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D A Isenberg

Publications and source records attributed to D A Isenberg.

At least 235 records · Page 13Linked to original sources
PubMed1995

Human T cell responses to autoantibody variable region peptides.

The origins and regulation of autoantibodies in SLE may involve idiotypic cell interactions. The purpose of this study was to determine if SLE patients have T cells reactive with the idiotopes of autoantibodies. Sequences of the variable regions of two DNA-binding autoantibodies (V lambda of antibody B3 and VH of 9G4) were selected according to the predicted location of their idiotypes defined previously by anti-idiotypic antibodies. The sequences were prepared as synthetic 16mer peptides (idiopeptides). Peripheral blood mononuclear cells were prepared from SLE patients (n = 28) and controls (n = 13) and put into multiple microcultures with idiopeptide for 6 days. The frequency of responding cultures was determined as those incorporating thymidine at levels above the mean plus three standard deviations of the control cultures lacking peptide. Of the 28 lupus patients, six responded to B3 idiopeptide and five to the 9G4 idiopeptide. Some patients responded to other idiopeptides, but only one normal individual responded to each reference peptide. The difference between the patient and control responses to all idiopeptides was significant by chi 2 analysis (P = 0.025). We conclude that patients with SLE show evidence of sensitisation of T cells to idiotopes of autoantibodies. Such anti-idiotypic T cells could either provide idiotype-specific help or suppression for autoantibody responses in SLE.

Adult↗
PubMed1995

Effect of histone and histone-RNA complexes on the disease process of murine systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is characterised by the production of a variety of autoantibodies against cell surface, nuclear and cytoplasmic antigens. The antigen or antigens responsible for the induction of this disease is/are unknown. We have analysed the antigenicity and pathogenicity of free histones and histones complexed with RNA in Balb/c, B10 Br, C57BL/6 and MRL-lpr/lpr mice by giving 1 microgram and 25 micrograms of each antigen intraperitoneally in complete and incomplete Freund's adjuvant. The same number of control animals were injected with either adjuvant or PBS. In the initial experiment we gave three doses of antigen at three weekly intervals. B10 Brown and C57BL/6 mice had no response to the antigens. Balb/c mice developed a mild transient antibody response against H1 histone, branched peptide of ubiquitinated H2A (peptide T4) and also against ssDNA. However in repeated experiments when the histone-RNA complex was injected into young MRL-lpr/lpr animals at two weekly intervals, a significantly increased antibody response was detected against H1, peptide T4 and some histone peptide residues (204-218 of H1, 1-20 and 65-85 of H2A, 1-25 of H2B, 1-21 of H3 and 1-29 of H4) compared to the control groups. Moreover, this group also showed elevated serum anti-DNA antibody levels and early impairment of renal function assessed by the urine protein levels. These experiments have demonstrated that there is a genetic variation in antibody responses against histones and histone-RNA complexes and that histone-RNA complexes exaggerate the disease in young MRL-lpr/lpr mice by inducing antibodies to basic regions of histones and other autoantigens.

Animals↗
PubMed1995

Expression of a human fetal anti-DNA antibody idiotype BEG-2 beta in the families of patients with rheumatoid arthritis.

BEG-2 is a monoclonal antibody produced by the human-human hybridoma technique from a 12 weeks old human fetus. A polyclonal antiserum was raised in an (NZW x Half-lop hybrid) rabbit against BEG-2 and the anti-BEG-2 anti-idiotype was purified and characterised. Using this rabbit reagent the expression of the BEG-2 beta idiotype was analysed in 12 patients with active rheumatoid arthritis and their close family members (n = 54). Twenty five sera from healthy controls were analysed to establish a normal range. Ten of 12 patients (83%) with rheumatoid arthritis expressed the BEG-2 idiotype as well as 11 of 54 healthy unaffected relatives (20%).

Antibodies, Antinuclear↗
PubMed1995

Dual recognition of lipid A and DNA by human antibodies encoded by the VH4-21 gene: a possible link between infection and lupus.

The VH4-21 (V4-34) gene segment, a member of the VH4 family, is expressed early in B-cell maturation and is utilized by approximately 6% of normal adult B lymphocytes. This prevalence indicates an importance of VH4-21 in the B-cell repertoire. The gene also encodes certain autoantibodies being mandatory for pathological IgM anti-red cell antibodies directed against the I/i antigen, and also capable of encoding anti-DNA antibodies. Recognition of I/i antigen or DNA appears to be via two distinct sites on VH, with I/i binding mediated by sequences in the framework region, and DNA binding correlating with the presence of positively charged amino acids in complementarity-determining region 3. However, these positively charged residues appear to suppress the ability of the framework region to interact with I/i, rendering a single sequence monospecific for I/i or DNA. The IgM anti-DNA antibodies also recognize bacterial lipid A, whereas the anti-I/i antibodies do not, indicating that CDR3 may be involved in binding the negatively charged lipid A. Structural similarities between the DNA backbone and lipid A provide a possible explanation for this cross-reactivity. This dual recognition of bacterial antigen and autoantigen provides a potential link between infection and autoimmunity.

Adult↗
PubMed1995

Analysis of variable region genes encoding anti-Sm and anti-cardiolipin antibodies from a systemic lupus erythematosus patient.

We have analysed the heavy and light chain variable region genes of two monoclonal antibodies, specific for the Sm antigen (RSP1; IgG kappa) and for cardiolipin (RSP4; IgM lambda), derived from a patient with active systemic lupus erythematosus (SLE). We have established that the variable region genes of the RSP1 autoantibody are somatic mutants of two germ line genes from the VH4 and V kappa 1 gene families. RSP4 antibody uses gene segments closely related to a VH3 gene member and to a V lambda 1 gene. The presence and distribution of the somatic mutations on both monoclonal autoantibodies are compatible with an antigen-driven immune process. These data suggest that in SLE a common antigenic stimulus may govern the autoantibody response against a wide spectrum of unrelated antigens, including native DNA, cardiolipin or Sm antigens, and provide further evidence that disease-associated autoantibodies are generated through antigen-selected somatic mutations.

Adult↗
PubMed1994

Autoantibodies reacting with poly(ADP-ribose) and with a zinc-finger functional domain of poly(ADP-ribose) polymerase involved in the recognition of damaged DNA.

Poly(ADP-Ribose) polymerase (PARP) is a chromatin-associated enzyme that specifically binds to DNA strand breaks in a zinc-dependent manner. We describe here the presence of IgG antibodies reacting with recombinant human PARP in the serum of patients with systemic lupus erythematosus (SLE) and primary and secondary Sjögren's syndrome (pSS and sSS). The reactivity of patients' sera was further studied in ELISA with a synthetic peptide of 44 residues corresponding to the second zinc finger (F2) present in the DNA-binding domain of PARP and which was shown to effectively bind 65Zn. Thirty-five percent of SLE sera (n = 97), 42% of pSS sera (n = 67), and 56% of sSS sera (n = 16) were found to contain raised levels of IgG antibodies reacting with peptide F2 which corresponds to the domain in PARP that is directly involved in the specific recognition of single and double strand breaks in DNA. Antibodies reacting with the whole enzyme and/or peptide F2 occurred independently from antibodies reacting with poly(ADP-ribose) which is rapidly synthesized in vivo by PARP from NAD and then degraded in response to DNA strand breaks.

Amino Acid Sequence↗
PubMed1994

Comparison of a monoclonal and polyclonal anti-idiotype against a human IgG anti-DNA antibody.

Over the last decade a number of idiotypes (Id) have been identified on monoclonal IgM anti-DNA antibodies which represent germ-line genes. This study describes two new idiotypes present on a monoclonal human IgG anti-DNA antibody, D5 derived from a patient with active SLE. The two idiotypes, designated D5-RId and D5-MId, are defined by a polyclonal and monoclonal anti-Id respectively. Both anti-Ids inhibited each other's binding to D5 in an ELISA and did not bind to human IgG. Using western blotting the D5-RId was located on the light chain whereas the D5-MId bound to conformational determinants; both idiotypes were close to or at the binding site for DNA. The anti-Id reagents were used in ELISAs to screen human sera and tissue samples for the presence of the D5-MId and the D5-RId. The upper limit of normal for sera in the D5-MId ELISA was much lower than the D5-RId ELISA indicating a greater degree of specificity in the former. The idiotypes were found only in the IgG fraction of the sera. About 30% of SLE patients had either the D5-MId or the D5-RId and 20% had elevated levels of both, showing a considerable overlap in the expression of the two idiotypes. This overlap was also observed in the other disease groups including patients with other autoimmune diseases, though the numbers of patients expressing the idiotypes were significantly lower than in the SLE group. The idiotypes were present on both DNA binding and non-DNA binding fractions of lupus sera. D5-MId was present in 6/10 renal lupus biopsies and only in 2/15 disease control renal biopsies in which immunoglobulin was deposited. D5-RId did not stain any sections. There is a close correlation between the presence of the D5-MId and D5-RId in SLE sera and the level of expression. It is evident that both idiotypes are associated with SLE and are markers of a population of IgG anti-DNA antibodies, the isotype associated with active disease. Since the idiotypes are not found on IgM antibodies they are likely to be generated by somatic mutation.

Animals↗
PubMed1994

Sequence analysis and fine specificity of two human monoclonal antibodies to histone H1.

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.

Amino Acid Sequence↗
PubMed1994

Detection of autoantibodies to the 90 kDa heat shock protein in systemic lupus erythematosus and other autoimmune diseases.

Expression of the highly conserved 90 kDa heat shock protein (Hsp90) is elevated in the peripheral blood mononuclear cells of approximately 25% of patients with SLE. Conflicting data have been published about the frequency of antibodies to Hsp90 with the previous methodology using a complex Western blot system. We now describe an ELISA to measure autoantibodies to Hsp90 and Hsp70 in SLE patients, healthy controls and patients with a variety of autoimmune rheumatic diseases. IgG and IgM antibodies were elevated in 26 and 35% of SLE patients, respectively. These results show autoantibodies to Hsp90 (but not Hsp70) are elevated in a significant proportion of patients with SLE (P < 0.025) compared to healthy controls; and that those with raised antibody levels were more likely to have renal disease and a low C3 level (P < 0.02).

Arthritis, Rheumatoid↗
PubMed1994

Autoantibodies in systemic lupus erythematosus.

Various autoantibodies are found in systemic lupus erythematosus. Anti-double-stranded DNA antibodies are the most pathognomonic and among the most extensively studied. Genetic studies of these antibodies and their idiotypes suggest that high-affinity IgG anti-double-stranded DNA antibodies are produced by a process of somatic mutation and clonal expansion favoring sequences with accumulated positively charged amino acids in the complementarity-determining regions. The antigens that trigger this process are not known, but recent studies have suggested that a DNA-protein complex may be implicated. At the tissue level, these antibodies may react directly with membrane proteins or indirectly via complexes with DNA, histones, and heparan sulfate. Serologic studies have sought to establish links between clinical features and the presence of particular non-DNA-binding autoantibodies. Of particular interest have been antibodies to proteins with nucleic acid-binding potential, such as Sm, SS-A (Ro), and SS-B (La).

Antibodies, Anti-Idiotypic↗
PubMed1994

Beta 2 glycoprotein-I antigen is increased in primary hyperlipidaemia.

In order to determine whether elevated levels of beta 2 glycoprotein-I (beta 2GPI) are associated with increased plasma lipids, we measured plasma beta 2GPI antigen levels in 47 patients with primary hyperlipidaemia (20 severe hypercholesterolaemia, nine severe hypertriglyceridaemia, and 18 mixed hyperlipidaemia) and 34 normal healthy subjects. Mean beta 2GPI levels were significantly increased in each patient group (302.3, 272.9 and 299.1 mg/l, respectively) compared to controls (199.6 mg/l) (P < 0.01). Significant correlations were demonstrated between beta 2GPI levels and triglyceride and total cholesterol levels in the control group (r = 0.387, r = 0.559; P < 0.05), but were not observed in all patient groups. These results indicate that beta 2GPI is increased in hyperlipidaemia and that its distribution between plasma lipid fractions is perturbed. Plasma lipid levels should therefore be considered when interpreting results of beta 2GPI antigen assays.

Adult↗