Optimization and diagnostic performance of a single multiparameter lineblot in the serological workup of systemic sclerosis.

INTRODUCTION: Detection of systemic sclerosis-associated antibodies (SSc-Ab) in routine clinical practice is mostly restricted to anti-centromere and anti-topoisomerase-I antibodies. However, also other SSc-Ab (e.g. anti-RNA-polymerase-III, anti-PM/Scl, anti-fibrillarin and anti-Th/To) have been shown to be valuable diagnostic and prognostic markers for the disease, but testing methodologies for their detection are laborious and time-consuming. This study aimed to optimize interpretational criteria of a multiparameter lineblot (LB) for the parallel detection of SSc-Ab. We also assessed its global diagnostic value as an alternative for combined conventional techniques (CCT) in the serological workup of systemic sclerosis (SSc) patients. METHODS: The presence of SSc-Ab (anti-centromere, anti-topoisomerase-I, anti-RNA-polymerase-III, anti-PM/Scl, anti-fibrillarin and anti-Th/To) was identified by LB on 145 consecutive SSc patients and on 277 disease controls. Diagnostic sensitivity and specificity were calculated for both individual reactivities and the global LB. Cohen's kappa coefficient was used to examine agreement between LB and CCT and guided the definition of final interpretational criteria for LB. RESULTS: Applying the optimal cut-off values and interpretational criteria, LB identified SSc-Ab in 110 SSc patients (sensitivity=76%) and in 19 disease controls (specificity=93%). Globally, there was a substantial agreement between CCT and LB (κ=0.787, concordance 92.4%). LB and CCT showed a very good correlation (κ>0.800) for most SSc-Ab (anti-centromere, anti-topoisomerase-I, anti-RNA-polymerase-III and anti-PM/Scl). The best agreement for anti-RNA-polymerase-III and anti-PM/Scl was achieved when positivity for both components was taken as a criterion. CONCLUSIONS: LB is a reliable alternative for the laborious and time-consuming conventional techniques in the diagnostic workup of SSc, especially for the detection of anti-centromere, anti-topoisomerase-I, anti-RNA-polymerase-III and anti-PM/Scl.

Rituximab in diffuse cutaneous systemic sclerosis: an open-label clinical and histopathological study.

OBJECTIVES: The safety and potential efficacy of rituximab was examined in diffuse cutaneous systemic sclerosis (dc-SSc). METHODS: A 24 week open-label study in which eight patients with dc-SSc received an infusion of 1000 mg rituximab administered at baseline and day 15, together with 100 mg methylprednisolone at each infusion. Assessment included CD19+ peripheral blood lymphocyte number, skin sclerosis score, indices of internal organ functioning, the health assessment questionnaire disability index, the 36-item Short Form health survey and histopathological evaluation of the skin. RESULTS: Ritixumab induced effective B-cell depletion in all patients (<5 CD19+ cells/microl blood). There was a significant change in skin score at week 24 (p<0.001). Also, significant improvements were measured in the dermal hyalinised collagen content (p = 0.014) and dermal myofibroblast numbers (p = 0.011). Two serious adverse events occurred, which were thought to be unrelated to the rituximab treatment. CONCLUSIONS: Rituximab appears to be well tolerated and may have potential efficacy for skin disease in dc-SSc.

Validation of a new screening strategy for anti-extractable nuclear antigen antibodies.

OBJECTIVE: Although indirect immunofluorescence (IIF) is the most widely applied screening test for antinuclear antibodies (ANA), it lacks specificity for the identification of specific diseases or antigen reactivities. The aim of the present study was to validate an anti-extractable nuclear antigen (ENA) screening strategy encompassing a three-step cascade whereby an ELISA with pooled specific ENA is positioned between the IIF and the final anti-ENA identification. METHODS: Sera from 4 populations were tested for anti-ENA using an automated ELISA (EliA Symphony) and a line immunoassay (INNO-LIA ANA update). RESULTS: At the manufacturer's cut-off, a 96% sensitivity (95% CI 94%-98%) and 96% specificity (95% CI 94%-98%) of EliA Symphony for anti-ENA was obtained in a consecutive selection of 328 IIF positive serum samples referred for ANA testing. In addition, a high sensitivity was demonstrated for anti-ENA reactivities in patients with SLE (99%, 95% CI 97%-101%) and SSc (100%), and for anti-ENA monoreactivities. CONCLUSION: The EliA Symphony test was shown to be a sensitive second-line screening test for anti-ENA antibodies. In the context of a high clinical suspicion of connective tissue disease or autoreactivities not included in the EliA Symphony assay, third-line testing may be useful, even if the anti-ENA screening is negative.

Over-representation of construction-related occupations in male patients with systemic sclerosis.

AIMS: Based on preliminary observations, we tested the hypothesis that construction-related occupations are associated with systemic sclerosis (SSc). METHODS: The professional occupation of 91 patients with SSc (71 females and 20 males) was recorded. Categorisation into construction-related and other professions was performed. A double definition was used for construction-related occupations. The first (limited) definition was based upon categories of the Belgian National Institute of Statistics (NIS) occupational list. The following occupations were considered construction-related: electricians, joiners, masons and tilers, plumbers and pipefitters. The use of this list also allows us to compare the distribution of professions in these patients with that in the general population. As the NIS occupational list is limitative and leaves out some "real-life" construction-related occupations, a second and broader interpretation was given to the concept of construction-related occupations. RESULTS: The prevalence of construction-related professions in males with SSc, according to the limited definition, was 10-fold higher than in the general working population (50% vs 5%; p<0.001). Interestingly, most of the patients with construction-related occupations were electricians. In the broader interpretation, 75% of the men with SSc fell into the category of construction-related occupations. CONCLUSIONS: The data show an association between SSc and professional occupation.

Do all anti-citrullinated protein/peptide antibody tests measure the same? Evaluation of discrepancy between anti-citrullinated protein/peptide antibody tests in patients with and without rheumatoid arthritis.

BACKGROUND: Different methods exist to demonstrate anti-citrullinated protein/peptide antibodies (ACPA). AIMS: To evaluate discrepancy between four ACPA tests. PATIENTS AND METHODS: Population 1 consisted of patients with a new diagnostic problem, including 86 patients with rheumatoid arthritis (RA) and 450 patients without RA. Population 2 consisted of 155 patients with RA who had long-standing disease. Population 3 consisted of 188 patients with psoriatic arthritis and in population 4 there were 192 patients with systemic lupus erythematosus. Populations 1 and 2 were tested with the anti-human fibrinogen antibody (AhfibA) test, anti-CCP2 from Eurodiagnostica (CCP2-euro), anti-CCP2 from Pharmacia (CCP2-phar) and anti-CCP3 test by Inova (CCP3). Samples were annotated as discrepant if positive in one and negative in at least one other test. Each discrepant sample was re-analysed in a different run. Populations 3 and 4 were analysed in the CCP2-euro and AhFibA test. RESULTS: In population 1, ACPA positivity was found in 17 of 450 (3.8%) patients without RA; 14 (82%) of these 17 samples were discrepant. In contrast, 61 of 86 (70.9%) patients with RA were ACPA positive of whom 18 of 61 (29.5%) were discrepant (70.9% vs. 29.5%, p<0.001). The discrepancies between tests could be partly attributed to borderline results, inter-assay discrepancy and inter-test variability. They were more prevalent in patients with systemic lupus erythematosus who were ACPA positive than in those with psoriatic arthritis who were ACPA positive. CONCLUSIONS: Discrepancy between different ACPA tests was observed attributable to the occurrence of borderline results, inter-assay variability and mainly to inter-test variability. The lowest inter-test discrepancy is observed between tests that use the same substrate.