Antibodies to vesicular stomatitis virus proteins in patients with systemic lupus erythematosus and in normal subjects

Exploring the Potential of Big Data Analytics in Urban Epidemiology Control: A Comprehensive Study Using CiteSpace

In recent years, there has been a growing amount of discussion on the use of big data to prevent and treat pandemics. The current research aimed to use CiteSpace (CS) visual analysis to uncover research and development trends, to help academics decide on future research and to create a framework for enterprises and organizations in order to plan for the growth of big data-based epidemic control. First, a total of 202 original papers were retrieved from Web of Science (WOS) using a complete list and analyzed using CS scientometric software. The CS parameters included the date range (from 2011 to 2022, a 1-year slice for co-authorship as well as for the co-accordance assessment), visualization (to show the fully integrated networks), specific selection criteria (the top 20 percent), node form (author, institution, region, reference cited, referred author, journal, and keywords), and pruning (pathfinder, slicing network). Lastly, the correlation of data was explored and the findings of the visualization analysis of big data pandemic control research were presented. According to the findings, "COVID-19 infection" was the hottest cluster with 31 references in 2020, while "Internet of things (IoT) platform and unified health algorithm" was the emerging research topic with 15 citations. "Influenza, internet, China, human mobility, and province" were the emerging keywords in the year 2021-2022 with strength of 1.61 to 1.2. The Chinese Academy of Sciences was the top institution, which collaborated with 15 other organizations. Qadri and Wilson were the top authors in this field. The Lancet journal accepted the most papers in this field, while the United States, China, and Europe accounted for the bulk of articles in this research. The research showed how big data may help us to better understand and control pandemics.

Cellular and humoral immunity to Ebola Zaire glycoprotein and viral vector proteins following immunization with recombinant vesicular stomatitis virus-based Ebola vaccine (rVSVΔG-ZEBOV-GP)

While effective at preventing Zaire ebolavirus (ZEBOV) disease, cellular immunity to ZEBOV and vector-directed immunity elicited by the recombinant vesicular stomatitis virus expressing ZEBOV glycoprotein (rVSVΔG-ZEBOV-GP) vaccine remain poorly understood. Sera and peripheral blood mononuclear cells were collected from 32 participants enrolled in a prospective multicenter study [ClinicalTrials.gov NCT02788227] before vaccination and up to six months post-vaccination. IgM and IgG antibodies, IgG-producing memory B cells (MBCs), and T cell reactivity to ZEBOV glycoprotein (ZEBOV-GP), vesicular stomatitis virus-Indiana strain (VSV-I) matrix (M) protein, and VSV-I nucleoprotein (NP) were measured using ELISA, ELISpot, and flow cytometry, respectively. 11/32 (34.4%) participants previously received a different investigational ZEBOV vaccine prior to enrollment and 21/32 (65.6%) participants were ZEBOV vaccine naïve. Both ZEBOV vaccine naïve and experienced participants had increased ZEBOV-GP IgG optical densities (ODs) post-rVSVΔG-ZEBOV-GP vaccination while only ZEBOV vaccine naïve participants had increased ZEBOV-GP IgM ODs. Transient IgM and IgG antibody responses to VSV-I M protein and NP were observed in a minority of participants. All participants had detectable ZEBOV-GP specific IgG-producing MBCs by 6 months post-vaccination while no changes were observed in the median IgG-producing MBCs to VSV-I proteins. T cell responses to ZEBOV-GP differed between ZEBOV vaccine experienced and ZEBOV vaccine naïve participants. T cell responses to both VSV-I M protein and VSV-I NP were observed, but were of a low magnitude. The rVSVΔG-ZEBOV-GP vaccine elicits robust humoral and memory B cell responses to ZEBOV glycoprotein in both ZEBOV vaccine naïve and experienced individuals and can generate vector-directed T cell immunity. Further research is needed to understand the significance of pre-existing vector and target antigen immunity on responses to booster doses of rVSVΔG-ZEBOV-GP and other rVSV-vectored vaccines.

Anti-Ro and Concomitant Anti-La Autoantibodies Strongly Associated With Anti-oxLDL or Anti-Phospholipid Antibody in Systemic Lupus Erythematosus

BACKGROUND

Premature atherosclerosis is observed in systemic lupus erythematosus (SLE). Oxidative modification of LDL is associated with atherosclerotic plaque formation.

OBJECTIVES

We hypothesized that anti-oxidized LDL (oxLDL) and anti-phospholipid (APL) in SLE sera would segregate with specific antibody subsets, and that anti-oxLDL antibodies will linger in circulation over an extended period.

PATIENTS AND METHODS

Sixty-seven SLE and control subjects and two SLE subjects with sera collected longitudinally for 13 years were tested for anti-oxLDL and IgG/IgM/IgA APL antibodies.

RESULTS

Anti-oxLDL ELISA values above 57.48 Activity Units (AcU) (means of normals + 3 standard deviations) and anti-IgG/IgM/IgA APL above 10 phospholipid units (PU) were considered positive. Average anti-oxLDL was 67.7 ± 50.5 AcU in SLE compared to 23.9 ± 11.19 AcU in normals (P = 0.018). Ten out of ten subjects with anti-Ro60/anti-La/anti-Ro52 antibodies had highly significant (P < 0.0001) anti-oxLDL (127.29 ± 45.67 AcU) and IgG APL (18.66 ± 7.4 PU) (P < 0.02). Subjects with anti-RNP were positive for anti-oxLDL (P < 0.002), but subjects with anti-Ro60/anti-Ro52 and subjects negative for extractable nuclear antigen (ENA) antibody were not positive for anti-oxLDL. Anti-oxLDL/anti-IgG APL remained significantly elevated in two patients studied longitudinally. Interestingly, one developed anti-oxLDL/anti-APL antibodies several years before anti-Ro60 development.

CONCLUSIONS

Presence of antibodies against Ro RNP and La, and RNP is highly associated with developing anti-oxLDL and APL antibodies in SLE. It will be clinically important to see if cardiovascular events occur in these SLE subsets having elevated anti-oxLDL and APL antibodies. Emergence of anti-oxLDL/IgG APL before anti-Ro60 over time in a patient indicates that these antibodies could not be cross-reactive in nature, at least in this particular patient.

The curiously suspicious: a role for Epstein-Barr virus in lupus

While the events initiating the development of autoantibodies in systemic lupus erythematosus (SLE) have not yet been convincingly established, newly developed tools for molecular investigation make such an undertaking increasingly practical. Applied to the earliest events in the sequence culminating in lupus autoimmunity, we present a critical potential role for Epstein-Barr virus (EBV) in the development and perhaps perpetuation of SLE. The expected properties for an environmental risk factor for SLE are found in this virus and the human host response against it. Existing data show the molecular progression to autoimmunity observed in SLE patient sera, the discovery of the first autoimmune epitopes in the Sm and Ro autoantigen systems, and the possible emergence of these autoantibodies from the heterologous antibodies against Epstein-Barr nuclear antigen-1 (EBNA-1). Further, existing data demonstrate association of SLE with EBV infection, even preceding the development of autoimmunity. Finally, the data are consistent with a proposed model of lupus pathogenesis that begins with antibodies to EBNA-1, predisposing to immune responses that develop crossreactive autoantibodies that culminate in the development of SLE autoimmunity.

Systemic Lupus Erythematosus: Recent Concepts in Genomics, Pathogenetic Mechanisms, and Therapies

Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disorder associated with multiple immunological abnormalities and a wide range of clinical manifestations. Recent progress in genetics has expanded the number of the genes associated with SLE to more than 20 in number and has contributed to improvement of understanding of the pathogenesis of the disease. This has enhanced the development of novel therapeutic targets and biomarkers for individualized and tailor-made clinical management of lupus patients. Despite this knowledge, however, it is a challenge to fully understand the genetic pathogenesis of the disease. The present paper describes the current concepts in the mechanisms, genomics, and pathogenesis of SLE and their implications for management of the disorder. The potential role of gene therapy, biological agents, intravenous immunoglobulin, anti-inflammatory cytokines, and cytokine inhibitors is discussed.

Toll-like receptor driven B cell activation in the induction of systemic autoimmunity

Studies over the past decade have demonstrated a key role for pattern recognition receptors in the activation of autoreactive B cells. Self reactive B cells that manage to escape negative selection often express relatively low affinity receptors for self antigens (ignorant B cells), and can only be activated by integrating a relatively weak BCR signal with signals from additional receptors. Members of the toll-like receptor (TLR) gene family, and especially the nucleic acid binding receptors TLR 7, 8 and 9, appear to play a key role in this regard and promote the production of autoantibodies reactive with DNA- or RNA-associated autoantigens. These autoantibodies are able to form immune complexes with soluble or cell-bound ligands, and these immune complexes can in turn activate a second round of proinflammatory cells that further contribute to the autoimmune disease process. Recent data have emerged showing a pathogenic role for TLR7, with an opposing, protective role for TLR9. Targeting these disregulated pathways offers a therapeutic opportunity to treat autoimmune diseases without crippling the entire immune system. Further understanding of the role of specific receptors, cell subsets, and inhibitory signals that govern these TLR-associated pathways will enable future therapeutics to be tailored to specific categories of autoimmune disease.

Antibody-mediated enhancement of the rate, magnitude, and responsiveness of vesicular stomatitis virus induced alpha interferon production

A majority of adults without evidence of exposure to vesicular stomatitis virus (VSV) have serum IgG antibodies that interact with pro-inflammatory TLR7 in the presence of VSV, and enhance several aspects of VSV-induced IFN-alpha production. Enhancing IgG antibody enables human PBMC to make IFN-alpha more rapidly and in higher titers in response to a broad range of VSV-concentrations that include those too low to independently stimulate IFN-alpha production. These antibody-mediated functions compensate for the inherent delay in virus-induced IFN-alpha production in vitro, and have the potential to improve the in vivo IFN-alpha response and effectively terminate infection before the occurrence of clinically apparent disease. The frequent presence of enhancing antibody in persons without predictable VSV exposure has implications for naturally occurring infections with this and other viruses, and for the use of viruses as vaccine vectors and oncolytic agents.

Pet dogs owned by lupus patients are at a higher risk of developing lupus

The aim of this study is to determine whether pet dogs owned by patients with systemic lupus erythematosus (SLE) are at a higher risk of developing SLE. Diagnosis of canine SLE was mainly based on the 11 diagnostic criteria for human SLE and two marked immunological features of canine SLE. Among 59 pet dogs owned by 37 SLE patients, 11 (18.64%) were ANA positive, and three (5.08%) had SLE. In contrast, of 187 pet dogs owned by non-SLE households, nine (4.81%) were ANA positive, and none (0%) had SLE. Among 650 outpatient dogs registered in the veterinary hospital, 34 (5.23%) were ANA positive, and six (0.92%) had SLE. Frequency of ANA and SLE among pet dogs owned by SLE patients was significantly higher than in pet dogs owned by non-SLE households (P = 0.001 for ANA; P = 0.013 for SLE) and in outpatient dogs (P < 0.001 for ANA; P = 0.032 for SLE). With respect to canine SLE development, the relative risk or risk ratio (R) of human SLE contact varied from 5.5 (compared with outpatient dogs) to near the infinite (compared with dogs owned by non-SLE households). The prevalence of canine SLE among pet dogs of SLE patients was therefore estimated to be 508 per 10 000 [95% confidence interval (95% CI), 0-1068]. In conclusion, pet dogs with human SLE contact were at a higher risk of developing SLE. Our results indicate that a common environmental factor or zoonotic agent may be involved in the development of human and canine SLE.

Lupus erythematosus induced by medications, ultraviolet radiation, and other exogenous agents: A review, with special focus on the development of subacute cutaneous lupus erythematosus in a genetically predisposed individual

Exogenous agents implicated in or suspected of precipitating subacute cutaneous lupus erythematosus (SCLE) and lupus erythematosus (LE) are reviewed. An illustrative case of environmentally induced SCLE is presented. A previously healthy 30-year male homozygous for the tumor necrosis factor-alpha (TNF-alpha) 308. A promoter allele developed SCLE after spending several hours removing fertilizer- and pesticide-containing hay from an agricultural barn in the springtime. The cutaneous eruption soon resolved, only to reappear 3 weeks later on the day the patient re-entered the barn. An environmental agent present in the barn, coupled with springtime ultraviolet light, likely triggered the disease in this immunogenetically susceptible individual.

Immunopathology and the gene therapy of lupus

Lupus is a chronic autoimmune inflammatory disease with complex clinical manifestations. In humans, lupus, also known as systemic lupus erythematosus (SLE), affects between 40 and 250 individuals, mostly females, in each 100 000 of the population. There are also a number of murine models of lupus widely used in studies of the genetics, immunopathology, and treatment of lupus. Human patients and murine models of lupus manifest a wide range of immunological abnormalities. The most pervasive of these are: (1) the ability to produce pathogenic autoantibodies; (2) lack of T- and B-lymphocyte regulation; and (3) defective clearance of autoantigens and immune complexes. This article briefly reviews immunological abnormalities and disease mechanisms characteristic of lupus autoimmunity and highlight recent studies on the use of gene therapy to target these abnormalities.

Immunization as a model for systemic lupus erythematosus

BACKGROUND

Immunization of laboratory animals is a new model system for systemic lupus erythematosus (SLE) and the autoimmunity of SLE.

OBJECTIVE

Review the published reports describing immunization as a model of SLE and describe the state of this research as well as future objectives as related to human illness.

METHODS

Medline search for relevant articles as well as review of cited bibliographies.

RESULTS

Either rabbits or mice can be immunized with proteins or oligopeptides that are lupus autoantigens with a resulting immune response not just to the immunogen but instead to a host of other self components that are also SLE-associated autoantigens. Several studies have noted clinical illness in these animals that resembles human SLE. In addition, injection of pristane (a component of mineral oil) also results in SLE-like autoimmunity, even though lupus autoantigens are not present. Pristane injected animals may also develop an SLE-like illness. There are reports of human SLE having its onset after immunization, but there have been no prospective studies.

CONCLUSIONS

Studies are needed to determine whether human SLE tends to begin soon after immunization. Meanwhile, continued study of animal models developed after immunization is needed in order to determine the relevance of this model to human disease.

RELEVANCE

SLE and/or SLE-like autoimmunity can be triggered after immunization of animals. This may be a model for an environmental trigger of human SLE.

Fine specificity of the autoimmune response to the Ro/SSA and La/SSB ribonucleoproteins

The fine specificity of the Ro and La proteins has been studied by several techniques. In general, there is agreement in a qualitative sense that autoantibodies bind multiple epitopes. For some specific antibody binding, different studies agree quantitatively, for instance, the binding of the carboxyl terminus of 60-kd Ro as described by 2 studies using different techniques and the presence of an epitope within the leucine zipper of 52-kd Ro. In addition, there is general agreement about the location of a prominent epitope at the RRM motif region of the La molecule. On the other hand, the many specific epitope regions of the molecules differ among these studies. These discrepancies are likely the result of using different techniques, sera, and peptide constructs as well as a result of inherent advantages and disadvantages in the individual approaches. Several theories concerning the origin of not only the antibodies, but also the diseases themselves, have been generated from studies of the fine specificity of antibody binding. These include a theory of a primordial foreign antigen for anti-Ro autoimmunity, molecular mimicry with regard to La and CCHB, as well as the association of anti-Ro with HLA. These remain unproven, but are of continuing interest. An explanation for the association of anti-60-kd Ro and anti-52-kd Ro in the sera of patients has sprung from evaluating antibody binding. Data demonstrating multiple epitopes are part of a large body of evidence that strongly suggests an antigen-driven immune response. This means that the autoantigens are directly implicated in initiating and sustaining autoimmunity in their associated diseases. A number of studies have investigated the possibility of differences in the immune response to these antigens in SS and SLE sera. While several differences have been reported, none have been reproduced in a second cohort of patients. Furthermore, none of the reported differences may be sufficiently robust for clinical purposes, such as distinguishing between SS with systemic features and mild SLE, although some might be promising. For instance, in at least 3 groups of SLE patients, no binding of residues spanning amino acids 21-41 of 60-kd Ro has been found. Meanwhile, 1 of those studies found that 41% of sera from patients with primary SS bound the 60-kd Ro peptide 21-41. Perhaps future studies will elaborate a clinical role of such a difference among SS and SLE patients. Study of the epitopes of these autoantigens has, in part, led to a new animal model of anti-Ro and anti-La. Non-autoimmune-prone animals are immunized with proteins or peptides that make up the Ro/La RNP. Such animals develop an autoimmune response to the entire particle, not just the immunogen. This response has been hypothesized to arise from autoreactive B cells. In another, older animal model of disease, the MRL-lpr/lpr mouse, B cells have recently been shown to be required for the generation of abnormal, autoreactive T cells. Thus, there are now powerful data indicating that B cells that produce autoantibodies are directly involved in the pathogenesis of disease above and beyond the formation of immune complexes. Given that the autoreactive B cell is potentially critical to the underlying pathogenesis of disease, then studying these cells will be crucial to further understanding the origin of diseases associated with Ro and La autoimmunity. Hopefully, an increased understanding will eventually lead to improved treatment of patients. Progress in the area of treatment will almost surely be incremental, and studies of the fine specificity of autoantibody binding will be a part of the body of basic knowledge contributing to ultimate advancement. In the future, the animal models will need to be examined with regard to immunology and immunochemistry as well as genetics. The development of these autoantibodies has not been studied extensively because upon presentation to medical care, virtually all patients have a full-

B-cell epitope spreading in autoimmunity

How the immune response matures from recognizing a single or a few structures of the antigen to many is an obviously important process. Models of B-cell epitope spreading have been developed in a variety of systems. For example, immunization of animals with PPPGMRPP, one of the earliest B-cell epitopes in the anti-Sm response found in human lupus, leads to antispliceosomal autoimmunity and features of lupus. The humoral immune response spreads from PPPGMRPP to other structures of the spliceosome in an apparently reproducible sequence. B-cell epitope spreading has provided the experimental basis from which a relationship between lupus and Epstein-Barr virus was suspected. An understanding of B-cell epitope spreading is likely to lead to important principles in basic immunology and to answers to human disease problems.

Rheumatoid hyperviscosity: analysis of a patient with intermediate complexes that block other autoantibodies and a review of the literature

OBJECTIVES

To report a patient who rheumatoid arthritis presented with hyperviscosity syndrome, analyze this patient's rheumatoid factor, and review the previously reported patients.

METHODS

Immunofluorescence for antinuclear antibodies, double immunodiffusion, enzyme-linked immunosorbent assay, and size exclusion chromatography were used before and after plasmapheresis to study the patient's rheumatoid hyperviscosity, and polyclonal gammopathy and references in identified papers was used to identify previously reported patients.

RESULTS

Similar to several previous patients, this patient's sera contained both IgG and IgM rheumatoid factor and abundant intermediate complexes. Other autoantibodies, either from the patient or from other patients, were masked by rheumatoid factor or intermediate complexes from the reported patients sera. Rheumatic hyperviscosity is seen uncommonly, being reported in only 18 patients with rheumatoid arthritis and nine with other rheumatic illnesses.

CONCLUSIONS

There are two mechanisms by which rheumatoid factor can lead to hyperviscosity, both of which require large amounts of rheumatoid factor. Rheumatoid hyperviscosity must be recognized because this life-threatening syndrome usually can be successfully treated with plasmapheresis acutely and immunosuppressives for long-term control.

Peripheral blood in Sjögren's syndrome does not contain increased levels of T lymphocytes reactive with the recombinant Ro/SS-A 52 kD and La/SS-B 48 kD autoantigens

Patients with Sjögren's syndrome (SS) frequently have anti-Ro/SS-A and anti-La/SS-B autoantibodies. The aim of this study was to investigate if these patients have peripheral blood lymphocytes (PBL) secreting IFN-gamma after short-term cultivation in the presence of Ro/SS-A and La/SS-B antigens. The frequency of PBL secreting IFN-gamma was examined in 12 SS patients and 11 healthy controls. The enzyme-linked immunospot (ELISPOT) assay was performed after 48 hours cultivation of PBL in the presence of recombinant Ro 52 kD protein or recombinant La 48 kD protein. The number of unstimulated IFN-gamma secreting cells in the SS patient group was not significantly different from that of the control group. Moreover, no increase in the number of IFN-gamma secreting cells after Ro/SS-A and La/SS-B stimulation was detected in the two groups. Thus, T cells reactive with the recombinant Ro 52 kD and La 48 kD proteins do not occur with any increased frequency in peripheral blood of SS patients.

Synovial fluid cells in systemic lupus erythematosus: light and electron microscopic studies

Joint fluid findings in systemic lupus erythematosus (SLE) have been described in only a few series and systematic electron microscopic study of the synovial fluid (SF) cells has not been reported. We describe the evaluation of 17 SF in patients with SLE with routine analysis and electron microscopy. Joint effusions had a wider range of leukocyte counts than often appreciated, with counts varying from 875 to 39,250 cells per mm3. LE inclusions were seen in eight fluids and have been shown to contain chromatin-like filaments by electron microscopy. There was little associated electron dense immunoglobulin-like material. Tubuloreticular structures (TRS) found in seven SF were mostly in mononuclear cells including some LE cells. The known association of TRS with alpha interferon and viral infections may have important implications for pathogenesis.

Human autoantibodies directed against the RNA recognition motif of La (SS-B) bind to a conformational epitope present on the intact La (SS-B)/Ro (SS-A) ribonucleoprotein particle

In systemic autoimmunity, the human B cell response to the La (SS-B) autoantigen is polyclonal and directed to both conserved and human-specific epitopes. This study has further characterized the B cell epitope(s) present within the conserved central region of the La protein, LaC (amino acids 111-242) containing the RNA recognition motif (RRM, aa 111-187). Ten overlapping and non-overlapping protein fragments spanning LaC were expressed in bacteria as NH2-terminal fusions with glutathione-S-transferase. The fusion proteins were tested by ELISA for reactivity with a panel of human anti-La sera in order to define the nature of the epitopes. Ninety-two percent of patient sera containing anti-La antibodies reacted with the region of La containing the RRM. Fine mapping of this reactivity using deletion mutants indicated that the deletion of 19 amino acids from either the NH2-terminal or COOH-terminal region of the RRM was associated with loss of antibody reactivity, suggesting that the immunodominant epitope expressed in this region is discontinuous. Autoantibodies affinity-purified from the La RRM fragment to remove other specificities immunoprecipitated newly synthesized native La (SS-B)/Ro (SS-A) complexes, providing additional evidence that autoantibodies were recognizing a conformational epitope. The findings indicate that the human autoantibody response to La involves recognition of a conformational determinant involving the conserved RRM region without necessarily interfering with the RNA-dependent association of the La/Ro ribonucleoprotein.

Human anti-Ro autoantibodies bind peptides accessible to the surface of the native Ro autoantigen

The relationship between fine specificity of linear epitopes and conformational determinants has been explored in a naturally arising human autoimmune response. In particular, the hypothesis tested is that the linear epitopes of the human Ro autoantigen are components of its conformational epitopes. Twenty groups among the 531 overlapping octapeptides 60 kDa Ro are variably bound by anti-Ro precipitin positive lupus sera whose reactivity was easily distinguished from sera of normal controls and of anti-Ro precipitin negative lupus patients. The specific activities of anti-peptide antibodies and of anti-native Ro autoantibodies are similarly increased after affinity enrichment using native human Ro as ligand. Moreover, affinity-enriched anti-native Ro autoantibodies bind virtually the same 20 groups of epitopes recognized by whole anti-Ro positive sera. Two peptides (residues 274-290 and 480-494) from the defined 60 kDa Ro octapeptide epitopes have been prepared and used as ligands for affinity purification of peptide specific autoantibodies. The binding of both whole IgG and affinity-enriched peptide specific autoantibodies is inhibited by native Ro autoantigen. Thus, none of the available data can be construed to support the existence of cryptic linear epitopes in this system. Indeed, the data are only consistent with the conclusion that all of the anti-Ro octapeptide autoantibodies are part of the population of anti-native Ro autoantibodies in this naturally arising autoimmune response.

Immunogenetics of epitopes of the carboxyl terminus of the human 60-kD Ro autoantigen

Systemic lupus erythematosus is associated with the presence of autoantibodies which bind several ribonucleoproteins, including Ro (or SS-A). We have explored the relationship of the HLA-DQ and T cell receptor alleles in patients producing autoantibodies binding the 13-kD carboxyl terminus fragment of the 60-kD Ro and with autoantibodies binding a peptide epitope within this fragment (amino acid residues 480-494). Antibodies binding the 13-kD fragment are more likely to be found in the sera of patients with particular DQA1 and DQB1 alleles, while antibodies binding the epitope at 480-494 are found almost exclusively in the sera of patients with a Bg/II 9.8-kb polymorphism of the T cell receptor beta gene. Meanwhile, in these same patient sera the level of autoantibodies binding the complete 60-kD Ro particle is associated with a distinct pattern of alleles at these same immunoregulatory loci. These data demonstrate that component parts of autoantibody responses may be under genetic control which can be distinguished from the HLA associations characteristic of the response to the intact, complete autoantigen.

Antibodies to EYRKK vesicular stomatitis virus-related peptide account only for a minority of anti-Ro60kD antibodies

Previous studies demonstrated a possible antigenic relation between the carboxyl terminal portion of anti-Ro60kD autoantigen and a nucleocapsid protein (N) of vesicular stomatitis virus (VSV). In order to investigate whether anti-Ro60kD autoantibodies react with the VSV homologous region of the Ro60kD protein we synthesized, according to Merrifield's method, the EYRKKMDI octapeptide (8p) sharing a common sequence with the N protein of VSV. Sera from 61 patients with autoimmune rheumatic diseases (34 systemic lupus erythematosus (SLE), 21 Sjörgren's syndrome (SS) and six rheumatoid arthritis (RA)) as well as 59 from normal blood donors were tested for the presence of anti-Ro60kD autoantibodies by ELISA and immunoblot (IB) and anti-8p antibodies by ELISA. Antibodies to 8p were found in 9/31 of anti-Ro60kD IB-positive sera, 5/30 of anti-Ro60kD-negative sera and 2/59 of normal control sera. The concordance between the anti-8p ELISA and the anti-Ro60kD IB was very poor (chi 2 = 0.71, P = 0.4) in contrast to the anti-Ro60kD ELISA and the anti-Ro IB (chi 2 = 27.6, P = 10(-7)). Subsequent affinity purification of the anti-8p antibodies from a strong positive anti-8p and anti-Ro60kD SLE serum yielded 95% depletion of the anti-8p activity and 37% reduction of the anti-Ro60kD activity. Inhibition assays with the affinity-purified anti-8p antibodies demonstrated that the octapeptide gave 94.5% inhibition of the anti-Ro60kD activity, while Ro60kD protein led to 42.3% inhibition of the anti-8p. Preincubation of the serum with the octapeptide produced 4% inhibition of anti-Ro60kD ELISA. These results indicate that the anti-8p antibodies account only for a minority of the anti-Ro60kD autoantibodies.