Diagnostic associations in a large and consecutively identified population positive for anti-SSA and/or anti-SSB: the range of associated diseases differs according to the detailed serotype

Objective: To determine the diagnostic distribution in a consecutive anti-SSA and/or anti-SSB positive population. Methods: A total of 15 937 serum samples from 10 550 consecutive patients were analysed for antinuclear antibodies (ANAs) on HEp-2 cells. Serum samples positive for ANAs were analysed by immunodiffusion and line immunoassay with recombinant SSA-Ro52, natural SSA-Ro60, and recombinant SSB. Results: Among ANA positive patients in whom clinical information was available, 181 consecutive patients with anti-SSA and/or anti-SSB antibodies were identified, Disease associations were systemic lupus erythematosus (SLE) (45.3%), primary Sjögren''s syndrome (pSS) (14.4%), scleroderma (8.8%), RA (7.7%), cutaneous lupus (7.7%), and dermatomyositis (2.2%). The ratio of diagnoses differed according to the anti-SSA/anti-SSB serotype. Scleroderma and dermatomyositis were enriched among mono-Ro52 reactive serum samples (34.2% and 10.5% respectively). Single reactivity towards Ro60 or anti-Ro60 with anti-Ro52 predisposed for SLE (80.0% and 52.2% respectively). Triple reactivity towards Ro52, Ro60, and SSB was primarily linked with SLE (55.8%) followed by pSS (20.9%). Anti-SSA on immunodiffusion increased the chance for SLE (62.8%), whereas isolated anti-SSB reactivity on immunodiffusion was less indicative for SLE (14.3%) and predisposed more for cutaneous lupus (23.8%) and pSS (33.3%). Conclusion: The diagnostic range associated with anti-SSA or anti-SSB reactivity differs significantly according to the detailed serotype defined by line immunoassay and immunodiffusion.     

Cost-effective detection of non-antidouble-stranded DNA antinuclear antibody specificities in daily clinical practice

OBJECTIVES: To compare the utility of indirect immunofluorescence for the detection of antinuclear antibodies (ANA-IIF) and a fully automated test (ELiA Symphony) that detects antibodies against a mixture of nuclear and cytoplasmic antigens (ENA), to select sera that should be tested for non-antidouble-stranded DNA (dsDNA) antinuclear antibodies in a relatively expensive automated line immunoassay (INNO-LIA ANA update, Lineblot). METHODS: All 328 sera sent to the laboratory for ANA or anti-ENA tests, over a 4 month period were evaluated in all three assays. Results were related to signs and symptoms of systemic autoimmune disease (AID) that patients had before or at the time of blood sampling. RESULTS: Overall, 72 (22%) sera were Lineblot positive. Of 198 patients without clinical manifestations of AID, 7% were Lineblot positive. Limiting Lineblot to sera positive in either ANA-IIF or Symphony tests failed to detect 26 (ANA-IIF) and 22 (Symphony) Lineblot-reactive sera, with 15 sera being negative in both assays. From a clinical point of view, failure to detect these reactivities was not important in most cases. CONCLUSIONS: Restriction of performance of Lineblot to patients with at least one criterion for AID is an ideal and cost-effective strategy. In ignorance of clinical signs and symptoms, screening of sera by ANA-IIF or Symphony strongly reduces the costs of anti-ENA detection, with minimal loss in diagnostic capacity. Based on small differences, including the fact that anti-dsDNA antibodies give a positive ANA-IIF, we prefer screening with ANA-IIF over Symphony.     

Determination of ANA specificity using multiplexed fluorescent microsphere immunoassay in patients with ANA positivity at high titres after infliximab treatment: preliminary results

To evaluate ANA specificity using the fully automated multiplexed fluorescent microsphere immunoassay in patients affected either by rheumatoid arthritis or ankylosing spondylitis who developed strong positivity for ANA as assessed by indirect immunofluorescent method on HEp-2 cells during infliximab treatment. Three men affected by ankylosing spondylitis and 12 women affected by rheumatoid arthritis who developed ANA positivity at high titres during infliximab treatment underwent the identification of ANA specificity by multiplexed fluorescent microsphere immunoassay; moreover anti-DNA and anti-ENA antibodies were tested by indirect immunofluorescence and ELISA method, respectively. In 4 out of 15 cases, the determination of ANA reactivity by multiplexed fluorescent microsphere immunoassay was also performed on the serum collected before infliximab administration. One patient affected by rheumatoid arthritis showed multiple ANA reactivities against SS-A, SS-B, RNP, Sm, Jo-1 and histones; one patient affected by ankylosing spondylitis resulted positive for the same autoantibodies, except for anti-Sm antibody. Moreover, two patients, one with rheumatoid arthritis and one with ankylosing spondylitis, showed single antibody specificity to SS-B and RNP, respectively. The remaining 11 cases did not show any positivity. Instead, all the patients resulted negative for anti-ENA antibodies by the ELISA method. In the four cases tested for ANA specificity by multiplexed fluorescent microsphere immunoassay before and after infliximab administration no difference was found. The search for anti-DNA antibody always resulted negative by both the traditional immunofluorescent assay and the novel technique. The use of multiplexed fluorescent microsphere immunoassay in patients treated with infliximab with ANA positivity at high titres allowed to find some ANA specificities which were not revealed by ELISA method. Nevertheless, the majority of patients resulted negative in spite of ANA positivity at high titres; the molecular target of ANA which develop after infliximab administration still remains to be identified.     

Anti-Ro52 reactivity is an independent and additional serum marker in connective tissue disease

OBJECTIVE: To determine whether anti-Ro52 is an independent serum marker in connective tissue disease. METHODS: Over a two year period, 1727 consecutive antinuclear antibody (ANA) positive serum samples were analysed in parallel by double immunodiffusion with thymus/spleen nuclear extract and by line immunoassay with recombinant Ro52, recombinant La/SSB, and natural Ro60. Sera that were only reactive towards Ro52 were further analysed by a variety of additional anti-SSA/Ro detection methods and by specific anti-Ro52 and anti-Ro60 assays. Natural purified SSA/Ro was analysed by immunoblot and protein sequencing. RESULTS: Analysis of natural purified SSA/Ro (Immunovision, Springdale, AR) showed only Ro60 and no immunoreactive Ro52. Consequently, assays based on this substrate only identify sera with anti-Ro60 reactivity. Twenty serum samples showed anti-Ro52 without anti-Ro60 and anti-SSB/La on line immunoassay. By additional testing, 2/20 sera were found positive for anti-Ro60 reactivity. The remaining 18 sera were not identified by any of the classical anti-SSA/Ro assays and were considered to be reactive only with Ro52 and not with Ro60. This anti-Ro52 reactivity was confirmed by natural and recombinant Ro52 in 16/18 cases. 12/18 sera corresponded to connective tissue diseases. CONCLUSION: Anti-Ro52 positive sera without any evidence of anti-Ro60 and anti-La/SSB reactivity can be considered as an independent group that is systematically missed by classical anti-SSA/Ro detection methods owing to a bias towards anti-Ro60 reactivity. The anti-Ro52 sera are precipitin negative, not retrieved by SSA/Ro enzyme linked immunosorbent assays (ELISAs) based on natural SSA/Ro, and show no specific ANA fluorescence staining pattern. These findings together with the clinical data indicate that anti-Ro52 should be considered as an additional and independent serum marker.     

Utility of age,gender, ANA titer and pattern as predictors of anti-ENA and -dsDNA antibodies

Monovariate and multivariate analyses including logistic regression were performed to determine associations among predicting variables [age, gender, immunofluorescence pattern, and anti-nuclear antibody (ANA) titer] and anti-extractable nuclear antigen (ENA) and -dsDNA antibodies (Abs) in 1089 patients with positive fluorescent ANA (FANA) test results. Samples with high titer ANAs had an increased frequency of anti-ENA and -dsDNA Abs. The receiver operating (ROC) curves of the ANA titer for anti-ENA Abs had a larger under the curve area compared to the ROC curve for anti-dsDNA Abs, indicating that ANA titer is better for predicting anti-ENA Abs than anti-dsDNA Abs. There was no relation noticed between immunofluorescence patterns and anti-ENA and -dsDNA Abs except an increased frequency of anti-dsDNA Abs found in samples with a homogeneous pattern. Probability calculations on the basis of the ANA pattern and the titer showed that samples with low titer ANAs (1:160 or less) had low probabilities for anti-ENA Abs (0.002–0.009) regardless of immunofluorescence patterns. However, samples with a homogeneous pattern at any titers including low titers had high probabilities for anti-dsDNA Abs. A decreased frequency of anti-dsDNA Abs as measured by Crithidia assay was noticed in samples from patients aged 50 or older. In contrast, no association was noticed between age and anti-ENA Abs. There was no female preponderance found in the presence of anti-ENA and -dsDNA Abs. In conclusion, our study shows that the ANA titer but not the immunofluorescence pattern is useful in predicting anti-ENA Abs. In contrast, both the ANA titer and the immunofluorescence pattern help in predicting anti-dsDNA Abs. Samples with low titer ANAs (1:160 or less) may not need a further test for anti-ENA Abs unless an ANA-associated disease is highly suspected. However, a test for anti-dsDNA Abs should be considered in samples with a homogeneous pattern at any titer including low titers.     

Sensitivity of the HEp-2000 Substrate for the Detection of Anti-SSA/Ro60 Antibodies

Anti-SSA/Ro antibodies are the most prevalent type of antinuclear antibody (ANA). Anti-SSA/Ro-positive sera may recognise two proteins: a 52 kDa (Ro52) and a 60 kDa (Ro60) subunit. We studied the sensitivity for Ro60 detection using the HEp-2000 substrate, which consists of HEp-2 cells transfected with Ro60 cDNA in an anti-SSA/Ro-positive population consecutively identified by double immunodiffusion (DID) with thymus/spleen nuclear extract and line immunoassay (LIA) with recombinant Ro52 and Ro60. One hundred and twenty-seven consecutive anti-SSA/Ro-positive sera defined by DID with thymus/spleen nuclear extract and LIA using recombinant Ro52 and Ro60 were analysed on HEp-2000 and DID with natural Ro60. Of these, 91 were anti-Ro60 positive on LIA and/or DID with natural Ro60. The HEp-2000 substrate detected 70/91 (sensitivity 77%) and correlated strongest with DID. Most of the missed anti-Ro60-positive sera had high ANA intensity. The substrate did not detect monospecific anti-Ro52 antibodies (sensitivity 9.7%; 3/31). HEp-2000 substrate can therefore be considered a reliable, simple and alternative method for DID in the detection of anti-Ro60 reactivity. Special follow-up should be given to sera with strong ANA patterns in which the SSA/Ro60 staining pattern may be hidden. Received: 7 May 1999 / Accepted: 12 January 2000     

Utility of anti-Sm,anti-RNP,anti–Ro/SS-A,and anti–La/SS-B (extractable nuclear antigens) detected by enzyme-linked immunosorbent assay for the diagnosis of systemic lupus erythematosus

Objective. To determine the utility of anti-extractable nuclear antigen (anti-ENA) antibodies detected by enzyme-linked immunosorbent assay as a predictor for the diagnosis of systemic lupus erythematosus (SLE). Methods. Among 2,185 serum samples sent for testing for antinuclear antibodies (ANA) by indirect immunofluorescence, 259 consecutive patients with positive ANA were identified. Medical charts of these patients were reviewed to assess the clinical diagnosis, with the reviewer having no knowledge of the anti-ENA result. Clinical data were abstracted for all patients, and diagnoses established using American College of Rheumatology criteria. The utility of ENA antibodies in the diagnosis of SLE was determined by univariate and multivariate analysis among all patients who were positive for ANA, patients who were positive for ANA and for anti-double-stranded DNA (anti-dsDNA), and patients who were positive for ANA and negative for anti-dsDNA. Clinical differences between SLE patients with and those without anti-ENA antibodies were assessed. Results. Anti-ENA antibodies, especially anti-Ro/SS-A, showed strong predictive diagnostic value among ANA+/anti-dsDNA– patients, but were of no utility among ANA+/anti-dsDNA+ patients. The only clinical manifestations that were more common among anti-ENA+ SLE patients were pleuritis and the use of hydroxychloroquine. Conclusion. The presence of anti-ENA antibodies, especially anti-Ro/SS-A, is a useful predictor for the diagnosis of SLE, primarily among patients attending a referral rheumatology center who are positive for ANA and negative for anti-dsDNA. No major clinical differences were noted among ANA+ SLE patients with versus those without ENA.     

Clinical differences between ANA/anti-ENA positive or negative primary Sjögren's syndrome

Summary Fifty female patients with primary Sjögren's syndrome diagnosed according to the Copenhagen criteria were evaluated for both glandular and extraglandular involvement. They were divided into two groups based on the presence or absence of antinuclear and anti-ENA antibodies (ANA/anti-ENA). ANA/anti-ENA negative patients presented with milder and later glandular and extraglandular disease and required less frequent corticosteroid treatment. No significant differences were noted in extraglandular manifestations with the exception of leukopenia which was noted only in ANA/anti-ENA positive cases.     

Comparison study of bead-based and line-blot multiplex ANA immunoassays in the diagnosis of systemic autoimmune rheumatic diseases

Clinical Rheumatology - Detection of antinuclear antibodies (ANA) by immunofluorescence assay (IFA) is increasingly substituted by multiplex bead-based immunoassay (MBA) and line-blot immunoassay...     

Diagnostic and prognostic significance of different antinuclear antibodies in more than 1000 consecutive Albanian patients with rheumatic diseases.

In an unselected population of 1390 consecutive Albanian patients with rheumatic diseases (RD) and other miscellaneous non-rheumatic diseases (MNRD), for whom antinuclear antibody (ANA) testing was requested, we calculated the diagnostic sensitivity, specificity and positive predictive value (PPV) of ANA positive results, ANA titres over 1:100, anti-native DNA (nDNA), anti-Sm, anti-U1 RNP, anti-SSA (Ro) anti-SSB (La) and anti-non-identified extractable nuclear antigen (NIENA) antibodies. The PPVs of these ANA types were found to be appreciable only for systemic lupus erythematosus (SLE); only the positive predictive value of ANA for SLE (26.4%) was lower than that for RA (34.3%). The anti-snRNP (Sm/U1RNP) positive SLE patients were more likely to have over 4 of the ARA criteria for SLE, ANA titres over 1:100, and anti-nDNA antibodies, in contrast with the anti-snRNP negative subgroup. On the other hand, the anti-ENA positive and anti-nDNA positive SLE patients generally showed higher frequencies of renal disease, over 4 of the criteria for SLE and ANA titres over 1:100, compared to anti-ENA positive and anti-nDNA negative patients. Our data suggest that the association of anti-snRNP antibodies with a more severe form of SLE is not to be attributed to these antibodies themselves, but rather to their close association with the concomitant presence of anti-nDNA antibodies.     

Serum immune complexes in systemic sclerosis: relationship with precipitating nuclear antibodies.

In a comparative study of antinuclear antibodies (ANA) and immune complexes in the serum of 43 patients with systemic sclerosis (SS) ANA were detected by indirect immunofluorescence on Hep 2 cells and/or double immunodiffusion in 90% of patients, while immune complex assays were positive in 32% of patients. The immune complex assays were positive only in sera containing antibodies to Scl 70, n-RNP, Ro, and La. The presence of immune complexes in SS sera is therefore related to ANA specificity. This might explain the variable findings of several previous studies of immune complexes in SS.     

Detection of anti-nuclear antibody by immunofluorescence assay and enzyme immunoassay in childhood systemic lupus erythematosus: experience from Bangladesh

Background: Systemic lupus erythematosus (SLE) is a multisystem, chronic but often episodic, autoimmune disease that is characterized by the presence of antinuclear antibodies (ANA). The criteria set by American College of Rheumatology are widely used for diagnosis of SLE. Elevation of ANA titer is the most sensitive of the ACR criteria. There are different methods for detection of ANA. Indirect immunofluorescence (ANA‐IFA) and enzyme immunoassay (ANA‐EIA) are commonly used methods. The sensitivity of ANA‐IFA using HEp‐2 cell substrate is 90–100% in systemic rheumatic diseases. In Bangladesh most of the laboratories use ANA‐EIA for detection of ANA. As the sensitivity of ANA‐EIA is lower than ANA‐IFA it might be that we are missing many cases of ANA positivity in childhood SLE cases. Objectives: To detect ANA by immunofluorescence assay using HEp‐2 cell substrate and enzyme immunoassay in childhood SLE and to compare the diagnostic performance of these methods. Material and methods: This is a cross‐sectional analytical study. A total of 40 patients were enrolled. Among them 20 were childhood SLE cases. Another 20 patients of childhood rheumatic diseases other than SLE were taken as the disease control group. Result: In childhood SLE cases, 100% were ANA‐positive by IFA and 55% were ANA positive by EIA. The sensitivity of ANA‐IFA was 100%. In contrast, sensitivity of ANA‐EIA was 55%. Conclusion: ANA‐IFA is superior to ANA‐EIA for detection of ANA in childhood SLE patients. ANA‐IFA should be the primary screening test for children with clinical features suggestive of SLE.     

Antinuclear antibody testing in pleural fluid for the diagnosis of lupus pleuritis

We sought to determine whether measuring antinuclear antibodies (ANA) and their specificities [dsDNA, extractable nuclear antigens (ENA)] on pleural fluid may contribute to the differential diagnosis of pleural effusions. ANA were tested by indirect immunofluorescence on Hep-2 cells in the pleural fluid of 266 patients with effusions of different etiologies, including 15 lupus pleuritis. The cutoff value for diagnostic use was set at 1:160. Pleural fluid analysis of specific autoantibodies, such as anti-dsDNA and anti-ENA, was also performed if a positive ANA test was obtained. All patients with lupus pleurisy and 16 of 251 (6.4%) patients with pleural effusions secondary to other causes were ANA positive. Fifty-six percent of the positive ANAs in non-lupus pleural fluids were due to neoplasms. The pleural fluid ANA titers were low (< or = 1:80) or absent in two patients with systemic lupus erythematosus (SLE) and effusions due to other factors. Whereas ANA staining patterns in pleural fluid did not help to discriminate lupus pleuritis from non-lupus etiologies, the absence of pleural fluid anti-dsDNA or anti-ENA favored the latter. ANAs in pleural fluid provided no additional diagnostic information beyond that obtained by the measurement in serum and, therefore, these tests need not be routinely performed on pleural fluid samples. However, in patients with SLE and a pleural effusion of uncertain etiology, lack of ANAs or specific autoantibodies in pleural fluid argues against the diagnosis of lupus pleuritis.     

Clinical significance of antinuclear antibodies in malignant diseases: association with rheumatic and connective tissue paraneoplastic syndromes

Our objective was to determine the prevalence of antinuclear antibodies (ANAs) in patients with malignancies and to investigate if their presence might be related with development of musculoskeletal symptoms or paraneoplastic rheumatic syndromes. Antinuclear antibodies were determined by indirect immunofluorescence on Hep-2 cells in 274 neoplastic patients and in a control group of 140 age-adjusted healthy subjects. Antinuclear antibody specificities (anti-DNA and anti-ENA) were investigated in patients with rheumatological symptoms and positive ANA. Antinuclear antibodies were detected in 76 of 274 (27.7%) patients with malignancies and in nine of 140 (6.4%) healthy subjects. Twenty patients reported paraneoplastic rheumatic symptoms or syndromes. Two of them developed clinical symptoms mimicking rheumatoid arthritis (rheumatoid-like arthropathy), one systemic lupus erythematosus (lupus-like syndrome), one dermatomyositis and four cutaneous vasculitides. Musculoskeletal symptoms and paraneoplastic rheumatic symptoms and syndromes were both more frequently observed in patients with positive ANA. Antinuclear antibody specificities were found in only two cases. We can conclude that there is an increased incidence of antinuclear antibodies in malignant conditions. Musculoskeletal symptoms and rheumatic paraneoplastic symptoms and syndromes seem to be more frequent in patients with cancer-related positive ANAs. The failure to find ANA specificities (anti-ENA, anti-DNA) in patients with malignancies and positive ANAs in our study may simply reflect molecular differences between the autoantigens involved in cancer and those characteristically involved in the systemic autoimmune diseases.     

Clinical subsets of scleroderma: relevance of fluorescent and precipitating antinuclear antibodies

Sera from 7 patients with localized and 35 with systemic scleroderma were studied for the presence of fluorescent antinuclear antibodies (FANA) (by indirect immunofluorescence on HEp-2 cells) and antibodies to extractable nuclear antigens (anti-ENA) (by immunodiffusion - ID - and counterimmunoelectrophoresis - CIE). In localized disease, antinuclear autoimmunity was limited to 1 FANA positive serum (14%); in systemic disease, the prevalence of FANA was 94% and that of anti-ENA ranged from 29% to 49% (by ID and CIE, respectively). The commonest ENA system, Scl-70, could be easily detected by CIE, in spite of the reported basic nature of the antigen. The anticentromere antibody occurred only in patients with acrosclerosis (7/26-27%), whereas the association of nucleolar + homogeneous FANA, as well as the anti-Scl-70, were found more frequently in diffuse scleroderma (9/9-100% and 6/9-67%, respectively). The presence of the anticentromere antibody excluded that of any anti-ENA, while a close association was found between nucleolar + homogeneous FANA and the anti-Scl-70. Pulmonary involvement was significantly more frequent in nucleolar + homogeneous FANA positive patients; moreover, in two cases the same pattern proved to predict the development of diffuse scleroderma.     

Autoantibodies in juvenile dermatomyositis

Fourteen patients with juvenile dermatomyositis (JDM) have been investigated for the presence of several serum autoantibodies: antinuclear (ANA), anti-single-stranded and double-stranded DNA, anti-histones, anti-Sm, anti-ribonucleoprotein, anti-SSA/SSB, anti-PM-1, anti-Jo-1, anti-mitochondrial, anti-smooth muscle, anti-gastric parietal cells, anti-cardiolipin (ACA) antibodies and rheumatoid factor. Patients were negative for all autoantibodies except for ANA and ACA. ANA were detected in 50% of the patients when tested on rat liver, but the percentage of positivity rose to 86% when HEp-2 cells were used as substrate. This finding suggests that HEp-2 cells represent a more sensitive substrate than rat liver for the detection of ANA in JDM. Three patients were positive for ACA; two of these presented vascular complications, thus suggesting a possible relationship between ACA and vascular involvement in JDM.     

Detection and differentiation of autoantibodies to extractable nuclear antigens with immunoenzyme tests

Nuclear antigens were extracted from calf thymus with phosphate-buffered saline The 60-80% ammonium sulfate fraction (ASF) of thymus extract contained SS-B-, the 30-60% ASF Sm- and U1-RNP-, and the chromatographically purified 30-60% ASF only Sm antigen. With these fractions enzyme immunoassays were developed for quantitative determination of Sm-, U1-RNP-, and SS-B autoantibodies. Out of 144 sera with antinuclear antibodies 85% were positive in the enzyme immunoassays, 41% in immunofluorescence tests on liver sections (12% speckled, 29% homogeneous immunofluorescence pattern), and 10% in Ouchterlony tests. 26% of the sera were positive in enzyme immunoassays and immunofluorescence tests. All antibody specificities detected by immunodiffusion could be confirmed by enzyme immunoassay. The enzyme immunoassay is far more sensitive then immunodiffusion and in contrast to immunofluorescence allows antibody specificities to be determined. Enzyme immunoassays are recommended for the diagnosis of rheumatic diseases.     

Clinical significance of antinuclear antibodies. Comparison of detection with immunofluorescence and enzyme-linked immunosorbent assays

Objective. To compare the measurement of antinuclear antibodies (ANA) by immunofluorescence and by 6 different commercial enzyme-linked immunosorbent assays (ELISAs) in clearly defined patient groups and serum samples. Methods. Serum samples were derived from 3 sources: 1) patients with a known clinical diagnosis of systemic lupus erythematosus (SLE) (group 1), 2) sera with known monospecific ANA reactivity (group 2), and 3) sera from consecutive patients for whom ANA testing had been ordered (group 3). Each of these sera was tested for the presence of ANA by immunofluorescence on HEp-2 cells, and by using each of 6 commercially available ELISA ANA kits. Results. In patients with known clinical SLE, 88% were ANA positive by immunofluorescence. Positivity with the different ELISAs ranged from 62% to 90%. While most ELISAs successfully detected antibodies to SS-A, RNP, and Sm, there were significant differences between assays in the detection of anticentromere antibodies and anti-DNA. Measurement of ANA in consecutive patients for whom an ANA test was requested showed that, generally, those assays with high sensitivity for detection of SLE had a high false-positive rate, whereas those assays with a low false-positive rate failed to identify some patients with a clinical diagnosis of SLE. Conclusion. There are significant differences in the detection of ANA by immunofluorescence and different ELISA kits. Agreement between different assays is generally marginal. When ordering and interpreting an ANA test, the clinician must be familiar with the specific assay being used to measure ANA and the differences between the various ANA assays.     

Racial differences in the distribution of systemic sclerosis–related serum antinuclear antibodies

Objective. To determine racial differences in the frequencies of systemic sclerosis (SSc)–related serum antinuclear antibodies (ANA). Methods. We tested serum samples from 275 Japanese, 416 North American Caucasian, and 24 North American black SSc patients for 8 SSc-related serum ANA, using indirect immunofluorescence, double immunodiffusion, and radioimmunoprecipitation assays. Results. In comparing the 3 racial groups, we found that anti–U1 RNP, anti–RNA polymerase I, II, and III, and anti–U3 RNP antibodies were the most frequently detected antibodies in Japanese, Caucasian, and black patients, respectively. Anti–PM-Scl antibody was found exclusively in Caucasians. Conclusion. The production of SSc-related serum ANA is related to immunogenetic background.     

Is there a predisposition for the development of autoimmune diseases in patients with fibromyalgia? Retrospective analysis with long term follow-up

The objectives of the study were to evaluate the prevalence of antinuclear antibodies (ANA) in patients with fibromyalgia (FM) and the probability of the development of clinically overt connective tissue diseases. Four hundred and fifty FM patients were compared to 129 healthy matched blood donors. ANA testing was performed by immunofluorescence on rat tissue sections; in case of highly positive results, ANA were specified further by ELISA and immunodiffusion. All ANA positive FM patients were invited for a control examination. The ANA negative patients received a questionnaire, which was designed to identify those patients with possible connective tissue diseases (CTD). There was no significant difference in the frequency of ANA or thyroid antibodies between patients and controls (11.6% vs. 7%). Two patients had developed SLE: one was already ANA/anti-dsDNA positive at time of first diagnosis of FM; in the other, specific antibodies and SLE-related symptoms developed after 4.5 years. The probability for FM patients to develop CTD (SLE) within one year is 0.0027%, which is comparable to the incidence of SLE in the general population (0.005%). The risk of CTD is not increased in FM. The detection of ANA does not predict the development of CTD. However, in individual cases, FM may be an early sign of an autoimmune disease.