Specificity analysis of antibodies to single-stranded micrococcal DNA in the sera of normal human subjects and patients with systemic lupus erythematosus.

To evaluate the properties of antibodies to bacterial DNA in the sera of normal human subjects (NHS) and patients with systemic lupus erythematosus (SLE), the effects of ionic strength and pH on their binding to single-stranded DNA (ssDNA) from Micrococcus lysodeikticus (MC) were measured. By ELISA, antibodies to MC ssDNA in NHS showed greater activity at high ionic strength (0.2-1.0 M) than antibodies in lupus sera. Similarly, antibodies in NHS had higher activity at pH 9 than lupus anti-DNA. Competition binding assays indicated, moreover, that NHS anti-DNA showed greater inhibition by DNA than lupus anti-DNA at comparable inhibitor concentrations. Together, these results suggest that antibodies to MC ssDNA in NHS and SLE sera may differ in their mode of interaction with bacterial DNA and that NHS can generate high avidity antibodies to at least certain DNA determinants.     

Anti-dsDNA antibodies in sera of patients without systemic lupus erythematosus

133 sera of patients without systemic lupus erythematosus (SLE) have been analyzed by an ultramicro ELISA for antibodies to dsDNA. 14 sera (10.5%) had antibody concentrations greater than 120 mU/ml ("positive"). Additionally, 29 sera (21.5%) had antibodies within the range 60 . . . 120 mU/ml ("borderline"). Pathogenetic significance is discussed briefly.     

A subset of antibodies from the sera of patients with systemic lupus erythematosus react with vimentin and DNA.

Sera from patients with systemic lupus erythematosus were tested for the simultaneous presence of antibodies to intermediate filaments (vimentin) and to DNA, using radioimmunoassay and immunofluorescence techniques. Our results indicate that 3 of 17 sera tested contain an IgM population which recognizes an antigenic determinant common to vimentin and DNA by a solid phase immunoassay.     

Monocyte-reactive antibodies in patients with systemic lupus erythematosus.

Cold-reactive antibodies cytotoxic for peripheral monocytes from more than half of normal donors were found in the sera of 2 of 25 patients with systemic lupus erythematosus (SLE) and 1 of 26 with rheumatoid arthritis (RA), and they were absent in 25 normal sera. In contrast, lymphocytotoxic activity for T or B lymphocytes was found in over half of the lupus sera. The antibodies to monocytes were primarily IgM and exhibited varying specificities. Some of the antibodies were directed against antigenic determinants common to monocytes, T and B cells, or against determinants shared between monocytes and one lymphocyte type. One serum possessed a high titer of antibodies that were specific for monocytes. The clinical significance of antimonocyte antibodies remains to be established.     

Use of monoclonal antibodies to identify shared idiotypes on human antibodies to native DNA from patients with systemic lupus erythematosus.

Antinative DNA antibodies were purified from the serum of a patient with active systemic lupus erythematosus. Using hybridoma technology, we produced several mouse monoclonal antibodies directed against idiotypic determinants on these antinative DNA antibodies. One of these monoclonal anti-idiotypic antibodies, 3I, an IgG2a Kappa, was extensively characterized. 3I is believed to be directed against an idiotypic determinant because (i) its reactivity with antinative DNA antibodies is not inhibited by a large excess of pooled human serum, (ii) it reacts with F(ab')2 fragments of antinative DNA antibodies, and (iii) it reacts with antinative DNA antibodies of all IgG subclasses. 3I is not directed against the antigen binding site in that native DNA and 3I do not compete for binding to antinative DNA antibodies. Eight of nine sera containing antinative DNA activity as determined by the Millipore filter assay reacted with 3I in a solid-phase radioimmunoassay. These findings suggest that antinative DNA antibodies from nonrelated patients with systemic lupus erythematosus share a common idiotype.     

Antiganglioside antibodies in patients with neuropsychiatric systemic lupus erythematosus.

Antiganglioside antibodies (AGA) were determined in sera and cerebrospinal fluids (CSF) from 50 systemic lupus erythematosus (SLE) patients, and age-matched normal controls. The SLE patients were subdivided according to the type of clinical manifestation into two groups: neuropsychiatric SLE and active SLE without neuropsychiatric manifestation. The presence of these antibodies showed a significant correlation between IgG AGA in the CSF and IgM AGA in the serum and neuropsychiatric SLE. Fifteen patients had this antibody in the CSF without detectable levels in the serum. No correlation was seen between anticardiolipin antibodies in the serum of CSF and neuropsychiatric SLE. The present work suggests that antibodies against gangliosides may be a marker for neuropsychiatric SLE and that intrathecal antibody production can result in the development of this manifestation.     

Anticardiolipin antibodies in patients with systemic lupus erythematosus

We studied a group of 59 unselected patients with systemic lupus erythematosus (SLE); these patients were from a defined population who lived in southern Sweden. We found that serum concentrations of anticardiolipin antibodies were increased in 32 SLE patients (54.2%). No significant correlation between increased amounts of anticardiolipin antibodies and clinical symptoms, such as thrombocytopenia or thrombosis, was found. Serial serum samples from 28 patients (12 patients were from the epidemiologic cohort) were analyzed. Sixteen of these 28 patients (57.1%) had increased levels of anticardiolipin antibodies; in most cases, there was no variation in these values with regard to clinical disease flares or treatment. Increased concentrations of anticardiolipin were observed in 4 patients with cerebral infarction. However, very high concentrations of anticardiolipin antibodies were observed in several patients with inactive SLE who had no history of thrombosis or thrombocytopenia. Our results underscore the importance of studying unselected patient groups when correlating laboratory data with clinical manifestations of disease.     

Anti-centromere antibodies in patients with systemic lupus erythematosus

BACKGROUND: Anti-centromere autoantibodies (ACA) are frequently detected in systemic sclerosis (SScl), especially in the calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia (CREST) syndrome, in which a prevalence of 55% has been reported. The presence of ACA in systemic lupus erythematosus (SLE) is so rare that its detection can raise serious doubts about the validity of the diagnosis. OBJECTIVE: To determine the frequency of ACA positive subjects from a wide monocentric cohort of SLE patients and analyse the clinical and biological characteristics of this group. METHODS: Five hundred and sixty consecutive SLE patients were systematically analysed for the presence of ACA and other autoantibodies using indirect immunofluorescence, counter-immunoelectrophoresis, double immunodiffusion, enzyme-linked immunosorbent assay (ELISA), and Western-blot. RESULTS: ACA were detected in 11 SLE patients (1.9%); all of them were women. The CENP-B-specific ELISA was positive in all patients. The main clinical features of scleroderma (cutaneous sclerosis, sclerodactylia, digital ulcers, or pulmonary fibrosis) were not present in these patients, who did not differ clinically from the whole SLE group. CONCLUSIONS: ACA can be detected in patients with genuine SLE without concurrent scleroderma. Therefore, the presence of this antibody does not preclude the possibility of the diagnosis of SLE. In addition, SLE patients with ACA do not represent a different clinical subgroup.     

Cross-reactivity of antiidiotypic antibodies with DNA in systemic lupus erythematosus

OBJECTIVE: To assess the functional relationship between antibodies reactive with DNA and antibodies reactive with the idiotypes (idiopeptides) of anti-DNA antibodies that are associated with systemic lupus erythematosus (SLE) in mice. METHODS: Antiidiotypic antibodies that appeared spontaneously in lupus mice, and others that were induced by immunization of normal, non-lupus mice, were analyzed for their reactivity by a range of direct binding, competition enzyme-linked immunosorbent assay (ELISA), and surface plasmon resonance (SPR) methods. Their reactions were assessed against synthetic peptides representing sequences of the V(H) region of anti-DNA monoclonal antibody (mAb) V-88, against the native mAb itself, and against mammalian DNA. RESULTS: In lupus mice, only sera with the highest reactivity against double-stranded DNA (dsDNA) also reacted with idiopeptides in ELISA, and this showed a strong statistical correlation. However, there was no significant relationship between antiidiotypic antibodies and anti-single-stranded DNA antibodies. Immunization of (BALB/c x NZW)F1 mice with idiopeptides p64 (V(H) residues 64-80) or p92 (V(H) residues 92-105) induced antibodies that reacted not only against the respective peptides, but also against the native parent anti-DNA mAb V-88. Furthermore, the immune antiidiopeptide antibodies cross-reacted with dsDNA. Competition SPR experiments with the BIAcore system supported this observation. The binding reaction of V(H) peptide p64 (representing the CDR-H2/FR-H3 region of V-88) with antiidiopeptide antibodies was inhibited by dsDNA. CONCLUSION: This study identified a unique set of autoantibodies in SLE. They react with both autoantibody idiotopes and with dsDNA, thus having a dual specificity for 2 autoantigens. Because these antiidiotope antibodies arise naturally during the development of lupus disease, and because they bind also to dsDNA, this provides a mechanism whereby the production of anti-dsDNA antibodies is stimulated. These idiotopes on autoantibodies in lupus act as natural mimotopes for inducing anti-dsDNA antibodies, which, due to their dual specificity, may significantly contribute to the pathology of nephritis in SLE.     

Anti-Saccharomyces cerevisiae antibodies in patients with systemic lupus erythematosus

Anti-Saccharomyces cerevisiae antibodies (ASCA) had been known to be specific for Crohn’s disease but it has been found in many other autoimmune diseases like systemic lupus erythematosus (SLE). Furthermore, cross-reactive epitopes on β2-glycoprotein I (β2GPI) and Saccharomyces cerevisiae were found in SLE patients. The aims of this study were to evaluate the frequency of ASCA in patients with SLE and to compare it with that of anti-β2GPI antibodies (aβ2GPI). Sera of 116 patients with SLE were analyzed in this retrospective study. All patients fulfilled at least 4 criteria of the 1997 American College of Rheumatology updated criteria for the classification of SLE. Sera of 160 blood donors were included as normal controls. ASCA IgA and IgG and aβ2GPI antibodies were determined by enzyme-linked immunosorbent assays. The frequency of ASCA (IgG and/or IgA) was significantly higher in SLE patients than in control group (31.9 vs. 3.7 %, p < 10^?6). ASCA IgG and ASCA IgA were more frequent in SLE patients than in control group (29.3 vs. 3.1 %, p < 10^?6 and 12.1 vs. 0.6 %, p = 10^?4, respectively). The mean level of ASCA IgG was higher than that of ASCA IgA (9.5 vs. 6.4 U/ml) but the difference was not statistically significant. The frequencies of aβ2GPI (IgG and/or IgA) and aβ2GPI IgA were significantly higher than those of ASCA (IgG and/or IgA) and ASCA IgA (54.3 vs. 31.9 %, p = 5 × 10^?4 and 50.9 vs. 12.1 %, p < 10^?6, respectively). Increased ASCA IgG was observed in patients with SLE, suggesting a role of environmental stimuli in its pathogenesis.     

Anticardiolipin antibodies in patients from Malaysia with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is highly prevalent in Malaysia, which has a mixed population of Malays, Chinese, and Indians. A quantitative enzyme linked immunosorbent assay (ELISA) was used to determine anticardiolipin antibody (aCL) levels (total immunoglobulin, IgG, and IgM) in 200 patients with SLE (164 Chinese, 26 Malay, and 10 Indian) attending the University Hospital of Kuala Lumpur, Malaysia, and 103 matched controls. Only 33 (16.5%) of the patients had raised aCL levels; 26 had raised IgG aCL, five IgM aCL, and two both IgG and IgM aCL. There was a low prevalence of raised levels of aCL in the population studied, which was seen in conjunction with a rare occurrence of thrombosis. The classical association of high aCL levels with thrombocytopenia and recurrent abortions was noted, though not with cerebral disease. The low prevalence of aCL in this study population of mixed racial origin contrasts with findings in European patients with SLE and lends support to the influence of local factors, be they genetic or environmental, on the clinical manifestations of this disease.     

Endothelial cell-binding antibodies in patients with systemic lupus erythematosus

 The implications of endothelial cell-binding IgG antibodies (EC IgG) in systemic lupus erythematosus (SLE) was evaluated by determining level of EC IgG in sera from 112 SLE patients. The serum EC IgG level was determined by the cyto-ELISA method using human umbilical vein endothelial cells (HUVEC), human microvascular endothelial cells (HMVEC), and aortic endothelial cells (HAEC) as antigens. The levels of EC IgG were significantly higher among patients with SLE than among healthy control subjects (P < 0.001), and 68% (76/112) of SLE patients were shown to be EC IgG-positive. In patients with active lupus nephritis, the level of EC IgG was statistically and significantly elevated compared with those without lupus nephritis (P < 0.05). Negative correlations between EC IgG level and levels of CH50, C3, and lymphocyte count were revealed (P < 0.05, P < 0.005, and P < 0.05, respectively). When clinical course was evaluated, the levels of EC IgG correlated with disease activity. Definitive correlations in antibody levels between HUVEC and HMVEC, and between HUVEC and HAEC were revealed (both P < 0.0001). The results of this study revealed that the EC IgG in patients with SLE was involved in the onset of clinical manifestation, especially in patients with active lupus nephritis. Received: January 28, 2002 / Accepted: July 12, 2002 Acknowledgments This investigation was supported by grants from the Research Committee on Intractable Vasculitides, and the Ministry of Health and Welfare of Japan, from 1996 to 2000. Correspondence to:H. Bando     

Antinucleosome antibodies in patients with juvenile systemic lupus erythematosus

Our objective was to evaluate the frequency of antinucleosome antibodies (anti-Ncs) in juvenile systemic lupus erythematosus (JSLE) comparing it to that observed for anti-DNA and to correlate the presence of these antibodies with clinical manifestations and disease activity. Anti-Ncs and anti-DNA were detected by ELISA in 74 patients with JSLE and 64 normal controls. Clinical records were reviewed. Disease activity was assessed by SLEDAI score. Anti-Ncs and anti-DNA showed sensitivity of 52.7% and 54% and specificity of 98.4% and 95.3%, respectively. Disagreement between the two assays was found in 25.7% of the cases: isolated positive Anti-Ncs in nine cases (12.2%) and isolated positive anti-DNA in 10 cases (13.5%). Agreement was found in 74.3%: both positive antibodies in 30 cases and both negative in 25. The presence of anti-Ncs was significantly associated with malar erythema, hemolytic anemia, anti-DNA and low complement levels, but not with renal manifestations. The presence of anti-Ncs was associated with a higher SLEDAI median (P < 0.001) and its titers correlated with the SLEDAI score (r = 0.504; P < 0.001). The frequency, sensitivity and specificity values were similar between anti-Ncs and anti-DNA antibodies in patients with JSLE. Nevertheless, the discordance of 25.7% between the two assays suggests that both antibodies may have a complementary diagnostic role. The association and correlation between anti-Ncs and several disease activity parameters demonstrated its usufulness in the follow-up of these patients.     

Serum thrombomodulin and anticardiolipin antibodies in patients with systemic lupus erythematosus.

Since thrombomodulin (TM) is a specific cell surface glycoprotein for vascular endothelial cells, serum TM (s-TM) might be a useful marker of endothelial cell damage. Antiphospholipid antibodies (aPL) frequently detected in systemic lupus erythematosus (SLE) have been associated with vascular occlusive diseases. Therefore we measured the s-TM in 60 patients with SLE, in 23 patients with other diseases including aPL (disease control group) and in 26 healthy subjects, by means of an enzyme immunoassay using monoclonal antibodies to human TM. A significant positive correlation was found between s-TM and serum creatinine levels in SLE patients (r = 0.813, p less than 0.001). When the s-TM level was divided by the serum creatinine level (TM/Cr) to exclude the effect of renal clearance, the TM/Cr ratios were significantly increased in SLE patients with active lupus nephritis (LN) compared to those without LN (p less than 0.05). The ratios did not correlate with the presence of aPL or antiphospholipid antibody syndrome (APLS) in SLE patients or in the disease control group, although a weak correlation between the TM/Cr ratios and IgG-anticardiolipin antibody titers was found in the SLE patients without LN (r = 0.449, p less than 0.01). The present results suggest that elevated TM/Cr ratios reflect renal and possibly extra-renal endothelial cell damage in SLE patients with active LN, but that s-TM levels do not associate with the presence of aPL or a history of APLS.     

Anticardiolipin antibodies and lupus anticoagulant in Chinese patients with systemic lupus erythematosus

Ninety-one consecutive patients with systemic lupus erythematosus (SLE) were studied. Forty-two patients had positive anticardiolipin antibodies (aCl) 40 aCl-IgG (44.4%); 4 aCl-IgA (4.4%); 1 aCl-IgM (1.1%). One patient had both aCl-IgG and aCl-IgA and 1 patient had aCl-IgG, aCl-IgA and aCl-IgM. Ten patients (11.1%) had lupus anticoagulant (LA). Both aCl isotypes and LA had no statistical association with thrombosis or thrombocytopenia.