti-dsDNA antibodies have been shown to crossreact with foreign antigens. In particular, anti-DNA antibodies have been shown to crossreact with phosphorylcholine (PC), a dominant epitope on pneumococcal cell wall polysaccharide. We have investigated the binding characteristics of human polyclonal anti-DNA antibodies from the sera of SLE patients. In this study we show that the DNA binding of polyclonal serum derived antibodies can be partially inhibited by phosphorylcholine (PC). The binding of affinity-purified anti-DNA antibodies from the sera of patients with SLE was also found to be inhibited by PC. We further demonstrated that the serum IgG1 (T dependent) anti-DNA response was more likely to crossreact with PC than the IgG2 (T independent) response to DNA. The studies suggest there may be a T dependent and T independent response to DNA with the T dependent response displaying more crossreactivity with microbial antigen.
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Affiliation(s)
- A Sharma
- Bloomsbury Rheumatology Unit/Centre for Rheumatology, Dept of Medicine, University College London, Arthur Stanley House, London, W1P 9PG, UK
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Kumar S, Kalsi J, Ravirajan CT, Rahman A, Athwal D, Latchman DS, Isenberg DA, Pearl LH. Molecular cloning and expression of the Fabs of human autoantibodies in Escherichia coli. Determination of the heavy or light chain contribution to the anti-DNA/-cardiolipin activity of the Fab. J Biol Chem 2000; 275:35129-36. [PMID: 10893224 DOI: 10.1074/jbc.m001976200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Fabs of three human autoantibodies (B3/33H11, anti-DNA; UK4, anti-phospholipid) and six related hybrids have been cloned, expressed in Escherichia coli, and purified to homogeneity. SDS-polyacrylamide gel electrophoresis and Western blot analysis of the recombinant Fab demonstrated the purified Fab to be of correct size and in assembled form. Protein expression levels of up to 5-9 mg per liter of culture were achievable. A sensitive and reliable comparative anti-DNA enzyme-linked immunosorbent assay, involving a defined biotinylated 35-mer oligonucleotide in its single- or double-stranded form, is also described. Crithidia assay and anti-DNA or anti-cardiolipin antibody enzyme-linked immunosorbent assay analyses demonstrated convincing binding of the recombinant Fab proteins to DNA/cardiolipin, confirming the expression of functional molecule. The comparative DNA/cardiolipin binding analyses of the nine Fabs revealed that the anti-DNA (light, B3/33H11) or anti-cardiolipin (heavy, UK4) activity lies predominantly on one of the two chains. However, a compatible partner chain is necessary for optimum antigen binding activity of the antibody.
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Affiliation(s)
- S Kumar
- Centre for Rheumatology, Bloomsbury Rheumatology Unit, the Department of Medicine and the Department of Biochemistry and Molecular Biology, University College London, London W1P 9PG, UK.
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6
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Pittoni V, Ravirajan CT, Donohoe S, MacHin SJ, Lydyard PM, Isenberg DA. Human monoclonal anti-phospholipid antibodies selectively bind to membrane phospholipid and beta2-glycoprotein I (beta2-GPI) on apoptotic cells. Clin Exp Immunol 2000; 119:533-43. [PMID: 10691928 PMCID: PMC1905581 DOI: 10.1046/j.1365-2249.2000.01161.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability of an anti-phospholipid (LJ1) and an anti-beta2-GPI (RSP-57) human MoAb to bind to apoptotic but not viable cells was demonstrated in this study. Both MoAbs were derived from patients with systemic lupus erythematosus and anti-phospholipid antibody syndrome. The parallel analysis of the specificity and affinity of four anti-phospholipid human MoAbs suggests that the binding of LJ1 MoAb to apoptotic cells is a specific property of this MoAb. RSP-57 MoAb recognizes apoptotic cells through beta2-GPI which becomes available for binding after the interaction with negatively charged phospholipids. This observation provides evidence that the binding of human anti-phospholipid antibodies to apoptotic cells occurs in both a beta2-GPI-dependent and independent way and involves a restricted group of epitopes. The finding that LJ1 and RSP-57 MoAbs bind apoptotic cells underlines the property of these MoAbs to act as cell membrane markers of apoptosis. Major pathological implications derive from the observation that LJ1 and RSP-57 MoAbs recognize epitopes expressed on 'early' apoptotic cells. The interference with the in vivo clearance and processing of apoptotic cells is a potential pathogenic mechanism of these antibodies.
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Affiliation(s)
- V Pittoni
- Centre for Rheumatology/Bloomsbury Rheumatology Unit, Department of Medicine and Department of Haematology, University College London, London, UK
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7
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von Landenberg C, Lackner KJ, von Landenberg P, Lang B, Schmitz G. Isolation and characterization of two human monoclonal anti-phospholipid IgG from patients with autoimmune disease. J Autoimmun 1999; 13:215-23. [PMID: 10479390 DOI: 10.1006/jaut.1999.0316] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The antigenic specificity of anti-phospholipid antibodies (APA) is a matter of intensive investigation. To further characterize these antibodies, we attempted to isolate human monoclonal APA. B-cells of patients with at least one positive test for antibodies against cardiolipin, phosphatidylserine, beta2-glycoprotein I (beta2-GPI) or the lupus anti-coagulant were immortalized by transformation with Epstein-Barr virus and screened for production of specific IgG. Positive pools were fused with a heteromyeloma cell line and APA-secreting clones were isolated by standard procedures. Two monoclonal APA, HL-5B from a 51-year-old man with primary anti-phospholipid syndrome and recurrent cerebral microinfarctions, and RR-7F from a 48-year-old women with systemic lupus erythematosus but no evidence for thrombotic events were obtained. HL-5B is of the IgG2 subtype with lambda light chains, while RR-7F is IgG2 with kappa light chains. Both monoclonals show reactivity against cardiolipin and phosphatidylserine but lack reactivity against beta2-GPI or lupus anti-coagulant activity. To yield the same OD in the cardiolipin and phosphatidylserine ELISAs RR-7F must be used in an approximately 10-fold higher concentration than HL-5B, indicating a lower affinity towards these antigens. Interestingly, both mAPA can bind to cardiolipin in the absence of beta2-GPI. They do not cross-react with dsDNA but show reactivity against oxidized low-density lipoproteins. Analysis of the heavy chain mRNA of HL-5B and RR-7F showed that both are members of the VH3 family. While HL-5B shows extensive somatic mutations in the CDR1 and 2 regions, indicating that it was derived by a T cell-dependent antigen driven process, RR-7F is apparently germline encoded. The two monoclonal APA can be used as tools in further structural and functional analyses.
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Affiliation(s)
- C von Landenberg
- Institute for Clinical Chemistry and Laboratory Medicine, University Hospital of Regensburg, Germany
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8
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Rahman A, Latchman DS, Isenberg DA. Immunoglobulin variable region sequences of human monoclonal anti-DNA antibodies. Semin Arthritis Rheum 1998; 28:141-54. [PMID: 9872475 DOI: 10.1016/s0049-0172(98)80031-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Anti-DNA antibodies are believed to be important in the pathogenesis of systemic lupus erythematosus (SLE). Antibodies that bind specifically and with high affinity to dsDNA are most closely involved in tissue damage. Analysis of the sequences of the variable regions of human monoclonal anti-DNA antibodies is useful in defining the structural features that give rise to these binding properties. This article systematically reviews the evidence derived from such sequences. METHOD Previous reviews of this subject have been hampered by incomplete knowledge of the human immunoglobulin variable region repertoire. In this article, the original sequence data from reports of over 50 human monoclonal antibodies (mAb) are reinterpreted by alignment to the most similar alleles of the most similar germline genes. This allows accurate estimation of the site and nature of somatic mutations. RESULTS Human IgG monoclonal anti-DNA antibodies generally carry more mutations than IgM. In many cases these have been selected by an antigen-driven process. In many of the more specific, higher affinity dsDNA binders, there is an accumulation of basic residues in the complementarity determining regions. However, many exceptions to this rule exist, particularly among IgM mAb. CONCLUSIONS Unlike murine anti-DNA antibodies, these human mAb show little evidence for preferential use of particular V(H), V(K) and V(lambda) genes or families to encode antibodies of this specificity.
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Affiliation(s)
- A Rahman
- Centre for Rheumatology, Department of Medicine, University College, London, UK
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9
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Ravirajan CT, Rahman MA, Papadaki L, Griffiths MH, Kalsi J, Martin AC, Ehrenstein MR, Latchman DS, Isenberg DA. Genetic, structural and functional properties of an IgG DNA-binding monoclonal antibody from a lupus patient with nephritis. Eur J Immunol 1998; 28:339-50. [PMID: 9485213 DOI: 10.1002/(sici)1521-4141(199801)28:01<339::aid-immu339>3.0.co;2-c] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Antibodies binding to double-stranded (ds) DNA are strongly associated with renal involvement in patients with systemic lupus erythematosus (SLE). We have generated two new IgG DNA-binding monoclonal antibodies (mAb), RH-14 and DIL-6, from the peripheral blood lymphocytes of two SLE patients with glomerulonephritis using the heteromyeloma cell line CB-F7. RH-14 is an IgG1 lambda antibody which also bound to single-stranded DNA, histones and nucleosomes. DIL-6 is an IgG3 lambda antibody with restricted antigen binding specificity. cDNA encoding the variable regions of the heavy (V(H)) and light (V(L)) chains of RH-14 was sequenced and the antigen binding site of this mAb was computer modelled. Sequence analysis of V(H) and V(L) regions of RH-14 showed that V(H) is derived from germ-line gene V3-7, a member of the V(H)3 family, and V(L) is derived from DPL 11, a member of the V(lambda)2 family. Somatic mutations and basic amino acid residues are identified in the complementarity-determining regions of both V(H) and V(L) regions. The nephritogenic properties of these mAb were analyzed by implanting and growing the hybridoma cells secreting the mAb in the peritoneum of SCID mice. The animals that received the RH-14 hybridoma produced higher levels of proteinuria (3 to > or = 4) (p < 0.001) compared to the groups that received DIL-6 (trace to > or = 1) or CB-F7 (trace). Electron microscopy of kidney sections from all the RH-14-implanted animals showed granular immunoglobulin deposition in the renal glomerular capillaries and mesangium. In this study we have shown for the first time using electron microscopy that a human IgG anti-dsDNA mAb, RH-14, is nephritogenic and that deposition of such an antibody alone is sufficient to induce renal damage.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Antinuclear/chemistry
- Antibodies, Antinuclear/genetics
- Antibodies, Antinuclear/immunology
- Antibodies, Antinuclear/isolation & purification
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/genetics
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/isolation & purification
- Antibody Affinity
- Antibody Specificity
- Antigen-Antibody Reactions
- Autoimmune Diseases/immunology
- Base Sequence
- Binding, Competitive
- DNA/immunology
- DNA, Complementary/genetics
- DNA, Single-Stranded/immunology
- Female
- Genes, Immunoglobulin
- Humans
- Hybridomas/transplantation
- Immunoglobulin G/chemistry
- Immunoglobulin G/genetics
- Immunoglobulin G/immunology
- Immunoglobulin G/isolation & purification
- Immunoglobulin Heavy Chains/genetics
- Kidney/immunology
- Kidney/ultrastructure
- Lupus Nephritis/immunology
- Lupus Nephritis/pathology
- Mice
- Mice, SCID
- Microscopy, Electron
- Models, Molecular
- Molecular Sequence Data
- Protein Conformation
- Proteinuria/etiology
- Sequence Alignment
- Sequence Homology, Nucleic Acid
- Structure-Activity Relationship
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Affiliation(s)
- C T Ravirajan
- Department of Medicine, University College London, GB.
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10
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Isenberg DA, Ravirajan CT, Rahman A, Kalsi J. The role of antibodies to DNA in systemic lupus erythematosus--a review and introduction to an international workshop on DNA antibodies held in London, May 1996. Lupus 1997; 6:290-304. [PMID: 9296771 DOI: 10.1177/096120339700600316] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
MESH Headings
- Animals
- Antibodies, Antinuclear/chemistry
- Antibodies, Antinuclear/classification
- Antibodies, Antinuclear/genetics
- Antibodies, Antinuclear/immunology
- Antibody Affinity
- Antibody Diversity
- Antibody Specificity
- Autoimmune Diseases/genetics
- Autoimmune Diseases/immunology
- Clone Cells/immunology
- Cloning, Molecular
- Crystallography, X-Ray
- DNA/immunology
- Disease Models, Animal
- Gene Expression Regulation
- Genes, Immunoglobulin
- Humans
- Immunoglobulin Variable Region/genetics
- Lupus Erythematosus, Systemic/genetics
- Lupus Erythematosus, Systemic/immunology
- Lupus Nephritis/immunology
- Magnetic Resonance Spectroscopy
- Mice
- Mice, Inbred MRL lpr
- Mice, Inbred NZB
- Mutagenesis, Site-Directed
- Mutation
- Transfection
- fas Receptor/physiology
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Affiliation(s)
- D A Isenberg
- Department of Medicine, University College, London, UK
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11
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Menon S, Rahman MA, Ravirajan CT, Kandiah D, Longhurst CM, McNally T, Williams WM, Latchman DS, Isenberg DA. The production, binding characteristics and sequence analysis of four human IgG monoclonal antiphospholipid antibodies. J Autoimmun 1997; 10:43-57. [PMID: 9080299 DOI: 10.1006/jaut.1996.0106] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Antiphospholid antibodies (APL) have a notable association with recurrent miscarriages, arterial and venous thrombosis and thrombocytopenia. Analysis of the potential pathogenic effects of such human antibodies has been hampered by the considerable difficulty in producing IgG as opposed to IgM monoclonal immunoglobulins. We have developed four human monoclonal IgG APL (LJ1, AH2, DA3 and UK4) by fusing the peripheral blood lymphocytes of three patients with SLE with a mouse human heteromyeloma cell line, CB-F7. These antibodies bind to a variety of anionic phospholipids, two (LJ1 and AH2) bind total histones but none binds to ssDNA or dsDNA. Binding to beta 2 GPI is non-specific. UK4 alone demonstrates lupus anticoagulant activity. All four have lambda light chains, two are IgG1 (AH2 and UK4) and two are IgG3 (LJ1 and DA3). These APL utilize VH genes present in the fetally restricted repertoire and multiple somatic mutations in the CDR suggest an antigen-driven process. In contrast, there is no restriction in V lambda gene usage and only one lambda chain is extensively mutated. Two clonally related hybridomas were isolated from a single patients. This supports the theory that clonal expansion is the mechanism whereby antigen selects high affinity mutations.
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Affiliation(s)
- S Menon
- Bloomsbury Rheumatology Unit/Division of Rheumatology, Department of Medicine, University College, London
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12
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Williams WM, Isenberg DA. A cross-sectional study of anti-DNA antibodies in the serum and IgG and IgM fraction of healthy individuals, patients with systemic lupus erythematosus and their relatives. Lupus 1996; 5:576-86. [PMID: 9116700 DOI: 10.1177/096120339600500604] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Sera from healthy individuals, relatives of lupus patients, and lupus patients with active disease and in remission were screened for IgG and IgM antibodies to ssDNA and dsDNA. The serum samples were also separated into IgG and IgM fractions which were screened for DNA reactivity at dilutions equivalent to those used for testing un-fractionated serum. The results show that whilst, as expected, antibodies of IgG or IgM isotype to both ss and dsDNA could be detected in high concentration in the serum of lupus patients with active disease, anti-ssDNA antibodies of the IgG or IgM isotype are also detectable in healthy individuals, relatives and spouses of lupus patients. Furthermore when IgG and IgM serum fractions were separated and screened for DNA reactivity, the IgM fraction in the healthy individuals frequently showed an increase in the level of binding to ssDNA compared to the serum or separated IgM fraction of SLE relatives. In contrast no increase in DNA reactivity of the IgG fraction was detected in the separated IgG fraction from healthy individuals. These observations infer that IgM autoantibodies are present in healthy individuals at levels higher than is reported normally, and at levels comparable with those found in relatives of SLE patients in which autoreactive antibodies are frequently reported, and their ability to bind ssDNA in whole serum is inhibited by IgG antibodies present within whole serum.
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Affiliation(s)
- W M Williams
- Department of Medicine, University College London, UK
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13
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Kalsi JK, Martin AC, Hirabayashi Y, Ehrenstein M, Longhurst CM, Ravirajan C, Zvelebil M, Stollar BD, Thornton JM, Isenberg DA. Functional and modelling studies of the binding of human monoclonal anti-DNA antibodies to DNA. Mol Immunol 1996; 33:471-83. [PMID: 8676898 DOI: 10.1016/0161-5890(95)00138-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The relationships between the antigen-binding specificities of four human monoclonal anti-DNA antibodies and the structural aspects of the combining sites of two of these were examined. Competition ELISAs were used to examine the reactivities of two IgM MAbs (WRI-176 and RT-79) and two IgG mAbs (D5 and B3) to a wide range of polynucleotides. The mAbs WRI-176 and RT-79 were found to bind predominantly ssDNA, with a preference for poly (dT), whilst D5 and B3 bound components of both ss- and dsDNA, and Z-DNA. The mAb B3 also exhibited a preference for A(T) rich nucleotides. Computer models were generated for the Fv regions of WRI-176 and B3. Models for RT-79 and D5 were not generated as the structure of the long CDR-H3 loops in these mAbs could not be predicted. The B3 combining site contains a groove flanked by three arginines at positions CDR-L1-27A, CDR-L2-54 and CDR-H2-53. Using interactive molecular graphics, B-DNA was docked into the B3 antigen combining site along the plane of the VH/VL interface, whilst Z-DNA was best-fitted at approximately 90 degrees to this direction. The models provide a hypothesis to explain the ability of a single autoantibody to bind two different antigens. In addition, aspects of the base specificity of B3 may be explained. The model of the WRI-176 Fv region revealed a relatively flat surface, on which a large number of hydrophobic and aromatic residues were present. Trp-H52, in particular, is prominent on the surface. This may participate in ssDNA binding through base stacking interactions. The models allow identification of potential targets for site-directed mutagenesis.
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Affiliation(s)
- J K Kalsi
- Bloomsbury Rheumatology Unit, Department of Medicine, University College London, U.K
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14
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Menon S, Isenberg DA. Fetal calf serum in growth medium obscures the detection of early anticardiolipin antibody secreting clones. J Immunol Methods 1995; 186:65-70. [PMID: 7561149 DOI: 10.1016/0022-1759(95)00134-v] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have examined the effect of fetal calf serum (FCS) on the detection of early anticardiolipin antibody (ACL) secreting clones, using two well-established human IgG clones, LJ1 and AH2. By plating cells at 50/well and growing both clones simultaneously in standard growth (SG) medium containing 10% FCS, and in serum-free (SF) medium, we were able to measure by ELISA the total IgG and ACL levels in the supernatants. The mean OD values (x 1000) against cardiolipin for both LJ1 and AH2 were significantly higher for clones grown in SF than in SG medium: 331 OD units vs. 172, and 275 OD units vs. 166 respectively (p < 0.001). Importantly, the number of wells in which the OD value was > 0.25 units above background was: for LJ1 in SG only 3/36 vs. 30/36 in SF; similarly, for AH2 1/36 in SG vs. 22/36 in SF. In comparison, the total IgG assay using an OD value > 0.7 units above background, detected immunoglobulin secretion in all but one of the wells. We conclude that in ELISA procedures FCS in SG medium competes with solid phase cardiolipin for antibody binding. We suggest that these antibodies are binding to phospholipid from microvesicles found in FCS. We recommend that minimally 'positive' clones on testing should be re-tested and, if necessary, switched to SF medium in order to prevent such clones from being discarded prematurely.
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Affiliation(s)
- S Menon
- Department of Medicine, University College London Medical School, UK
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15
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Kalsi JK, Ravirajan CT, Wiloch-Winska H, Blanco F, Longhurst CM, Williams W, Chapman C, Hillson J, Youniou P, Latchman D. Analysis of three new idiotypes on human monoclonal autoantibodies. Lupus 1995; 4:375-89. [PMID: 8563732 DOI: 10.1177/096120339500400508] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have identified and characterised three new idiotypes on human IgM McAbs generated from the splenocytes of a SLE patient with active disease. RT-6, which binds H1 and Sm/RNP, expresses essentially a private Id. Its expression is limited to a small number of human McAbs and the sera from patients with infectious diseases. In contrast RT-72Id and RT-84Id, expressed on McAbs which are polyreactive for two or more antigens, have a public distribution. RT-72Id and RT-84Id are found on McAbs from murine and human adult, and foetal tissues. In sera, significant numbers of SLE, RA and patients with other autoimmune diseases are positive for both Ids. RT-84Id is also elevated in SLE relatives and spouses, and in patients with Klebsiella infection. No correlation with disease activity, IgM or IgG levels was observed with either Id. However, RT-72Id was significantly associated with anti-ssDNA antibodies and RhF. RT-6Id and RT-72Id are located on the framework regions of the mu heavy chain, whereas RT-84Id is present on the kappa light chain, within the binding site. The McAbs are encoded by mainly germline genes: heavy chains of RT-6, RT-72 and RT-84 are encoded by the genes VH26, VH4.22 and VH4.21, respectively, and the light chain sequences of RT-6 and RT-72 are derived from DPL11 and HK102. Immunofluorescent staining revealed the presence of RT-72Id and RT-84Id positive immunoglobulin deposits in 18% and 45%, respectively, of the lupus renal sections compared with none in the disease control group, suggesting that these Ids may contribute to the pathology of the disease.
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Affiliation(s)
- J K Kalsi
- Department of Rheumatology Research, Bloomsbury Rheumatology Unit, London, UK
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16
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Abstract
Ubiquitin is the most phylogenetically conserved protein known. This 8,500 Da polypeptide can be covalently attached to cellular proteins as a posttranslational modification. In most cases, the addition of multiple ubiquitin adducts to a protein targets it for rapid degradation by a multisubunit protease known as the 26S proteasome. While the ubiquitin/26S proteasome pathway is responsible for the degradation of the bulk of cellular proteins during homeostasis, it may also be responsible for the rapid loss of protein during the programmed death of certain cells, such as skeletal muscle during insect metamorphosis. In addition, alterations in the expression and regulation of ubiquitin may play significant roles in pathological disorders. For example, dramatic increases in ubiquitin and ubiquitin-protein conjugates are observed in a wide variety of neurodegenerative disorders, including Alzheimer's disease. Patients suffering from the autoimmune disease systemic lupus erythematosus generate antibodies reacting with ubiquitin and ubiquitinated histones. At present, it is not known whether these changes in ubiquitin expression and regulation initiate pathological changes in these diseases or if they are altered as a consequence of these disorders.
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Affiliation(s)
- S Muller
- Institut de Biologie Moléculaire et Cellulaire, UPR 9021 CNRS, Strasbourg, France
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17
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Ravirajan CT, Harmer I, McNally T, Hohmann A, Mackworth-Young CG, Isenberg DA. Phospholipid binding specificities and idiotype expression of hybridoma derived monoclonal autoantibodies from splenic cells of patients with systemic lupus erythematosus. Ann Rheum Dis 1995; 54:471-6. [PMID: 7632089 PMCID: PMC1009905 DOI: 10.1136/ard.54.6.471] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE To analyse the phospholipid binding specificity, functional characteristics and idiotype expression of human hybridoma derived monoclonal autoantibodies (MAb) derived from the spleens of two patients with active systemic lupus erythematosus (SLE). METHODS The IgM MAbs binding to phospholipids were generated from spleen cells of two patients (RSP and RT) with active SLE and their specificity of binding to neutral phospholipids (phosphatidyl ethanolamine, phosphatidyl choline, platelet activating factor, sphingomyelin) and negatively charged phospholipids (phosphatidyl glycerol, phosphatidyl serine, phosphatidic acid, phosphatidyl inositol and cardiolipin (CL)) analysed. Binding specificity of cross reactive antibodies (those binding to CL and DNA) was confirmed by fluid phase inhibition assays. Lupus anticoagulant activity and beta 2-glycoprotein-1 (beta 2 GP-1) requirement for the antigen binding of these MAbs were detected using the modified dilute Russell's viper venom test and modified anti-CL enzyme linked immunosorbent assay (ELISA), respectively. Expression of idiotypes (Id) Id RT-84 and Id H3 was analysed using rabbit polyclonal and murine monoclonal anti-idiotype reagents, respectively. RESULTS Twelve clones from the patient RSP and eight clones from patient RT were reactive with phospholipids. Marked differences in phospholipid binding of these MAbs were noted, varying from truly polyreactive (RT-72 bound to most phospholipids tested) to monospecific (RT-84 bound only to CL). Furthermore, MAbs RT-84, RT-129, and RSP-57 had lupus anticoagulant activity and required beta 2 GP-1 for CL binding. It was found that 75% of phospholipid binding antibodies from RT clones expressed RT-84 Id, but none from RSP clones did so, and that Id H3 was expressed only by the RT-83 antibody. CONCLUSION These results show that human anti-phospholipid MAbs are heterogeneous with respect to phospholipid binding, functional characteristics, and Id expression.
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Affiliation(s)
- C T Ravirajan
- Bloomsbury Rheumatology Unit, Department of Medicine, University College, London, United Kingdom
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18
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Ichikawa K, Khamashta MA, Koike T, Matsuura E, Hughes GR. beta 2-Glycoprotein I reactivity of monoclonal anticardiolipin antibodies from patients with the antiphospholipid syndrome. ARTHRITIS AND RHEUMATISM 1994; 37:1453-61. [PMID: 7945470 DOI: 10.1002/art.1780371008] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE To elucidate the specificity of anticardiolipin antibodies (aCL) from patients with the antiphospholipid syndrome (APS) to various phospholipids (PLs), DNA, and beta 2-glycoprotein I (beta 2-GPI). METHODS Five monoclonal aCL were established from peripheral blood lymphocytes of 3 patients with the APS. The reactivity of monoclonal aCL with various PLs, with DNA, and with beta 2-GPI was examined by enzyme-linked immunosorbent assay (ELISA). RESULTS All of the monoclonal aCL bound to anionic PLs, only in the presence of beta 2-GPI. Neither monoclonal aCL nor beta 2-GPI bound to DNA. Monoclonal aCL bound to solid-phase beta 2-GPI on polystyrene ELISA plates that had carboxyl groups on their surface, but did not react with solid-phase beta 2-GPI on ordinary polystyrene plates. A mixture of beta 2-GPI and CL inhibited the binding of monoclonal aCL to beta 2-GPI, but CL or beta 2-GPI alone did not. CONCLUSION Monoclonal aCL may recognize a cryptic epitope, which appears as a result of beta 2-GPI binding to anionic PLs or to polystyrene with carboxyl groups.
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Affiliation(s)
- K Ichikawa
- The Rayne Institute, St. Thomas' Hospital, London, UK
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19
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Tuaillon N, Watts RA, Isenberg DA, Muller S. Sequence analysis and fine specificity of two human monoclonal antibodies to histone H1. Mol Immunol 1994; 31:269-77. [PMID: 7511211 DOI: 10.1016/0161-5890(94)90124-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Two human IgM lambda monoclonal antibodies (MAb) derived from the splenic lymphocytes of patients with idiopathic thrombocytopenia (Ben) and systemic lupus erythematosus (Wri) were studied. BEN-27 and WRI-170 hybridoma supernatants were screened for binding to ssDNA, dsDNA, poly (ADP-ribose), cardiolipin, histone subclasses and Klebsiella K30 cell wall antigen. Of this panel of antigens, BEN-27 and WRI-170 antibodies reacted only with histone H1. Their fine specificity was defined by direct and inhibition ELISA with synthetic peptides of the major human H1b variant. Antibody WRI-170 was shown to bind to both the N- and C-terminal peptides encompassing residues 1-16 and 204-218 of H1b whereas BEN-27 reacted only with peptide 204-218. To analyse the genetic origin of these autoantibodies, we determined the nucleotide sequence of the heavy (H) and light (L) chain variable regions of these two hybridomas. BEN-27 and WRI-170 MAbs were found to use VH1-DN1-JH4/V lambda 3-J lambda 2 and VH3-DIR2-D21/9-JH1/V lambda 2-J lambda 2 gene segment combinations respectively. Between 70 and 95% homology was demonstrated when the mRNA sequences for BEN-27 and WRI-170 were compared with published VH and V lambda germline sequences. This finding suggests that BEN-27 heavy and light chains and WRI-170 light chain use unidentified VH and V lambda germline gene segments whereas WRI-170 heavy chain derives from a VH gene segment recently identified. It is noteworthy that the CDRs of the two MAbs contain several negatively charged amino acids which are assumed to be of critical importance in antigen binding. Moreover, striking similarities are observed between BEN-27 heavy chain CDR2 and a previously described murine anti-H1 Ab heavy chain CDR2.
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Affiliation(s)
- N Tuaillon
- Laboratoire d'Immunochimie, UPR 9021 CNRS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France
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Blanco F, Longhurst C, Watts R, Kalsi J, Wiloch HW, Youinou P, Latchman DS, Isenberg DA. Identification and characterization of a new human DNA reactive monoclonal antibody and a common idiotype, WRI 176 Id beta. Lupus 1994; 3:15-24. [PMID: 8025580 DOI: 10.1177/096120339400300105] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We describe a human monoclonal antibody designated WRI 176 beta and a common idiotype that it carries. This antibody was derived from the spleen of a patient with SLE. WRI 176 is an IgM kappa monoclonal reacting with ssDNA, dsDNA, poly(dT) and it is likely that mAb WRI 176 beta is a representative of the so-called natural autoantibodies. The common Id designated WRI 176 Id beta is located on the heavy chain of the mAb WRI 176 beta molecule and appears to be located outside the binding site. Sequence analysis of the WRI 176 beta heavy chain showed it to be highly homologous (97.3%) with a germline gene 56PI derived from a human fetus. In a retrospective analysis, although 44% of SLE patients had raised levels of the WRI 176 beta no correlation was found with the activity of the disease. The idiotype was also expressed frequently in a range of autoimmune rheumatic and infectious diseases and in some healthy first-degree relatives of SLE patients.
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Affiliation(s)
- F Blanco
- Bloomsbury Rheumatology Unit, Department of Medicine, University College London Medical School, UK
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21
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Ehrenstein M, Longhurst C, Isenberg DA. Production and analysis of IgG monoclonal anti-DNA antibodies from systemic lupus erythematosus (SLE) patients. Clin Exp Immunol 1993; 92:39-45. [PMID: 8385586 PMCID: PMC1554857 DOI: 10.1111/j.1365-2249.1993.tb05945.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
This study compares recently devised methods for producing IgG anti-DNA MoAbs from patients with SLE and analyses the antibodies generated from one patient at different phases of disease. Lymphocytes from SLE patients were transformed with Epstein-Barr virus(EBV) and/or fused with a heteromyeloma cell line, CB-F7. Direct fusion with CB-F7 resulted in the highest proportion of IgG-secreting lines, whereas EBV transformation resulted in a high percentage of IgM-secreting lines. Using direct fusion, five IgM anti-DNA antibody-secreting hybridomas were generated using lymphocytes from a patient with relatively inactive SLE. Six months later when the disease was active, only IgG anti-DNA antibodies were produced. The antigen-binding patterns of the MoAbs were analysed. Only one of the IgM anti-DNA antibodies reacted with dsDNA by ELISA and none by Crithidia immunofluorescence, whereas two of the IgG antibodies reacted with dsDNA by ELISA and Crithidia but did not bind to ssDNA. Only the two IgG high affinity anti-dsDNA antibodies bound to histones, and this was enhanced by added DNA, whereas three IgM antibodies bound to cardiolipin. This study supports the notion that MoAbs derived from a patient with SLE represent those found in the serum of SLE patients at different stages of disease activity. The binding to histones by the two IgG anti-dsDNA antibodies supports the recently expressed view that antibodies binding DNA/histone may be important in the pathogenesis of SLE.
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Affiliation(s)
- M Ehrenstein
- Department of Rheumatology Research, University College and Middlesex Hospital Medical School (UCMSM), London, UK
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22
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Affiliation(s)
- B Diamond
- Department of Microbiology, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461
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