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1.  Multiple Autoantibodies Display Association with Lymphopenia, Proteinuria, and Cellular Casts in a Large, Ethnically Diverse SLE Patient Cohort 
Autoimmune Diseases  2012;2012:819634.
Purpose. This study evaluates high-throughput autoantibody screening and determines associated systemic lupus erythematosus (SLE) clinical features in a large lupus cohort. Methods. Clinical and demographic information, along with serum samples, were obtained from each SLE study participant after appropriate informed consent. Serum samples were screened for 10 distinct SLE autoantibody specificities and examined for association with SLE ACR criteria and subcriteria using conditional logistic regression analysis. Results. In European-American SLE patients, autoantibodies against 52 kD Ro and RNP 68 are independently enriched in patients with lymphopenia, anti-La, and anti-ribosomal P are increased in patients with malar rash, and anti-dsDNA and anti-Sm are enriched in patients with proteinuria. In African-American SLE patients, cellular casts associate with autoantibodies against dsDNA, Sm, and Sm/nRNP. Conclusion. Using a high-throughput, bead-based method of autoantibody detection, anti-dsDNA is significantly enriched in patienets with SLE ACR renal criteria as has been previously described. However, lymphopenia is associated with several distinct autoantibody specificities. These findings offer meaningful information to allow clinicians and clinical investigators to understand which autoantibodies correlate with select SLE clinical manifestations across common racial groups using this novel methodology which is expanding in clinical use.
PMCID: PMC3439936  PMID: 22988489
2.  Autoantibodies predate the onset of systemic lupus erythematosus in northern Sweden 
Autoantibodies have a central role in systemic lupus erythematosus (SLE). The presence of autoantibodies preceding disease onset by years has been reported both in patients with SLE and in those with rheumatoid arthritis, suggesting a gradual development of these diseases. Therefore, we sought to identify autoantibodies in a northern European population predating the onset of symptoms of SLE and their relationship to presenting symptoms.
The register of patients fulfilling the American College of Rheumatology criteria for SLE and with a given date of the onset of symptoms was coanalysed with the register of the Medical Biobank, Umeå, Sweden. Thirty-eight patients were identified as having donated blood samples prior to symptom onset. A nested case-control study (1:4) was performed with 152 age- and sex-matched controls identified from within the Medical Biobank register (Umeå, Sweden). Antibodies against anti-Sjögren's syndrome antigen A (Ro/SSA; 52 and 60 kDa), anti-Sjögren's syndrome antigen B, anti-Smith antibody, ribonucleoprotein, scleroderma, anti-histidyl-tRNA synthetase antibody, double-stranded DNA (dsDNA), centromere protein B and histones were analysed using the AtheNA Multi-Lyte ANA II Plus Test System on a Bio-Plex Array Reader (Luminex200). Antinuclear antibodies test II (ANA II) results were analysed using indirect immunofluorescence on human epidermal 2 cells at a sample dilution of 1:100.
Autoantibodies against nuclear antigens were detected a mean (±SD) of 5.6 ± 4.7 years before the onset of symptoms and 8.7 ± 5.6 years before diagnosis in 63% of the individuals who subsequently developed SLE. The sensitivity (45.7%) was highest for ANA II, with a specificity of 95%, followed by anti-dsDNA and anti-Ro/SSA antibodies, both with sensitivities of 20.0% at specificities of 98.7% and 97.4%, respectively. The odds ratios (ORs) for predicting disease were 18.13 for anti-dsDNA (95% confidence interval (95% CI), 3.58 to 91.84) and 11.5 (95% CI, 4.54 to 28.87) for ANA. Anti-Ro/SSA antibodies appeared first at a mean of 6.6 ± 2.5 years prior to symptom onset. The mean number of autoantibodies in prediseased individuals was 1.4, and after disease onset it was 3.1 (P < 0.0005). The time predating disease was shorter and the number of autoantibodies was greater in those individuals with serositis as a presenting symptom in comparison to those with arthritis and skin manifestations as the presenting symptoms.
Autoantibodies against nuclear antigens were detected in individuals who developed SLE several years before the onset of symptoms and diagnosis. The most sensitive autoantibodies were ANA, Ro/SSA and dsDNA, with the highest predictive OR being for anti-dsDNA antibodies. The first autoantibodies detected were anti-Ro/SSA.
PMCID: PMC3241374  PMID: 21342502
3.  60 kD Ro and nRNP A Frequently Initiate Human Lupus Autoimmunity 
PLoS ONE  2010;5(3):e9599.
Systemic lupus erythematosus (SLE) is a clinically heterogeneous, humoral autoimmune disorder. The unifying feature among SLE patients is the production of large quantities of autoantibodies. Serum samples from 129 patients collected before the onset of SLE and while in the United States military were evaluated for early pre-clinical serologic events. The first available positive serum sample frequently already contained multiple autoantibody specificities (65%). However, in 34 SLE patients the earliest pre-clinical serum sample positive for any detectable common autoantibody bound only a single autoantigen, most commonly 60 kD Ro (29%), nRNP A (24%), anti-phospholipids (18%) or rheumatoid factor (15%). We identified several recurrent patterns of autoantibody onset using these pre-diagnostic samples. In the serum samples available, anti-nRNP A appeared before or simultaneously with anti-nRNP 70 K in 96% of the patients who had both autoantibodies at diagnosis. Anti-60 kD Ro antibodies appeared before or simultaneously with anti-La (98%) or anti-52 kD Ro (95%). The autoantibody response in SLE patients begins simply, often binding a single specific autoantigen years before disease onset, followed by epitope spreading to additional autoantigenic specificities that are accrued in recurring patterns.
PMCID: PMC2835743  PMID: 20224770
4.  The clinical relevance of antibodies to ribosomal-P common epitope in two targeted systemic lupus erythematosus populations: a large cohort of consecutive patients and patients with active central nervous system disease 
Annals of the Rheumatic Diseases  2000;59(2):99-104.
OBJECTIVES—To develop an enzyme linked immunosorbent assay (ELISA) using as substrate a synthetic 22-aminoacid peptide, corresponding to the ribosomal P0, P1 and P2 common epitope. To study the specificity and sensitivity of the method and evaluate the frequency and clinical associations of anti-P antibodies in two groups of systemic lupus erythematosus (SLE) patients: (a) unselected SLE patients and (b) SLE patients with central nervous system (CNS) involvement.
PATIENTS AND METHODS—The C-terminal 22 aminoacid peptide of the ribosomal P proteins (Lys-Lys-Glu-Glu-Lys-Lys-Glu-Glu-Lys-Ser-Glu-Glu-Glu-Asp-Glu-Asp-Met-Gly-Phe-Gly-Leu-Phe-Asp) was synthesised according to Merrifield's solid phase procedure. Purification of the peptide was performed by preparative high performance liquid chromatography and confirmed by amino acid analysis. Using this peptide, in a concentration 5 µg/ml, an ELISA was developed. The presence of anti-P antibodies was evaluated by western blot using purified ribosomal proteins from rat liver. Sera from 178 consecutive patients with SLE and 28 patients with SLE and CNS manifestations were tested. Sera from 58 patients with rheumatoid arthritis and 57 patients with primary Sjögren's syndrome were used as controls. The cut off point of the assay was defined using 124 normal sera.
RESULTS—The specificity of the assay was evaluated by homologous inhibition. Pretreatment of positive sera with soluble 22mer peptide of the ribosomal P proteins resulted in 88% inhibition. The concordance between the peptide assay and western blot was found to be 83%. Thirty three of 178 (18.6%) of the unselected SLE patients had antibodies to P-protein common epitope. Their presence was associated with more active disease (European Consensus Lupus Activity Measurement, ECLAM scoring system) (p<0.001), higher levels of anti-ds DNA antibodies (p<0.05) and lower levels of the C4 component of complement (p<0.01). Eleven of 28 (39.3%) patients with SLE and active CNS involvement had antibodies to P-protein. The overall prevalence of anti-P antibodies in active CNS disease patients was statistically significantly higher, as compared with unselected SLE patients (χ2=6.04, p<0.05). These antibodies were found in a high proportion of patients without anticardiolipin antibodies (52.4%) and they were associated with diffuse CNS involvement (psychiatric disorders (71%) and epilepsy (75%)).
 CONCLUSIONS—A synthetic analogue of the common epitope of ribosomal P-proteins can be use as an antigen for the detection of anti-P antibodies. These antibodies are associated with active SLE and CNS involvement particularly in patients without anticardiolipin antibodies.

PMCID: PMC1753066  PMID: 10666163
5.  Association of cerebrospinal fluid anti-ribosomal P protein antibodies with diffuse psychiatric/neuropsychological syndromes in systemic lupus erythematosus 
We explored the relationship of antibodies to the whole ribosomal P proteins (P0, P1, and P2) in cerebrospinal fluid (CSF) with diffuse psychiatric/neuropsychological syndromes in systemic lupus erythematosus (SLE). CSF samples were obtained from 71 SLE patients (52 patients with diffuse psychiatric/neuropsychological syndromes [diffuse NP-SLE] and 19 patients with neurological syndromes or peripheral neuropathy [focal NP-SLE]) as well as from 24 patients with non-inflammatory neurological disease. Immunoglobulin G (IgG) antibodies to the C-terminal 22-amino acid ribosomal P synthetic peptide (anti-PC22) and those to purified bovine ribosomal P proteins (P0, P1, and P2) (anti-whole P) were determined by enzyme-linked immunosorbent assay; affinity-purified IgG anti-PC22 were used as the standard. The concentrations of antibodies to epitopes other than the C-terminal 22 amino acids of ribosomal P proteins were calculated by subtracting anti-PC22 from anti-whole P (anti-PEX.C22). CSF anti-whole P levels were significantly elevated in diffuse NP-SLE compared with focal NP-SLE or control patients. By contrast, there were no significant differences in CSF anti-PC22 levels among the three groups. Of note, CSF anti-PEX.C22 levels were significantly elevated in diffuse NP-SLE compared with the other two groups. CSF anti-PEX.C22 levels were not significantly correlated with CSF anti-PC22 levels, but with CSF antibodies against the recombinant ribosomal P0 protein lacking the C-terminal 22 amino acids (C22-depleted rP0). Moreover, levels of CSF anti-PEX.C22 or CSF anti-C22-depleted rP0, but not CSF anti-PC22, were significantly correlated with CSF anti-neuronal cell antibodies (anti-N). These results indicate that CSF IgG antibodies to the epitopes other than the C-terminal 22 amino acids of ribosomal P proteins, which might contain one of the major targets of CSF anti-N, are associated with the development of diffuse NP-SLE.
PMCID: PMC2206358  PMID: 17472755
6.  Fragment of tegument protein pp65 of human cytomegalovirus induces autoantibodies in BALB/c mice 
Arthritis Research & Therapy  2011;13(5):R162.
Human cytomegalovirus (HCMV) infection has been implicated in the development of autoimmunity, including systemic lupus erythematosus (SLE). Previously we reported that HCMV phosphoprotein 65 (pp65) could induce early onset of autoantibody and glomerulonephritis on lupus-prone NZB/W mice. This study further examined whether the B cell epitope(s) in pp65 is able to drive the development of autoantibody.
Sera from SLE patients or HCMVpp65-immunized mice were analyzed for anti-nuclear antibody by immunoblotting, enzyme-linked immunosorbent assay (ELISA), immunofluorescent stain and Crithidia luciliae stain. The deposition of immunoglobulin to the kidney was also examined by immunofluorescent stain. The interactions between pp65 sub-fragment to cellular proteins were revealed by yeast two-hybrid analyses.
Our results showed that most SLE patients possessed antibodies to the C-terminal half of the HCMVpp65 antigen. Of these positive sera, 73% were also positive to the pp65336-439 sub-fragment. The immunization of pp65336-439 induced formation of multiple anti-nuclear antibodies, including anti-chromatin, anti-centriole, anti-mitotic spindle type I/II (MSA I/II) and a significant elevation of anti-double-stranded DNA (anti-dsDNA) antibodies on BALB/c mice. Yeast two-hybrid analyses revealed the binding of pp65336-439 sub-fragment to cellular proteins. Immunoglobulin deposition on glomeruli was also detected on pp65336-439-immunized mice.
Our data suggested that HCMVpp65336-439 sub-fragment may induce cross-reactive antibodies to several nuclear antigens, which could contribute to the development of autoimmunity in genetic-suspected individuals.
PMCID: PMC3308095  PMID: 21989080
7.  Influenza vaccination can induce new onset anticardiolipins but not β2-glycoprotein-I antibodies among patients with systemic lupus erythematosus 
Lupus  2012;21(2):168-174.
Antiphospholipid syndrome is characterized by autoantibodies against cardiolipins (aCL), lupus anticoagulant, and independent β2-glycoprotein (β2GPI). Controversy exists as to whether vaccination triggers the development of anti-phospholipid antibodies (aPL) in systemic lupus erythematosus (SLE) patients.
SLE patients (101) and matched controls (101) were enrolled from 2005 to 2009 and received seasonal influenza vaccinations. Sera were tested by ELISA for aCL at baseline, 2, 6, and 12 weeks after vaccination. Vaccine responses were ranked according to an overall anti-influenza antibody response index. Individuals with positive aCL were further tested for β2GPI antibodies.
SLE patients and healthy controls developed new onset aCL post-vaccination (12/101 cases and 7/101 controls, OR 1.81, p=0.34). New onset moderate aCL are slightly enriched in African American SLE patients (5/36 cases; p=0.094). The optical density (OD) measurements for aCL reactivity in patients were significantly higher than baseline at 2 weeks (p<0.05), 6 weeks (p<0.05), and 12 weeks (p<0.05) post vaccination. No new β2GPI antibodies were detected among patients with new aCL reactivity. Vaccine response was not different between patients with and without new onset aCL reactivity (p=0.43).
This study shows transient increases in aCL, but not anti-β2GPI responses, after influenza vaccination.
PMCID: PMC3268677  PMID: 22235049
Influenza; vaccine; antiphospholipid antibodies; systemic lupus erythematosus
8.  Cell‐ELISA detection of antineuronal antibodies in central nervous system involvement in systemic lupus erythematosus 
Annals of the Rheumatic Diseases  2006;66(4):530-532.
To develop a cell‐ELISA method to detect antineuronal antibodies (anti‐Ns) and evaluate the diagnostic value of anti‐Ns in central nervous system involvement in systemic lupus erythematosus (CNS‐SLE).
Anti‐N was assessed in both serum and cerebrospinal fluid (CSF) samples from 38 patients with CNS‐SLE, 29 with SLE without CNS involvement (non‐CNS‐SLE), 36 with other rheumatic diseases and 59 with non‐rheumatic diseases with the CNS manifestations using a cell‐ELISA method with 1% paraformaldehyde‐fixed SK‐N‐MC neuroblastoma cells as substrate. Serum samples from 37 healthy donors were also included in this study. Patients with CNS‐SLE who were anti‐N positive in CSF were studied serially for CSF anti‐N levels at times of treatment‐associated improvement in CNS symptoms.
Serum anti‐N levels were significantly increased in patients with SLE compared with other groups, with a sensitivity of 61.2% (41/67) and a specificity of 91.8% (p<0.001). CSF anti‐N levels were significantly increased in patients with CNS‐SLE, with a sensitivity of 47.4% (18/38) and a specificity of 89.7%, whereas only 10.3% (3/29) of patients with non‐CNS‐SLE had increased anti‐N in CSF (p<0.001). CSF anti‐N levels decreased significantly after effective treatment of CNS‐SLE (p<0.05).
Serum anti‐N is relatively specific to SLE. CSF anti‐N is a sensitive and relatively specific antibody in diagnosing CNS‐SLE and correlates with CNS‐SLE activity.
PMCID: PMC1856064  PMID: 16905576
9.  Serology of Lupus Erythematosus: Correlation between Immunopathological Features and Clinical Aspects 
Autoimmune Diseases  2014;2014:321359.
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the aberrant production of a broad and heterogenous group of autoantibodies. Even though the presence of autoantibodies in SLE has been known, for more than 60 years, still nowadays a great effort is being made to understand the pathogenetic, diagnostic, and prognostic meaning of such autoantibodies. Antibodies to ds-DNA are useful for the diagnosis of SLE, to monitor the disease activity, and correlate with renal and central nervous involvements. Anti-Sm antibodies are highly specific for SLE. Anti-nucleosome antibodies are an excellent marker for SLE and good predictors of flares in quiescent lupus. Anti-histone antibodies characterize drug-induced lupus, while anti-SSA/Ro and anti-SSB/La antibodies are associated with neonatal lupus erythematosus and photosensitivity. Anti-ribosomal P antibodies play a role in neuropsychiatric lupus, but their association with clinical manifestations is still unclear. Anti-phospholipid antibodies are associated with the anti-phospholipid syndrome, cerebral vascular disease, and neuropsychiatric lupus. Anti-C1q antibodies amplify glomerular injury, and the elevation of their titers may predict renal flares. Anti-RNP antibodies are a marker of Sharp's syndrome but can be found in SLE as well. Anti-PCNA antibodies are present in 5–10% of SLE patients especially those with arthritis and hypocomplementemia.
PMCID: PMC3932647  PMID: 24649358
10.  Somatic mutations in the variable regions of a human IgG anti-double- stranded DNA autoantibody suggest a role for antigen in the induction of systemic lupus erythematosus 
The processes that govern the generation of pathogenic anti-DNA autoantibodies in human systemic lupus erythematosus (SLE) are largely unknown. Autoantibodies may arise as a consequence of polyclonal B cell activation and/or antigen-driven B cell activation and selection. The role of these processes in humoral autoimmunity may be studied by molecular genetic analysis of immunoglobulin (Ig) variable (V) regions of antibodies that are characteristic of SLE. We have analyzed the gene elements that encode a high affinity, IgG anti-double-stranded DNA autoantibody secreted by a monoclonal Epstein-Barr virus (EBV)- transformed cell line derived from a patient with active SLE. In addition, we have identified, cloned, and sequenced the germline counterparts of the VH and VL genes expressed in this autoantibody. The comparison of both sets of gene elements shows that the autoantibody VH and VL regions harbor numerous somatic mutations characteristic of an antigen-driven immune response. The light chain expressed in this autoantibody is a somatically mutated variant of the kv325 germline gene that is frequently associated with paraproteins having autoantibody activity and with Ig molecules produced by malignant B cells that express the CD5 antigen. Furthermore, the utilized DH segment has been repeatedly found in multireactive, low affinity IgM anti-DNA autoantibodies from SLE patients and healthy individuals. These results suggest that pathogenic IgG anti-DNA autoantibodies in human SLE may arise through antigen-driven selection of somatic mutations in the gene elements that frequently encode multireactive IgM autoantibodies.
PMCID: PMC2118793  PMID: 1899104
11.  The Homogeneous Multiplexed System-a New Method for Autoantibody Profile in Systemic Lupus Erythematosus 
Systemic lupus erythematosus (SLE) is a multi-systemic autoimmune disease leading to immunological aberrations and excessive multiple autoantibody production. The aim of this study was to investigate the prevalence of multiple autoantibodies in SLE patients utilizing the multiplex system method.
We analyzed the presence of elevated titers of anti-Ro, anti-La, anti-RNP, anti-Sm, anti-Jo1, anti-centromere, anti-Scl-70, anti-histone, and anti-dsDNA antibodies in 199 serum samples (113 SLE patients, 86 healthy donors). We compared the type, level and number of autoantibodies and the correlation between the autoantibody profile and disease severity utilizing the SLEDAI score.
Elevated titers of at least one autoantibody were detected in 48% of 42 SLE patients. Elevated titers of anti-Ro antibodies were most commonly detected. The distribution of specific autoantibodies was: anti-Ro- 23.8%, anti-dsDNA- 19%, anti-histone- 19%, anti-RNP- 14.2%, anti-La antibodies- 11.9%, anti-Sm- 7.1%, anti-Scl 70-4.7%, and anti-centromere- 2.4%. Utilizing ROC analysis, the sensitivity and specificity of anti-DNA antibodies at a cutoff value of 34 IU/ml were 87.1% and 79.4% respectively. Elevated titers of anti-Jo1 antibody were not detected. There was a correlation with the titer of anti-Ro antibodies and disease activity by the SLEDAI score. Seven patients harbored one autoantibody only, 15 patients harbored 2-3 autoantibodies, 3 patients harbored 4-5 autoantibodies, and one patient harbored 6 autoantibodies. A correlation between the number of autoantibodies per patient and disease severity was found. One patient with a multitude of autoantibodies had severe lupus and a myriad of clinical manifestations.
In conclusion, the multiplex system is specific and sensitive, provides an autoantibody profile in a single test, and may be useful as a diagnostic test for SLE. Elevated anti-Ro antibodies are associated with severe disease. An autoantibody load may be indicative of more severe disease.
PMCID: PMC2270732  PMID: 16050141
12.  International Multicenter Evaluation of Autoantibodies to Ribosomal P Proteins 
Autoantibodies to the ribosomal phosphoproteins (Rib-P) are a serological feature of patients with systemic lupus erythematosus (SLE). The reported prevalence of anti-Rib-P antibodies in SLE ranges from 10 to 40%, being higher in Asian patients. The variation in the observed frequency may be related to a number of factors but is dependent in large part on the test system used to detect the autoantibodies. An association of anti-Rib-P with central nervous system involvement and neuropsychiatric manifestations of SLE has been controversial. In the present international multicenter study, we evaluated the clinical accuracy of a new sensitive Rib-P-specific enzyme-linked immunosorbent assay based on recombinant Rib-P polypeptides. The results showed that 21.3% of 947 SLE patients, but only 0.7% of 1,113 control patients, had a positive test result (P < 0.0001). The sensitivity, specificity, positive and negative predictive values, and diagnostic efficiency were determined to be 21.3%, 99.3%, 95.6%, 62.2%, and 65.3%, respectively. When evaluated in the context of participating centers, the prevalence of anti-Rib-P antibodies was found in descending frequency, as follows: China (35%) > Poland (34%) > Japan (28%) > United States (26%) > Germany (Freiburg; 23.3%) > Denmark (20.5%) > Germany (Berlin; 19%) > Mexico (15.7%) > Israel (11.7%) > Brazil (10%) > Canada (8%). The substantial data from this study indicate that the prevalence of anti-Rib-P antibodies may not be restricted to the genetic background of the patients or to the detection system but may depend on regional practice differences and patient selection. We confirm previously reported associations of antiribosomal antibodies with clinical symptoms and serological findings. Remarkably, we found a lower occurrence of serositis in Rib-P-positive lupus patients.
PMCID: PMC1356623  PMID: 16426003
13.  A prospective study on antiribosomal P proteins in two cases of familial lupus and recurrent psychosis. 
Annals of the Rheumatic Diseases  1990;49(10):779-782.
In two siblings with systemic lupus erythematosus (SLE), who experienced two episodes of psychosis each, a longitudinal study of autoantibodies, including antibodies to ribosomal P proteins, is described. In two of three evaluable periods of 15 weeks antedating psychosis a rise followed by a spontaneous drop in anti-P levels was recorded. In the third period antibodies to ribosomal protein P were absent. It is concluded that results with single samples are not informative, and that frequent measurement of antibodies to ribosomal protein P in patients with SLE may have limited predictive value for psychosis.
PMCID: PMC1004231  PMID: 2241267
14.  Association between anti-nucleophosmin and anti-cardiolipin antibodies in (NZW × BXSB)F1 mice and human systemic lupus erythematosus 
Arthritis Research & Therapy  2005;7(6):R1394-R1403.
We showed previously that nucleophosmin (NPM), a nucleolar phosphoprotein, is recognized by sera from (NZW × BXSB)F1 (WB) mice, a model of systemic lupus erythematosus (SLE) and anti-phospholipid syndrome. In the present study we analysed the prevalence and kinetics of anti-NPM autoantibodies in WB mice by a solid-phase ELISA with recombinant human (rh) NPM as the antigen and showed that most male WB mouse sera had anti-NPM antibodies that were responsible for their indirect immunofluorescence staining pattern on Hep-2 cells. Anti-NPM antibodies were significantly associated with anti-cardiolipin (aCL) antibodies. This antibody profile mirrored that observed in certain human SLE sera because anti-NPM antibodies were detected in 28% of the sera from patients with SLE and were similarly associated with aCL antibodies. The demonstration that rhNPM bound to cardiolipin (CL) in vitro and increased the CL-binding activity of a WB-derived aCL monoclonal antibody indicates that NPM can interact with CL to form SLE-related immunogenic particles that might be responsible for the concomitant production of anti-NPM and aCL antibodies.
PMCID: PMC1297587  PMID: 16277692
15.  Serum levels of autoantibodies against monomeric C-reactive protein are correlated with disease activity in systemic lupus erythematosus 
Arthritis Research & Therapy  2003;6(2):R87-R94.
This study was performed to investigate the relation between IgG autoantibodies against human C-reactive protein (anti-CRP) and disease activity measures in serial serum samples from 10 patients with systemic lupus erythematosus (SLE), of whom four had active kidney involvement during the study period. The presence of anti-CRP was analysed by enzyme-linked immunosorbent assay. The cut-off for positive anti-CRP test was set at the 95th centile of 100 healthy blood donor sera. Specificity of the anti-CRP antibody binding was evaluated by preincubating patient sera with either native or monomeric CRP. Disease activity was determined by the SLE disease activity index (SLEDAI), serum levels of CRP, anti-DNA antibodies, complement components and blood cell counts. Of 50 serum samples, 20 (40%) contained antibodies reactive with monomeric CRP, and 7 of 10 patients were positive on at least one occasion during the study. All patients with active lupus nephritis were positive for anti-CRP at flare. Frequent correlations between anti-CRP levels and disease activity measures were observed in anti-CRP-positive individuals. Accumulated anti-CRP data from all patients were positively correlated with SLEDAI scores and anti-DNA antibody levels, whereas significant inverse relationships were noted for complement factors C1q, C3 and C4, and for lymphocyte counts. This study confirms the high prevalence of anti-CRP autoantibodies in SLE and that the antibody levels are correlated with clinical and laboratory disease activity measures. This indicates that anti-CRP antibodies might have biological functions of pathogenetic interest in SLE. Further prospective clinical studies and experimental studies on effects mediated by anti-CRP antibodies are warranted.
PMCID: PMC400426  PMID: 15059271
autoantibodies; C-reactive protein; disease activity; SLEDAI; systemic lupus erythematosus
16.  Recognition of YKL-39, a human cartilage related protein, as a target antigen in patients with rheumatoid arthritis 
OBJECTIVE—To investigate whether autoimmunity to YKL-39, a recently cloned cartilage protein, occurs in patients with rheumatoid arthritis (RA).
METHODS—Autoantibody to YKL-39 was assayed by enzyme linked immunosorbent assay (ELISA) and western blotting in serum samples from patients with RA, systemic lupus erythematosus (SLE), and healthy donors, using recombinant YKL-39 protein. This reactivity was compared with that against a YKL-39 homologue, YKL-40 (human cartilage gp-39/chondrex), which has been reported to be an autoantigen in RA.
RESULTS—Autoantibody to YKL-39 was detected in seven of 87 patients with RA (8%), but not in serum samples from patients with SLE or healthy donors. YKL-40 reactivity was found in only one of 87 RA serum samples (1%), with no cross reactivity to YKL-39.
CONCLUSION—The existence of anti-YKL-39 antibody in a subset of patients with RA is reported here for the first time. Further, it was shown that the immune response to YKL-39 was independent of that to YKL-40. Clarification of the antibody and T cell responses to autoantigens derived from chondrocyte, cartilage, or other joint components may lead to a better understanding of the pathophysiology of joint destruction in patients with RA.

PMCID: PMC1753367  PMID: 11114282
17.  Clinical and autoantibody correlations in Orientals with systemic lupus erythematosus. 
Annals of the Rheumatic Diseases  1988;47(11):918-923.
Serum samples from 94 patients with systemic lupus erythematosus (SLE) from a medical unit in Singapore were analysed for autoantibodies of 10 different specificities. The prevalence of antibodies to the following antigens was as follows: double stranded (ds) DNA (43%), histone (81%), Sm (26%), nuclear ribonuclear protein (nRNP) (32%), SS-A(Ro) (63%), SS-B(La) (12%), SL/Ki (9%), ribosomal RNP (rRNP) (16%), p70/p80 (5%), proliferating cell nuclear antigen (PCNA) (3%). Except for a higher prevalence of anti-SS-A(Ro), other autoantibodies were within the range reported from Western countries, indicating a high uniformity of autoantibody profiles in SLE in different countries. Patients with neuropsychiatric manifestations showed a higher plurality of antibodies per patient than patients without neuropsychiatric symptoms, 4.22 v 2.77. Patients with anti-Sm were more likely to have active lupus disease. There was no increased prevalence or specific type of autoantibody in those with renal manifestations.
PMCID: PMC1003633  PMID: 3264694
18.  RP105-Negative B Cells in Systemic Lupus Erythematosus 
Systemic lupus erythematosus (SLE) is a multisystem disease characterized by B cells producing autoantibodies against nuclear proteins and DNA, especially anti-double-strand DNA (dsDNA) antibodies. RP105 (CD180), the toll-like receptor- (TLR-) associated molecule, is expressed on normal B cells. However, RP105-negative B cells increase in peripheral blood from patients with active SLE. RP105 may regulate B-cell activation, and RP105-negative B cells produce autoantibodies and take part in pathophysiology of SLE. It is possible that targeting RP105-negative B cells is one of the treatments of SLE. In this paper, we discuss the RP105 biology and clinical significance in SLE.
PMCID: PMC3175410  PMID: 21941580
19.  The Association among Antioxidant Enzymes, Autoantibodies, and Disease Severity Score in Systemic Lupus Erythematosus: Comparison of Neuropsychiatric and Nonneuropsychiatric Groups 
BioMed Research International  2014;2014:137231.
Background. Antioxidative capacity plays an important role in the severity of systemic lupus erythematosus (SLE), which is characterized by autoantibodies. This study aimed to determine the relationship among autoantibody titers, antioxidative stress reserve, and severity of SLE. Methods. The autoantibody titers, clinical markers, antioxidant enzyme levels, and disease activity index (SLEDAI-2k) of 32 SLE patients and 16 healthy controls were compared. We also compared both the neuropsychiatric (NPSLE) and nonneuropsychiatric (non-NPSLE) groups. Results. Superoxide dismutase in red blood cells was significantly lower in the SLE than in the control group. CRP levels are significant higher in SLE patients than in control group (P = 0.034). Among the autoantibodies, anti-U1RNP (P = 0.008), a-Sm (P = 0.027), and anti-ribosomal p (P = 0.028) significantly negatively correlated with glutathione levels. There has no significant correlation between SLE disease activity indexes (SLEDAI) and levels of C3, C4, and antioxidant enzymes. Conclusions. Erythrocyte superoxide dismutase is significantly lower in both NPSLE and non-NPSLE groups. SLE patients have both higher CRP and autoantibodies level and decreased superoxide dismutase level than the healthy control group.
PMCID: PMC4024413  PMID: 24877055
20.  Serum and Cerebrospinal Fluid Autoantibodies in Patients with Neuropsychiatric Lupus Erythematosus. Implications for Diagnosis and Pathogenesis 
PLoS ONE  2008;3(10):e3347.
Despite the uncertainty in the diagnosis of neuropsychiatric involvement in systemic lupus erythematosus (SLE), attempts have been made to record the association of certain antibodies in serum with neuropsychiatric (NP) manifestations. We aimed to assess the behaviour and the association of serum and cerebrospinal fluid (CSF) autoantibodies with NP manifestations in SLE patients (NPSLE).
Methodology/Principal Findings
Forty-seven SLE patients, hospitalized because of NP manifestations were included. They were evaluated at hospitalization and six months later, and serum and CSF samples were obtained at each evaluation. As controls, serum samples were taken from 49 non-NPSLE patients at hospitalization and six months later; serum and CSF samples were also obtained from 6 SLE patients with septic meningitis, 16 surgical SLE patients and 25 patients without autoimmune diseases. Antinuclear, anti-dsDNA, anti-ribosomal P, Anti-N-Methyl-D-Aspartate receptor (NMDAR), anti-cardiolipin, and anti-β2 glycoprotein-I antibodies were measured. In serum, anti-ribosomal P, anti-NMDAR, and other antibodies did not differentiate among SLE groups, and the levels of all antibodies were similar among the SLE groups. Six-months later, this scenario remained unchanged and the decrease in the levels of some autoantibodies reflected a decline in disease activity, rather than a change in NPSLE. In CSF, only the presence and the levels of anti-NMDAR antibodies showed a characteristic distribution in central NPSLE and septic meningitis patients. Six months later the prevalence of most antibodies in CSF did not change, however the levels of anti-dsDNA, anti-ribosomal P, and anti-NMDAR decreased.
In NPSLE, autoantibodies in serum do not reflect their behaviour in CSF. All autoantibodies were elevated in septic meningitis reflecting the global penetration of serum antibodies into the CSF in this condition. Anti-NMDAR antibodies in CSF identified patients with central NPSLE; their continued presence in CSF 6 months after neurologic symptoms raise questions regarding the conditions under which they are pathogenic.
PMCID: PMC2556096  PMID: 18836530
21.  Correlation of antibodies to ribosomal P protein with psychosis in patients with systemic lupus erythematosus. 
Annals of the Rheumatic Diseases  1992;51(9):1053-1055.
Ninety one Japanese patients with systemic lupus erythematosus (SLE) were studied to determine the clinical significance of antibodies to ribosomal P protein (anti-P). Anti-P was detected by western blotting in 38 of 91 patients (42%). Clinical symptoms of SLE were compared between patients with and without anti-P. The occurrence of lupus psychosis was significantly higher in patients with anti-P than in those without anti-P (9/38 v 1/53). No significant association was found between anti-P and other symptoms of SLE. These data strongly support the suggestion proposed by previous workers that anti-P is a marker autoantibody for the development of lupus psychosis.
PMCID: PMC1004836  PMID: 1417136
22.  Anti-serum amyloid component P antibodies in patients with systemic lupus erythematosus correlate with disease activity 
Annals of the Rheumatic Diseases  2005;64(12):1698-1702.
Objective: To determine the presence of raised titres of anti-serum amyloid P component (SAP) antibodies in patients with systemic lupus erythematosus (SLE) and to evaluate their correlation with clinical disease by the SLEDAI and clinical manifestations.
Methods: 452 samples were screened for raised anti-SAP antibody titres by an ELISA. Clinical measures and SLEDAI scores were independently reviewed from medical records. 21 serial samples from 7 patients with SLE were assessed for a change in anti-SAP antibody titres after treatment.
Results: Raised anti-SAP antibody titres were detected in 145/328 (44%) SLE samples. In 112 randomly selected samples, 69/112 (62%) patients had raised anti-SAP antibodies and anti-dsDNA antibody titres, whereas only 32/112 (28%) had raised anti-dsDNA antibody titres without raised anti-SAP antibody titres. The mean titre of anti-SAP antibodies in patients with active disease was higher than in patients with inactive disease and controls. SLEDAI scores, assessed in 54 patients, were raised in 26/31 (84%) patients with raised anti-SAP antibody titres. A SLEDAI score ⩾8 was found in 16/31 (52%) patients with raised anti-SAP antibody titres but in only 5/23 (22%) patients without raised titres. No specific pattern of disease was detected in patients with or without raised titres of anti-SAP antibodies. Serial sampling from patients with active SLE and raised anti-SAP antibody titres showed that anti-SAP antibody titres decreased after treatment and correlated with clinical improvement.
Conclusion: Raised anti-SAP antibody titres detected in patients with SLE correlate with disease activity and decrease with improvement of clinical disease, and thus may serve as an additional prognostic marker.
PMCID: PMC1755319  PMID: 16014675
23.  Anti-ribosomal P protein antibodies detected by immunoblotting in patients with connective tissue diseases: their specificity for SLE and association with IgG anticardiolipin antibodies 
Annals of the Rheumatic Diseases  2000;59(12):975-981.
OBJECTIVE—To assess the prevalence and clinical and serological associations of anti-ribosomal P protein antibodies (anti-P antibodies) in patients with connective tissue diseases (CTDs) and investigate the immunobiological nature of autoantibody clustering in which anti-P antibodies play a part.
METHODS—IgG anti-P antibodies in the sera of 267 patients with CTDs and 31 healthy subjects were analysed by immunoblotting performed on cytoplasmic extract of Raji cells. 60 patients with systemic lupus erythematosus (SLE), 32 systemic sclerosis, 46 primary Sjögren's syndrome, 16 poly/dermatomyositis, 11 rheumatoid arthritis, 8 undifferentiated CTD, 72 overlap CTD, and 22 primary antiphospholipid syndrome were studied. Anti-P antibodies were affinity purified by elution from nitrocellulose bound antigen and tested by ELISA for their binding activity to cardiolipin.
RESULTS—Anti-P antibodies were detected in 16 (6%) patients and in none of the controls: 12/60 SLE (20%) and 4/80 undifferentiated/overlap patients with CTD (5%). A close association of IgG antibodies with P proteins and with cardiolipin was seen in lupus sera (p=0.0009, odds ratio 18.33). Anti-P antibodies from 9 of 12 anti-P lupus serum samples could be affinity purified and none of the affinity purified fractions cross reacted with ELISA plate coated cardiolipin.
CONCLUSIONS—Anti-P immunoreactivity is a specific marker of SLE and lupus-like disease and its detection is recommended as a powerful diagnostic tool. Anti-P antibodies are strongly clustered with IgG anticardiolipin antibodies in lupus sera, even if they are independently elicited. This suggests that their cognate autoantigens play a part in a common pathogenetic pathway in SLE.

PMCID: PMC1753043  PMID: 11087701
24.  Anti-ribosomal P protein IgG autoantibodies in patients with systemic lupus erythematosus: diagnostic performance and clinical profile 
BMC Medicine  2013;11:98.
This study was devised to assess the performance of anti-ribosomal P (anti-Rib-P) antibodies in the diagnosis of systemic lupus erythematosus (SLE) and the association of these antibodies with the clinical features of SLE.
We used a fluorescence enzyme immunoassay to determine anti-Rib-P levels in an SLE group, a rheumatic disease control (RDC) group (rheumatoid arthritis (RA), ankylosing spondylitis, psoriatic arthritis and juvenile idiopathic arthritis), and a healthy control (HC) group. We also determined anti-Smith antigen (anti-Sm) and anti-double-stranded DNA (anti-dsDNA) antibody levels. Receiver operating characteristic (ROC) curves were constructed and the best cut-off points for positivity were determined. Using regression analysis, the relationship between clinical variables and autoantibody levels was analyzed.
In total, 127 patients with SLE, 256 controls with other rheumatic diseases, and 100 HCs were studied. Anti-Rib-P autoantibodies were positive in 18 (14.2%) of the patients with SLE (mean concentration of 30.6 ± 46.9 U/ml) and in 2 patients with RA (0.8% of the RDC group). In addition, 12 patients with SLE (9.4%) were positive for anti-Sm (31.1 ± 40.8 U/ml) and 63 (49.6%) were positive for anti-dsDNA autoantibodies (88.4 ± 88.5 U/ml). When we assessed the 18 patients with SLE who had tested positive for anti-Rib-P, we found that 4 of these were positive for anti-Rib-P only, whereas 12 were positive for anti-Rib-P plus anti-dsDNA, and 2 were positive for all three antibodies. There were no samples positive for anti-Rib-P plus anti-Sm. The specificity, sensitivity, positive likelihood ratio, and negative likelihood ratio of anti-Rib-P for SLE diagnosis were 99.4%, 14.2%, 23.7%, and 0.86%, respectively.
Caucasian ethnicity was associated with lower anti-Rib-P antibody levels. No relation was found between anti-Rib-P levels and neuropsychiatric or other clinical features.
Anti-Rib-P autoantibodies have high specificity for SLE, and measurement of these might improve the accuracy of SLE diagnosis. In this study, we found that Caucasian ethnicity was associated with lower anti-Rib-P antibody levels.
PMCID: PMC3616863  PMID: 23557114
Anti-Rib-P; Systemic lupus erythematosus; Antibodies
25.  Genetic Variation near IRF8 is Associated with Serologic and Cytokine Profiles in Systemic Lupus Erythematosus and Multiple Sclerosis 
Genes and immunity  2013;14(8):10.1038/gene.2013.42.
Alleles of IRF8 are associated with susceptibility to both systemic lupus erythematosus (SLE) and multiple sclerosis (MS). While high type I interferon (IFN) is thought to be causal in SLE, type I IFN is used as a therapy in MS. We investigated whether IRF8 alleles were associated with type I IFN levels or serologic profiles in SLE and MS. Alleles which have been previously associated with SLE or MS were genotyped in SLE and MS patients. The MS-associated rs17445836G allele was associated with anti-dsDNA autoantibodies in SLE patients (meta-analysis OR=1.92). The same allele was associated with decreased serum IFN activity in SLE patients with anti-dsDNA antibodies, and with decreased type I IFN-induced gene expression in PBMC from anti-dsDNA negative SLE patients. In secondary progressive MS patients, rs17445836G was associated with decreased serum type I IFN. Rs17445836G was associated with increased IRF8 expression in SLE patient B cells. In summary, IRF8 rs17445836G is associated with human autoimmune disease characterized by low type I IFN levels, and this may have pharmacogenetic relevance as type I IFN is modulated in SLE and MS. The association with autoantibodies and increased IRF8 expression in B cells supports a role for rs17445836G in humoral tolerance.
PMCID: PMC3856198  PMID: 23965942
systemic lupus erythematosus; type I interferon; autoantibodies; interferon regulatory factors

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