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Biomedical subjects

D A Isenberg

Publications and source records attributed to D A Isenberg.

At least 199 records · Page 11Linked to original sources
PubMed1996

Sequences of monoclonal antiphospholipid antibodies: variations on an anti-DNA antibody theme.

Antiphospholipid antibodies (aPL) are recognized increasingly as a probable cause of clinical features such as thrombosis and recurrent miscarriages, particularly in a subset of patients with systemic lupus erythematosus (SLE) and those with the antiphospholipid antibody syndrome (APS). A powerful method of studying the origin of these antibodies and delineating their binding sites is to sequence monoclonal aPL. The few reports of mouse aPL sequences suggest that gene families J558 and Vk23 may be used preferentially but without extensive mutation of complementarity determining regions (CDR). Polyreactive human aPL, which bind DNA as well as phospholipids, generally use germline genes with few mutations. Specific immunoglobulin (Ig) M aPL also tend to use relatively unmutated genes but often have high concentrations of positive residues in CDR, which may enhance binding to anionic phospholipids. IgG aPL show many more antigen-selected mutations, particularly in heavy chain CDR. This difference between isotypes is similar to that seen in anti-DNA antibodies, but the role of positively charged residues in aPL is less evident, and additional motifs are likely to be important in antigen binding.

Animals↗
PubMed1996

Neuroendocrine changes in systemic lupus erythematosus and Sjögren's syndrome.

It has become clear that the neuroendocrine and immune systems are closely linked and interdependent. The exact mechanisms of this interaction are only beginning to be unravelled. The complexity of these connections may partly explain why the aetiopathogenesis of autoimmune diseases remains obscure and why genetic, hormonal, microbial, environmental, as well as a host of other factors, have all been put forward as explanations. What has become clear is that a number of neuroendocrine and hormonal factors have important immunomodulatory roles in health and disease.

Animals↗
PubMed1996

Fc gamma RIIa polymorphism in systemic lupus erythematosus (SLE): no association with disease.

An allotypic variant of Fc gamma RIIa, Fc gamma RIIa-HR (Fc gamma RIIa-R131), has been shown in vitro to reduce the capacity of phagocytic cells to bind and internalize IgG-containing immune complexes. Our aim was to determine whether this allotypic variant was associated with susceptibility to SLE and the development of lupus nephritis, as previous studies have suggested. Fc gamma RIIA genotype analysis was performed by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) in 215 Caucasoid, 70 Afro-Caribbean, and 46 Chinese patients with SLE, and in 259,77 and 49 ethnically matched controls, respectively. Distribution of Fc gamma RIIa genotypes between the patients and ethnically matched controls was not significantly different in the three populations studied. No association between the Fc gamma RIIa-HR allotype and nephritis was found. Our results suggest that the Fc gamma RIIa-HR allotype is not a major factor predisposing to the development of SLE, or to lupus nephritis.

Base Sequence↗
PubMed1996

Correlation between expression of antibodies to histone H2B and clinical activity in HIV-infected individuals.

Levels of autoantibodies specific for the histone, H2B, were measured in individuals with HIV infection. In comparison with normal (uninfected) controls, infected patients, particularly those with symptomatic disease, had significantly elevated titres of anti-H2B antibodies. Longitudinal studies confirmed that levels of these antibodies were highest in patients with lymphadenopathy and declined with the development of AIDS. In preliminary experiments designed to determine the biological significance of the anti-histone antibodies, H2B was shown to be immunologically cross-reactive with an 18-kD antigen on the surface of HIV-infected or mitogen-activated CD4+ cells. Protein sequencing of the 18-kD antigen has since shown complete homology with histone H2B. Because the titres of H2B autoantibodies were found to parallel the numbers of circulating CD4 cells, it is possible that these antibodies are involved in the destruction of the helper/inducer T lymphocyte population.

Autoantibodies↗
PubMed1996

An analysis of apoptosis in lymphoid organs and lupus disease in murine systemic lupus erythematosus (SLE).

Apoptosis is a programmed cell death process that helps to regulate both T cell and B cell development. In this study, we have investigated the levels of apoptotic death in cells of the thymuses and spleens (white matter) of autoimmune MRL-lpr/lpr mice with progressive lymphadenopathy and SLE disease activity; we also examined the renal pathology in these animals. Fas is a cell surface receptor, which when activated initiates the sequence of events that lead to apoptosis. In MRL-lpr/lpr mice Fas is defective, so the competency for apoptosis may be reduced. In young animals of advancing age the thymuses enlarged until in 5-month-old females the average weight was three times that at 1 month, and spleen and kidney weights also increased in size disproportionately. At light microscope level apoptotic cells in tissue sections were counted using both routine eosin and haematoxylin staining (to identify them by their morphology) and in situ end-labelling of cells with DNA strand breaks; their presence was further confirmed by electron microscopy. As the mice aged, the numbers of apoptotic cells in thymic cortex, thymic medulla and spleen white pulp areas reduced significantly (P < 0.01-0.001), whereas in BALB/c normal controls they increased significantly (P < 0.05). These changes were coincident with the development of severe lupus, whose activity was assessed by measuring serum anti-ssDNA and anti-dsDNA antibody titres and urinary protein (albumin) level which were elevated significantly by 5 months of age (P < 0.001 for both ssDNA and dsDNA and P < 0.01 for urine albumin) compared with their younger counterparts. Thus, lymphoid organ enlargement, decrease in apoptotic indices, elevated serum anti-ssDNA and anti-dsDNA antibody levels, and impaired renal function coincided with the onset and severity of lupus disease in lpr mice. It seems likely that there is a causal relationship between defective deletion of autoreactive lymphoid cells, imperfect Fas-mediated apoptosis and development of murine SLE.

Animals↗
PubMed1996

Analysis of immunoglobulin variable region genes of a human IgM anti-myeloperoxidase antibody derived from a patient with vasculitis.

Circulating antibodies to myeloperoxidase (MPO) are associated primarily with pauci-immune glomerulonephritis and systemic vasculitis. Anti-MPO antibodies belong to a group of autoantibodies, anti-neutrophil cytoplasmic antibodies, that may play a pathogenic role in vasculitis. We have generated a human monoclonal anti-MPO antibody (E3-MPO) using peripheral blood lymphocytes from a patient with microscopic polyarteritis. Variable region gene analysis of E3-MPO showed that the VH region had 90% homology with the germ line gene VH4-21. E3-MPO was also shown to carry the 9G4 idiotope, which so far has been associated only with human antibodies that utilize the VH4-21 gene. The 9G4 idiotope was also expressed on anti-MPO antibodies in sera from the donor patient and from 4/7 additional patients with active, untreated vasculitis. The nucleotide sequences of both the variable heavy and light chains of E3-MPO showed evidence of an antigen-driven response.

Adult↗
PubMed1996

Agalactosyl IgG and beta-1,4-galactosyltransferase gene expression in rheumatoid arthritis patients and in the arthritis-prone MRL lpr/lpr mouse.

Reduced galactosylation of immunoglobulin G (IgG) is well documented in rheumatoid arthritis (RA), but the reason for this defect is still unknown. There is some evidence supporting a defect in the biosynthetic pathway, and a reduction in the level of beta-1,4-galactosyltransferase (beta-1,4-GalTase) enzyme activity. Since glycosyltransferases are, in general, regulated at the level of transcription, we have measured the level of beta-1,4-GalTase gene expression in B cells from patients with RA and normal control individuals. We found no significant difference in mRNA levels for the transferase in these two groups (P > 0.7). MRL/Mp-lpr/lpr (MRL-lpr) mice develop a spontaneous arthritis with increased levels of agalactosyl IgG (G0). In spite of a significant reduction in the level of beta-1,4-GalTase mRNA in total spleen lymphocytes from MRL-lpr mice compared with the congenic MRL/Mp-(+/+) (MRL-(+/+) mice and with CBA/Ca mice, we found comparable levels of the beta-1,4-GalTase mRNA in purified B cells from both spleen and lymph nodes of the three strains. Amongst the lymphoid compartments examined, the spleen and peripheral blood were found to be the major contributors of G0 in MRL-lpr mice. These data indicate that in neither human RA, nor in an animal model of this disease, is reduced IgG galactosylation caused by impaired expression of the beta-1,4-GalTase gene in B lymphocytes. Furthermore, splenic B cells, which have normal levels of beta-1,4-GalTase mRNA, appear to be a major source of G0 in MRL-lpr mice.

Animals↗
PubMed1996

Ultraviolet irradiation in systemic lupus erythematosus: friend or foe?

The long established notion that UV irradiation is always harmful to patients with systemic lupus erythematosus has been challenged by some recent reports of benefit using a form of phototherapy with UV-A1. In the review we discuss the different types of UV radiation, the links between certain forms of such radiation and clinical manifestations and consider the mechanisms involved.

Humans↗
PubMed1996

Rheumatic disease patients, prone to Sjögren's syndrome and/or lymphoma, mount an antibody response to BHRF1, the Epstein-Barr viral homologue of BCL-2.

The IgG response to Epstein-Barr virus (EBV) early antigens [BHRF1 (p 17.1), the viral homologue of bcl-2, and BMRF1 (p50.10), a DNA binding protein] was measured in patients with rheumatic disease to see whether there was any association with lymphoma. Patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), rheumatic disease patients with lymphoma, patients with lymphoma who did not have a rheumatic disease and normal individuals were tested for the presence of anti-EA peptide antibodies by ELISA. Whereas antibodies to early EBV peptides were detected only in one normal individual, patients with rheumatic diseases, especially those with either SS and/or lymphoma, had a much higher frequency of antibody detection. Antibodies to BMRF1 p50.10 were found in 7-50% of patients, and to BHRF1 p17.1 in 4-27%, depending on the group studied. Patients with lymphoma lacking a rheumatic disease had a 2-fold lower frequency of anti-BHRF1 antibodies, compared to the lymphoma plus rheumatic disease group. The increased immune response to the EBV EA proteins in the rheumatic diseases probably reflects the presence of reactivated virus, and the BHRF1 protein (the viral homologue to bcl-2) could, via inhibiting apoptosis, contribute to the lymphoproliferative nature of these diseases.

Adult↗
PubMed1996

SLICC/ACR Damage Index is valid, and renal and pulmonary organ scores are predictors of severe outcome in patients with systemic lupus erythematosus.

We investigated the Systemic Lupus International Collaborative Clinics/American College of Rheumatology (SLICC/ACR) Damage Index as a predictor of severe outcome and an indicator of morbidity in different ethnic groups, and in regard to its validity. We retrospectively studied disease course within 10 yr of diagnosis in an inception cohort of 80 patients with systemic lupus erythematosus (SLE). The mean renal damage score (DS) at 1 yr after diagnosis was a significant predictor of endstage renal failure and the mean pulmonary DS at 1 yr significantly predicted death within 10 yr of diagnosis. Compared to Caucasians, Afro-Caribbeans and Asians had significantly higher mean total DS at 5 and 10 yr, and higher mean renal DS at 10 yr. At 5 yr, the mean renal DS in Afro-Caribbeans and the mean neuropsychiatric DS in Asians were significantly higher than in Caucasians. The rate of endstage renal failure in Caucasians was significantly lower than in the other ethnic groups. Our results confirm the validity of the SLICC/ACR Damage Index.

Adult↗
PubMed1996

T-lymphocyte immunophenotyping in polymyositis and dermatomyositis.

The objective was to elucidate the immunological abnormalities underlying polymyositis (PM) and dermatomyositis (DM). The phenotype of peripheral blood mononuclear cell (PBMNC) subsets and cell surface expression of activation (CD25 and HLA-DR) and adhesion (LFA-1) molecules was studied in 12 patients with PM and in 10 patients with DM. PBMNC subsets and expression of T-cell activation molecules were evaluated by cytofluorography. Double immunofluorescence and indirect immunoperoxidase techniques were applied to muscle biopsies to define T-cell phenotype and LFA-1/ICAM-1 expression. In PM, the absolute number of circulating cytotoxic (CD8+CD28+) T cells was selectively reduced. T cells showed increased expression of activation molecules, CD25 and HLA-DR, and increased adhesion capacity as the absolute numbers of CD3+CD25+, CD8+HLA-DR+, CD3+LFA-1+('bright') and CD8+ CD8+LFA-1+('bright') cells were higher than in healthy donors and DM patients. In PM muscle biopsies, T cells were mainly CD3+CD8+ and LFA-1+; additionally, endothelial cells and myofibres surrounded by T cells showed positive staining for ICAM-1. In DM, there was a general lymphopenia that led to a decreased absolute number of all T-lymphocyte subsets. It is proposed that in PM, in contrast to DM, LFA-1/ICAM-1 interactions enable activated CD8+ T cells to migrate selectively into the inflamed muscle and to adhere to myofibres, leading to tissue injury.

Adult↗
PubMed1996

Further validation of the BILAG disease activity index in patients with systemic lupus erythematosus.

OBJECTIVE: To examine the association among the BILAG disease activity index components and their relations with global assessments, health status, and laboratory tests with regard to the validity of the BILAG index. METHODS: A cross sectional study of consecutive patients with systemic lupus erythematosus (SLE) attending a specialist lupus outpatient clinic between July 1994 and February 1995. The internal consistency of the British Isles Lupus Assessment Group (BILAG) index-a disease activity assessment system for SLE patients, based on the principle of the physician's intention to treat-was examined using Cronbach's coefficient alpha. The association of the components of the BILAG index with health status as measured with the MOS Short Form 20 (SF-20), with patients' and doctors' global assessments of patient wellbeing and with laboratory tests was analysed with Spearman rank correlations. RESULTS: 133 female and eight male patients, age 20.1 to 88.7 years (mean 41.1, SD 12.5), were included. With few exceptions, the components of the BILAG index which reflect disease activity in different organ systems were not associated with each other. With the exception of the mucocutaneous component, we found a significant relation between all components of BILAG and global assessment of patient wellbeing, health status, erythrocyte sedimentation rate, or serum C3 level. CONCLUSIONS: The study confirms the validity of all but the mucocutaneous component of the BILAG index. However, disease activity in different organ systems in SLE does not follow a common pattern. Thus the individual BILAG components should be used rather than the total BILAG score as a primary endpoint in clinical and epidemiological studies. To capture the total effect of SLE on an individual measures of disease activity, damage, and health status are all needed.

Adult↗
PubMed1996

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.

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.

Adolescent↗
PubMed1996

beta 2 glycoprotein-I inhibits factor XII activation on triglyceride rich lipoproteins: the effect of antibodies from plasma of patients with antiphospholipid syndrome.

It is now well recognised that antiphospholipid antibodies are associated with thrombosis and recurrent fetal loss. Some antiphospholipid antibodies (aPAs) have been shown to require a cofactor, beta 2 glycoprotein-I (beta 2 GPI), for binding to phospholipids, and recently beta 2 GPI has been identified as the antigenic target for some aPAs. beta 2 GPI possesses in vitro anticoagulant properties and modulation of beta 2 GPI function may therefore result in altered haemostatic regulation. In the present study, the influence of plasma derived aPAs and beta 2 GPI on factor XII activation on the surface of very low density lipoprotein (VLDL) was investigated. Factor XIIa generation was dependent on lipoprotein lipase treatment of VLDL and beta 2 GPI inhibited the factor XIIa generation in a concentration dependent manner. No consistent effects on factor XIIa generation were demonstrated with the IgG fractions from patients with aPAs. Inhibition of the beta 2 GPI activity was demonstrated by some antibodies, and study with cardiolipin affinity purified antibody indicated that antibody concentration is critical. These results suggest that perturbation of beta 2 GPI function may contribute to the pathogenic mechanism for thrombosis in some patients with aPAs.

Adult↗
PubMed1995

Fetal calf serum in growth medium obscures the detection of early anticardiolipin antibody secreting clones.

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.

Animals↗