Anti-citrullinated protein/peptide antibodies (ACPA) in rheumatoid arthritis: specificity and relation with rheumatoid factor.

Anti-citrullinated protein/peptide antibodies (ACPA) are highly specific and sensitive markers for rheumatoid arthritis (RA). For instance, for the anti-CCP2 assay, sensitivities ranging from 55% to 80% and specificities ranging from 90% to 98% have been reported. Despite their high specificity, recent reports have suggested that ACPA may be found in some patients with other rheumatic autoimmune diseases, including psoriatic arthritis, systemic lupus erythematosus and Sjögren's syndrome. Also, the differences between the classical rheumatoid factor (RF) and ACPA, as well as the complementarity between both tests have recently been demonstrated more clearly. Indeed, both antibody systems have a different association with specific RA features like extra-articular manifestations, a different association with the HLA shared epitope and, behave differently following anti-TNF therapy.

Rheumatoid factor and anticitrullinated protein antibodies in rheumatoid arthritis: diagnostic value, associations with radiological progression rate, and extra-articular manifestations.

BACKGROUND: Autoantibodies such as rheumatoid factor (RF) and anticitrullinated protein antibodies can be detected in rheumatoid arthritis (RA) sera. OBJECTIVE: To determine the diagnostic values of RF, anticitrullinated protein antibodies, and the shared epitope (SE), and their associations with radiological progression rates and extra-articular manifestations. METHODS: Population 1 consisted of sera from 315 patients, consecutively sent for detection of anticitrullinated protein antibodies, of which 264 were used to determine the sensitivity and specificity of RF and of antibodies against three synthetic citrullinated peptides: peptide A (pepA), peptide B (pepB), and CCP2. Population 2 consisted of sera from 180 longstanding RA patients and was used to determine associations of RA associated antibodies and the SE with radiological progression rates and extra-articular manifestations. Antibodies to pepA and pepB were detected by line immunoassay, and antibodies to CCP2 by ELISA. HLA Class II typing was performed by LiPA. RESULTS: In population 1, we defined adapted cut offs corresponding to a specificity of >/=98.5%. This yielded the following sensitivities: RF 12.8%; anti-pepA antibodies 63.6%; anti-pepB antibodies 54.2%; and anti-CCP2 antibodies 73.7%. In population 2, significant differences in radiological progression rates were found between positive and negative patients for different RA antibodies and the SE. RF, but not anticitrullinated protein antibodies or the SE, were more frequent in patients with extra-articular manifestations. CONCLUSION: A valid comparison of RA associated antibodies shows superior sensitivity of the anticitrullinated protein antibodies compared with RF. The presence of RA associated antibodies and the SE are indicative for poorer radiological outcome, and presence of extra-articular manifestations is associated with RF but not with anticitrullinated protein antibodies.

Specific antinuclear antibodies are associated with clinical features in systemic lupus erythematosus.

OBJECTIVES: To study associations between antinuclear antibodies (ANA) and signs/symptoms in patients with systemic lupus erythematosus (SLE). METHODS: A consecutive cohort of 289 patients with SLE was included; 235 fulfilled ACR criteria for SLE and were further analysed. ANA profiles were determined by line immunoassay and by indirect immunofluorescence on Crithidia luciliae. An extensive list of signs/symptoms was evaluated. RESULTS: Five clusters of antibodies were defined by cluster analysis: 1-antibodies to SmB, SmD, RNP-A, RNP-C, and RNP-70k; 2-antibodies to Ro52, Ro60, and SSB; 3, 4, and 5-antibodies to ribosomal P, histones and dsDNA, respectively. Significant associations (p< or =0.01) were found between anti-RNP-70k, anti-RNP-A, anti-RNP-C and Raynaud's phenomenon, between anti-RNP-A, anti-RNP-70k and leucopenia, and between anti-RNP-A, anti-RNP-C and a lower prevalence of urine cellular casts. Anti-SSA, anti-SSB were associated with xerostomia, and anti-SSB with pericarditis. Antibodies to ribosomal P were associated with haemolytic anaemia, leucopenia, and alopecia. Patients with anti-dsDNA antibodies had a higher risk for cellular casts and a lower risk for photosensitivity. Antihistone antibodies were associated with arthritis. CONCLUSIONS: In a large and consecutive cohort of patients with SLE, clusters of antibodies were identified. Previously reported associations of antibodies with symptoms were confirmed and new associations found.

History and diagnostic value of antibodies to citrullinated proteins in rheumatoid arthritis.

Rheumatoid arthritis is a chronic inflammatory joint disease characterized by the presence of autoantibodies. The best known autoantibody is the rheumatoid factor. Another group of antibodies directed against citrullinated epitopes is proven to be more specific for rheumatoid arthritis. This review gives an overview of the history of the different anti-citrullinated protein antibody detection methods and their diagnostic and prognostic properties in RA.

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.

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.

Detection and identification of antinuclear antibodies (ANA) in a large and consecutive cohort of serum samples referred for ANA testing.

OBJECTIVE: To provide data on (a) the probability of detecting antinuclear antibodies (ANA) in a large and consecutive cohort of serum samples referred for ANA testing and (b) the probability of detecting more specific antinuclear reactivities (anti-DNA and anti-extractable nuclear antigens (anti-ENA)) in serum samples with a positive screening test (indirect immunofluorescence on HEp-2 cells). METHODS: Serum samples from 10 550 consecutive patients sent to the laboratory for ANA detection were analysed. In ANA positive serum samples (23.5% of referred serum samples), ANA were identified by indirect immunofluorescence on Crithidia, by immunodiffusion, and by line immunoassay. Because anti-SSA antibodies were the most frequently identified ANA, sensitively detected by line immunoassay, additional immunoassays were developed to confirm the specificity of the line immunoassay result. RESULTS: At least one fine reactivity could be identified in 21.1% of ANA positive serum samples: anti-dsDNA in 3.2%; anti-ENA (anti-SSA 10.5%, anti-SSB 6.7%, anti-RNP 2.7%, anti-Sm 1.8%, anti-Scl70 1.2%, anti-Jo-1 0.2%) in 15.8%, rRNP and anti-Cenp-B in respectively 0.5% and 4.0%. Multiple reactivities were found in 7.9%. For anti-ENA antibodies, line immunoassay was more sensitive than immunodiffusion (15.4% v 7.7%; p<0.0001). The sensitive detection of anti-SSA antibodies by line immunoassay was confirmed by additional assays. CONCLUSIONS: The data from this analysis are useful in estimating the probabilities of detecting specific ANA. Line immunoassay was shown to be a sensitive test for the detection of anti-ENA antibodies.

Specific presence of intracellular citrullinated proteins in rheumatoid arthritis synovium: relevance to antifilaggrin autoantibodies.

OBJECTIVE: To investigate the presence of citrullinated proteins in the synovial membrane of patients with rheumatoid arthritis (RA) and controls, and to analyze a possible relationship with antifilaggrin autoantibody (AFA) reactivity. METHODS: Synovial biopsy samples were obtained from 88 consecutive patients undergoing needle arthroscopy for knee synovitis associated with RA (n = 36), spondylarthropathy (n = 35), osteoarthritis (n = 9), or other diagnoses (n = 8). Tissue sections were stained with 2 different anticitrulline polyclonal antibodies and an antifilaggrin monoclonal antibody (mAb). The phenotype of citrulline-positive cells and the colocalization with affinity-purified AFA were investigated by double immunofluorescence on frozen sections. RESULTS: Studies with the first antibody showed that citrulline is expressed intracellularly in the lining and sublining layers of RA synovial tissue. Staining with the second antibody, monospecific for proteins containing modified citrulline, and with anti-inducible nitric oxide synthetase confirmed the presence of citrullinated proteins rather than free citrulline in the synovium. Citrulline-positive cells were detected in 50% of the RA patients (18 of 36) but in none of the controls (0 of 52). The anticitrulline reactivity colocalized with affinity-purified AFA reactivity, although stainings with the antifilaggrin mAb indicated the absence of filaggrin in the synovium. CONCLUSION: Intracellular citrullinated proteins, which are not recognized by an antifilaggrin mAb, are expressed in RA but not in control synovium. The high specificity of this finding and the colocalization with AFA reactivity boost the interest in citrullinated proteins as possible triggers of autoimmune responses in RA. Moreover, this is the first description of a specific histologic marker for RA synovium.

Occurrence of scleroderma in monozygotic twins.

Familial occurrence of scleroderma is rare and concordance for the disease in twins has been reported exceptionally. We describe 2 female identical twin pairs concordant for scleroderma. The first twin pair was diagnosed with the systemic form of scleroderma, the second pair with the localized form.

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.

Immune-mediated pathology following hepatitis B vaccination. Two cases of polyarteritis nodosa and one case of pityriasis rosea-like drug eruption.

The association of hepatitis B virus infection and vasculitis or other immune-mediated manifestations is well documented. Reports on such manifestations in relation to hepatitis B vaccination are scarce, however. We report 2 patients who developed polyarteritis nodosa following vaccination against hepatitis B. In one patient this resulted in an ischemic and necrotic digital ulcus, necessitating surgical amputation. The other patient presented with typical cutaneous polyarteritis nodosa which responded well to corticosteroid treatment. A third patient developed a severe pityrias rosea-like eruption. He was treated with topical steroids with healing of the lesions, leaving only post-inflammatory hyperpigmentation. The literature on these associations is reviewed.

Analysis of the P wave with signal averaging to assess the risk of atrial fibrillation after coronary artery bypass surgery.

P wave signal averaging was performed in 91 consecutive patients undergoing coronary artery bypass grafting to detect patients at risk of postoperative atrial fibrillation (AF). Sixteen patients (17.5%) developed AF after surgery. The P wave duration on the signal-averaged electrocardiogram (ECG) and on surface ECG was prolonged in AF patients compared to others (respectively 141 +/- 12 vs. 132 +/- 12 ms and 124 +/- 9 vs. 113 +/- 9 ms). The root mean square voltages (RMS) of the total P wave were not different between the two groups; the RMS of the late portion of the P wave (late RMS) was significantly higher (0.25 +/- 0.15 vs. 0.17 +/- 0.10 microV) and the RMS of the first 110 ms of the P wave (early RMS) significantly lower (0.88 +/- 0.28 vs. 1.09 +/- 0.33 microV) in AF. The late/ early RMS ratio was different (0.29 +/- 0.16 vs. 0.17 +/- 0.11). In a multivariate analysis only age and the late/early RMS ratio were predictive for AF.