Search PubMed⌕ Search

Biomedical subjects

B Diamond

Publications and source records attributed to B Diamond.

At least 109 records · Page 6Linked to original sources
PubMed1991

Molecular characteristics of antibodies bearing an anti-DNA-associated idiotype.

Anti-double-stranded DNA antibodies are the hallmark of the disease systemic lupus erythematosus and are believed to contribute to pathogenesis. While a large number of anti-DNA antibodies from mice with lupus-like syndromes have been characterized and their variable region genes sequenced, few human anti-DNA antibodies have been reported. We describe here the variable region gene sequences of eight antibodies produced by Epstein-Barr virus (EBV)-transformed B cells that bear the 3I idiotype, an idiotype expressed on anti-DNA antibodies and present in high titer in patients with systemic lupus. The comparison of these antibodies to the light chains of 3I+ myeloma proteins and serum antibodies reveals that EBV transformation yields B cells producing antibodies representative of the expressed antibody repertoire. The analysis of nucleotide and amino acid sequences of these antibodies suggests the first complementarity determining region of the light chain may be important in DNA binding and that paradigms previously generated to account for DNA binding require modification. The understanding of the molecular genetics of the anti-DNA response requires a more complete description of the immunoglobulin germ line repertoire, but data reported here suggest that somatic diversification is a characteristic of the anti-DNA response.

Amino Acid Sequence↗
PubMed1991

Characterization of the human Ig V lambda II gene family and analysis of V lambda II and C lambda polymorphism in systemic lupus erythematosus.

We report the cDNA sequence of an expressed human V lambda II gene and present an RFLP analysis of the Ig gene family defined by this clone. This V lambda II gene was expressed in a monoclonal B cell line generated from a patient with SLE by transformation with EBV. The encoded lambda L chain displays the 8.12 Id, an Id common to anti-DNA antibodies from patients with SLE. Using a coding region probe we estimate from Southern blot analysis that the germline V lambda II gene family contains at least 15 members. Many of the V lambda II restriction fragments are polymorphic both in SLE patients and in nonautoimmune individuals. EcoRI, HindIII, and TaqI RFLP analyses of the V lambda II gene family and EcoRI analysis of the C lambda gene family reveal no polymorphisms specific to SLE. Observed V lambda II and C lambda allele frequencies are the same among SLE patients and nonautoimmune individuals, and show no evidence of linkage disequilibrium between the two loci.

Alleles↗
PubMed1991

A novel class of anti-DNA antibodies identified in BALB/c mice.

We have characterized four IgG monoclonal antibodies (mAbs) derived from BALB/c mice that bind double-stranded DNA (dsDNA) with high affinity. The hydridomas were selected for expression of a member of the VHS107 family. Three of the four cell lines use the VH11 gene and one uses the VH1 gene. These antibodies exhibit many characteristics of pathogenic anti-DNA antibodies. They are high affinity and not broadly crossreactive. Unlike the anti-DNA antibodies in autoimmune mice, they exhibit no somatic mutation in their VH genes. These results demonstrate that somatic mutation of VHS107 genes is not necessary for generating high affinity dsDNA binding. The fact that such antibodies have not previously been reported suggests that they are rare and that their expression may be downregulated in both nonautoimmune and autoimmune individuals.

Amino Acid Sequence↗
PubMed1991

Alteration of the T-cell receptor repertoire in A.CA mice expressing an Ead transgene.

In an effort to generate an A.CA mouse expressing Ed, the Ead gene has been introduced into A.CA mice which lack the major histocompatibility complex (MHC) class II E molecule. Flow cytometric analysis shows cell surface expression of the E alpha chain on lymphocytes and macrophages in the transgenic mice. Analysis of T-cell receptor (Tcr) genes deleted in some E-expressing mouse strains demonstrates that T cells expressing Tcrb-V5 are partially deleted in these transgenic mice while those expressing Tcrb-V8 and Tcrb-11 are not. In addition, the expressed E alpha d chain can promote Mycoplasma arthriditis mitogen (MAM)-induced T-cell proliferation. The expression of the E alpha chain, presumably as an A beta fE alpha d heterodimer, can alter the peripheral T-cell repertoire and T-cell reactivity to a microbial superantigen.

Animals↗
PubMed1991

Antibodies elicited by pneumococcal antigens bear an anti-DNA--associated idiotype.

There is evidence in both murine and human lupus that the production of anti-DNA antibodies may be triggered by environmental antigens. To explore this further, we studied the serum of 10 nonautoimmune individuals immunized with a polyvalent pneumococcal polysaccharide vaccine. All 10 patients showed a rise in the titer of antipneumococcal antibodies bearing an anti-DNA-associated idiotype. The antipneumococcal response was specific as no idiotypic antitetanus antibodies were detected. Furthermore, no anti-DNA antibodies were present in postvaccination sera. The molecular analysis of antipneumococcal and anti-DNA antibodies bearing a common idiotype will help elucidate how foreign antigen might lead to the production of anti-DNA antibodies in susceptible individuals.

Antibodies, Antinuclear↗
PubMed1990

Staphylococcus aureus infection of human endothelial cells potentiates Fc receptor expression.

Vasculitis, a recognized complication of staphylococcal-endovascular infections, may result in part, from the expression of FcR by Staphylococcus aureus-infected endothelial cells. FcR were measured using [51]Cr labeled SRBC preincubated with rabbit anti-SRBC IgG. FcR were not detected on uninfected endothelial cells, but were demonstrated on S. aureus infected cells using IgG, but not IgM labeled SRBC. FcR expression was dependent on the initial bacterial density (greater than or equal to 8 x 10(7) cfu/ml) and on phagocytosis of the staphylococci, but not on new protein synthesis. IgG labeled SRBC binding was blocked by aggregated IgG but not IgM. SRBC coated with the F(ab')2 portion of IgG did not bind, thus confirming that FcR were specifically involved in this interaction. FcR are expressed after S. aureus invasion of human endothelial cells and may contribute to the vasculitis which often accompanies S. aureus-endovascular infections.

Cells, Cultured↗
PubMed1990

Identification of a new V kappa gene family that is highly expressed in hybridomas from an autoimmune mouse strain.

We have identified a new murine V kappa family that contains five to seven members, one member of which encodes the L chain V region of an anti-dsDNA antibody produced by a BALB/c hybridoma, C8.5. The cloned C8.5 V kappa gene exhibits highest homology with a human V kappa gene that was cloned from a nonproductive rearrangement but has never been seen in an expressed repertoire. Because this family was first identified in an autoantibody, we studied its expression in an autoimmune mouse strain. This V kappa family is expressed in 20% of hybridomas from NZB mice.

Amino Acid Sequence↗
PubMed1990

Genetic recombination in the alpha 2 domain of the E alpha chain yields an Ed molecule with altered T cell activation.

We have used a novel T cell selection strategy to isolate a mutant of an H-2d/f murine macrophage line defective in its ability to present antigen to some Ed-restricted helper T cells. This mutant has an amino acid substitution in the alpha 2 domain of the Ed molecule. The mutation changes the sequence at codon 177 from ACC to CAC, which results in a threonine to histidine substitution and appears to be the first in vitro mutation to have arisen by genetic recombination. Even though the mutation is distal to the proposed antigen-binding groove, it affects antigen presentation, presumably by altering the scaffolding for the antigen-binding groove. This type of mutant might not be readily isolated using other selection techniques.

Amino Acid Sequence↗
PubMed1990

Comparison of DNA antibody idiotypes in human sera: an international collaborative study of 19 idiotypes from 11 different laboratories.

The distribution of and relationships between 18 anti-DNA antibody idiotypes and one anti-acetylcholine receptor antibody idiotype have been tested in an international collaborative study of human sera from 180 individuals. The main finding is that the serum levels of many of these idiotypes, whether of murine or human origin, show a high degree of statistical correlation. The studies in a wide range of autoimmune rheumatic diseases confirm that none of the idiotypes tested is disease specific, but 13 of 15 (87%) whose levels were recorded as OD units or cpm correlated strongly with anti-ssDNA antibody levels and 11 of 15 (73%) with total serum IgM. Expression of several idiotypes was found to fluctuate in parallel with disease activity in SLE; levels of others were also elevated in the healthy relatives of lupus patients whilst a few were also raised in the spouses of these patients. The data support the notion that there may be only a few groups of related DNA antibody idiotypes. The correlations between the idiotypes with regard to their quantities, association with disease activity, and wide distribution in different diseases and healthy individuals suggest at least two explanations. First, all of these idiotypes may be present in normal immunoglobulin repertoires and simply increase in response to poly- or oligoclonal B-cell activation in autoimmune diseases. Secondly, these idiotypes may be structurally linked to each other, so that their behaviour under conditions of specific antigenic stimulation is similar. Genetic and structural studies will be required to distinguish between these possibilities.

Autoantibodies↗
PubMed1990

Comparative study of idiotypes on monoclonal antibodies derived from patients with lupus and leprosy and from normal individuals.

A collaborative study was performed to compare the expression of a series of idiotypes defined on human anti-DNA and other autoantibodies. Three panels of human monoclonal antibodies were tested: eight derived from patients with systemic lupus erythematosus (SLE); 13 from an individual with lepromatous leprosy; and 38 from normal subjects. The following rabbit anti-idiotype sera were used: one (RId16/6) raised against the lupus-derived monoclonal anti-DNA antibody 16/6, four (RId8E7, RId4G7, RId4D5 and RIdTH9) against leprosy-derived monoclonal antibodies of various specificities, and one (anti-4.6.3) against a normal-derived anti-DNA monoclonal (KIM 4.6). In addition, two other anti-idiotypes were used--one a murine monoclonal (3I), the other a rabbit polyclonal (RIdD)--which had been raised against polyclonal anti-DNA antibodies from lupus serum. Further experiments were performed with immunoabsorbed fractions of RId8E7. Direct-binding and competition assays were used. All of the anti-idiotypes produced different patterns of positivity among the three panels of human monoclonal antibodies, with the exception of RId8E7 and RId4G7, which showed considerable concordance. There was a tendency towards anti-idiotypes being disease- or group-specific: thus anti-4.6.3 failed to bind to any of the lupus or leprosy-derived monoclonals, while RId16/6 and RId8E7 bound most strongly to the lupus- and leprosy-derived antibodies respectively. KIM 4.6 itself was bound only weakly by RId16/6, while 16/6 was not recognized by anti-4.6.3; 16/6 was, however, bound by 3I, while KIM 4.6 was not. 3I bound to several other monoclonals but RIdD, which has been shown to be specific for the anti-DNA fraction of lupus serum, did not bind to any of them. These results indicate that the majority of these anti-idiotype preparations recognize largely separate sets of determinants. The monoclonal antibodies which bind to DNA may be only partly representative of anti-DNA antibodies in the serum of lupus patients.

Antibodies, Anti-Idiotypic↗
PubMed1990

A murine macrophage line of the H-2d/f haplotype can activate H-2k suppressor T cells.

Little is known about the molecular basis for activation of suppressor T cells. In this report we describe two macrophage cell lines, BAC1.2.SC8 and its variant progeny B26, that differ in their ability to activate suppressor T cells. The SC8 line is derived from a (BALB/c x A.CA)F1 (H-2d/f) mouse and is haploid with respect to I-Ed. It is capable of activating I-Ed-restricted helper T cells as well as poly-(Glu50Tyr50)-specific I-Ed-restricted suppressor cells. The B26 variant can activate H-2d-restricted helper T cells but activates H-2k-restricted suppressor cells. The I-Ed molecules of SC8 and of B26 have identical amino acid sequences. This suggests that suppressor T cells either recognize posttranslational modifications of the I-E molecule or that there is another accessory molecule that helps determine the major histocompatibility complex restriction in the activation of suppressor T cells.

Animals↗
PubMed1990

Molecular characterization of a somatically mutated anti-DNA antibody bearing two systemic lupus erythematosus-related idiotypes.

We report the molecular characterization of 2A4, an IgG, DNA-binding antibody bearing the 3I and F4 idiotypes which are associated with anti-DNA antibodies in serum of patients with systemic lupus erythematosus (SLE). The antibody is produced by an EBV-transformed B cell line derived from a patient with multiple myeloma whose myeloma protein is also an IgG, 3I-reactive, F4-reactive, DNA-binding immunoglobulin, although the 2A4 antibody does not itself represent the myeloma protein. The 2A4 heavy chain is encoded by a VH4 gene, a D-D gene fusion and the JH6 gene; the light chain is derived from a Vk1 gene and the Jk2 gene. This is the first human antibody shown to have a CDR3 encoded by a D-D fusion. DNA sequence analysis of the 2A4 VH gene together with a Southern blot of genomic DNA probed with a 2A4 VH-specific oligonucleotide strongly suggest it to be somatically mutated. The data provide evidence that human autoantibodies can be products of somatically mutated genes and suggest that the 2A4 antibody may reflect the selective pressure of antigen.

Amino Acid Sequence↗
PubMed1990

Pathogenic anti-DNA antibodies in SLE: idiotypic families and genetic origins.

We have adopted an idiotypic approach to study the double stranded DNA (dsDNA) binding antibodies of systemic lupus erythematosus (SLE). Three anti-idiotypic reagents, 8.12, 3I, and F4, identify cross reactive idiotypes that are each expressed on anti-dsDNA antibodies in the sera of many patients with SLE. These idiotypic antibodies are implicated in the pathogenesis of SLE as they are present in immune complex deposits in the kidneys of patients with SLE glomerulonephritis. The autoantibody associated idiotypes are also expressed on antibodies that do not bind DNA. We are investigating the origin of the pathogenic anti-dsDNA antibodies of SLE by comparing the autoantibodies, the antibodies to foreign antigens, and the myeloma proteins that express each SLE associated idiotype. In conjunction with serological analysis of these idiotypic systems, molecular genetic studies indicate that both the 8.12 and the 3I autoantibody associated idiotypes may be germline encoded, while the F4 idiotype is generated by somatic mutation. The data further suggest that the antigenic specificity of the pathogenic anti-DNA antibodies of SLE is acquired through somatic mutation of germline immunoglobulin genes. By studying the regulation of genes capable of encoding pathogenic autoantibodies, in both SLE patients and non-autoimmune individuals, we may be able to elucidate the pathogenesis of autoimmune disease and begin to design more effective therapeutic interventions.

Antibodies, Antinuclear↗
PubMed1989

Functional analysis of cloned macrophage hybridomas. VII. Modulation of suppressor T cell-inducing activity.

We have previously characterized a macrophage hybridoma clone, termed clone 59, which induced immunity but consistently failed to induce Ts responses. Macrophage 59 cells were cultured with supernatants from several activated T cell clones to determine if lymphokines could modulate the activity of this macrophage hybridoma to generate effector Ts. Culture supernatants from Th1 clones and from one atypical IL-4 and IFN-gamma-producing T cell clone successfully modulated clone 59 cells to induce effector Ts cells. In contrast, supernatants from activated Th2 cells failed to generate Ts-inducing activity in macrophage 59 cells. Culture with recombinant derived IFN-gamma was sufficient to cause modulation of Ts-inducing activity in macrophage 59 cells. The data imply that the differential functional activities ascribed to various macrophage hybridoma clones reflect macrophage heterogeneity instead of independent macrophage lineages. The suppression induced by clone 59 macrophages was genetically restricted to the putative I-J region. The ability of IFN-gamma containing supernatants to endow macrophage 59 with the capacity to induce effector suppressor cells was specifically abrogated by addition of an anti-IJk-idiotype antibody, which also reacts with IJ-interaction molecules, indicating that the mechanism of modulation most likely involves expression of IJ-interaction molecule determinants on antigen presenting cells.

Animals↗
PubMed1989

A cross-reactive idiotype on anti-DNA antibodies defines a H chain determinant present almost exclusively on IgG antibodies.

We have previously reported two anti-idiotypic antibodies, 3I and 8.12, that recognize L chain determinants on anti-DNA antibodies. We have generated a new anti-idiotypic antibody, F4, that recognizes a H chain determinant on cationic anti-DNA antibodies. F4 reactivity is present in high titer in serum of approximately 60% of SLE patients and on 84 of 706 myeloma proteins. It is preferentially associated with 3I reactive L chains. Furthermore, antibodies bearing both the F4 and 3I idiotypic determinants preferentially bind DNA. Amino acid sequencing of H chains isolated from four F4-reactive myeloma proteins suggests that they derive from two currently identified VH gene families. F4 reactivity is restricted almost exclusively to Ig of the IgG isotype suggesting that F4 may recognize either a somatically mutated hypervariable region or a variable region used late in the immune response. F4, therefore, represents a new idiotypic family preferentially associated with auto-Ag specificity and having features of an Ag-driven immune response.

Amino Acid Sequence↗