POS0536 REFINING THE SEROLOGICAL SCORES OF THE ACR/EULAR 2010 RHEUMATOID ARTHRITIS CLASSIFICATION CRITERIA: AN INTERNATIONAL STUDY

Background

Rheumatoid factor (RF) and anti-cyclic citrullinated protein/peptide antibodies (ACPA) are included in the ACR/EULAR 2010 classification criteria for rheumatoid arthritis (RA)(1). Both markers are given the same weight in the criteria.

Objectives

As the performance characteristics differ significantly between RF and ACPA(2), we set out to refine the serological scores for RA classification.

Methods

Diagnostic samples from 398 RA patients and from 1073 diseased controls were evaluated with five RF assays (two RF IgM isotype-specific assays and three total RF assays) and five ACPA IgG assays from five different manufacturers.

Results

Firstly, we harmonized thresholds between manufacturers based on predefined specificity for low positive (at 92.5% specificity for RF and at 97.5% specificity ACPA) and high positive results (at 97.5% specificity RF and at 99.0% specificity for ACPA). Next, we determined likelihood ratios (LRs) for RF, ACPA, and combinations of both, for negative, low positive, and high positive results. The LR was higher for ACPA than for RF, for high positive results than for low positive results and for double positivity than for single positivity. Based on these data we refined the weights of serological scores for classification (Table 1).

Table 1.

Refined weights of serological scores for RA classification

RF negativeRF low positiveRF high positiveACPA negative011ACPA low positive233ACPA high positive344

Application of such refined serological weights significantly increased the area under the curve of receiver operating characteristics analysis to distinguish RA from controls, significantly reduced the serological scores in the controls as well as the number of RA misclassifications without affecting the diagnostic sensitivity.

Besides, we showed that combining predefined specificity thresholds with the refined serological scoring, reduced manufacturer-dependent variability in RA classification impacting RA classification for controls from 18.0-29.0% by ACR/EULAR to 11.0-13.0% (significantly increasing specificity) and for RA patients from 67.8-74.0% to 67.6-71.5% (without significantly affecting sensitivity).

Conclusion

Serological weight factors for RA classification can be improved by taking into account the antibody type (RF versus ACPA), the antibody level, and single or combined positivity.

References

[1]Aletaha D, Neogi T, Silman AJ, Funovits J, Felson DT, Bingham COr, et al. 2010 rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Ann Rheum Dis 2010; 69: 1580-8.

[2]Bossuyt X. Anticitrullinated protein antibodies: taking into account antibody levels improves interpretation. Ann Rheum Dis 2017; 76: e33.

Acknowledgements

We thank all participating diagnostic companies for the in-kind support of assays, their technical training and the constructive discussions. Furthermore, we are very thankful to the laboratory technicians of all participating laboratories for their most appreciated assistance in the performance of the RF/ACPA analyses.

Disclosure of Interests

Lieve Van Hoovels Speakers bureau: Thermo Fisher, Consultant of: Thermo Fisher, Grant/research support from: Thermo Fisher, Bert Vander Cruyssen: None declared, Daniela Sieghart Speakers bureau: Thermo Fisher, Consultant of: Thermo Fisher, Carolien Bonroy: None declared, Eszter Nagy: None declared, Rille Pullerits: None declared, Saša Čučnik: None declared, Charlotte Dahle: None declared, Ingmar Heijnen Speakers bureau: Thermo Fisher, Luca Bernasconi Speakers bureau: Thermo Fisher, Farid Benkhadra: None declared, Laura Bogaert: None declared, Stefanie Van Den Bremt: None declared, Ann Vanliedekerke: None declared, Geert Vanheule: None declared, Johan Robbrecht: None declared, Lucy Studholme: None declared, Wirth Claudine: None declared, Rüdiger Müller: None declared, Diego Kyburz: None declared, Christopher Sjowall: None declared, Alf Kastbom: None declared, Rok Jese: None declared, Boja Jovancevic: None declared, Emese Virag Kiss: None declared, Peggy Jacques: None declared, Günter Steiner Speakers bureau: Thermo Fisher, Consultant of: Thermo Fisher, Patrick Verschueren: None declared, Xavier Bossuyt Speakers bureau: Thermo Fisher, Consultant of: Thermo Fisher.

AB0723 Anti-TIF1-beta autoantibodies in a patient with cancer-associated dermatomyositis

Background

Anti-transcriptional intermediary factor 1-gamma (TIF1-gamma) autoantibodies are strongly linked to cancer-associated dermatomyositis (DM). In addition to anti-TIF1-gamma autoantibodies, autoantibodies to TIF1-alpha and TIF1-beta have been described, often coexisting with TIF1-gamma or other known autoantibodies [1,2]. Thus far, anti-TIF1-beta autoantibodies without other known autoantibodies have been identified in only 3 patients with dermatomyositis, of which none had cancer [1,2].

Objectives

To report on a patient with cancer-associated dermatomyositis and isolated anti-TIF1-beta autoantibodies.

Methods

Serum of a patient with cancer-associated dermatomyositis without known autoantibody specificity was evaluated by immunoprecipitation combined with liquid chromatography-tandem mass spectrometry (IP + LC-MS/MS). Mass spectrometry data were matched against the Uniprot Homo Sapiens database with the Mascot search engine using Proteome Discoverer. Additional immunoprecipitation of radiolabeled cell extract followed by autoradiography were performed. Clinical and laboratory data were retrieved from the electronic health record.

Results

TIF1-beta was identified in the immunoprecipitate of the serum of the patient by IP + LC-MS/MS, but not TIF1-gamma or TIF1-alpha. These results were confirmed by immunoprecipitation of radiolabeled cell extract (Figure 1A). The HEp-2 indirect immunofluorescence assay showed a nuclear fine speckled pattern (AC-4, maximum titre > 1/1280, Figure 1B), which corresponds to the subcellular localization of TIF1-beta [3]. The patient, a 64-year old male, presented with dermatomyositis with classical cutaneous and muscular involvement (max. serum creatine kinase level 370 U/l). A renal cell carcinoma was found during the diagnostic work-up for which a partial nephrectomy was performed. There was a good response of both cutaneous and muscular disease activity to treatment with hydroxychloroquine and methylprednisolone.

Figure 1.

A Immunoprecipitation with 35S-methionine labeled K562 cells with subsequent radiography. C Positive control with anti-TIF1-beta and anti-U1-RNP autoantibodies, 1 anti-TIF1-beta-positive patient (patient here described), 2 negative patient, 3 anti-TIF1-gamma/alpha-positive patient B Nuclear fine speckled pattern on HEp-2 indirect immunofluorescence assay, 40X magnification

Conclusion

Isolated anti-TIF1-beta autoantibodies should be considered in patients with dermatomyositis without known myositis-specific autoantibodies and can be associated with cancer.

References

[1]Fujimoto M, Hamaguchi Y, Kaji K, et al. Myositis-specific anti-155/140 autoantibodies target transcription intermediary factor 1 family proteins. Arthritis Rheum 2012;64:513–22. doi:10.1002/art.33403

[2]Satoh M, Chan JYF, Ross SJ, et al. Autoantibodies to transcription intermediary factor (TIF)1β associated with dermatomyositis. Arthritis Res Ther 2012;14:1–8. doi:10.1186/AR3802/FIGURES/2

[3]Thul PJ, Åkesson L, Wiking M, et al. A subcellular map of the human proteome. Science 2017;356. doi:10.1126/science.aal3321

Disclosure of Interests

Jean-Baptiste Vulsteke: None declared, Petra De Haes: None declared, Minoru Satoh: None declared, Ellen De Langhe: None declared, Xavier Bossuyt Consultant of: Inova Diagnostics, Thermo Fisher Scientific

OP0094 IDENTIFICATION OF NEW AUTOANTIGENS IN PATIENTS WITH SYSTEMIC SCLEROSIS THROUGH IMMUNOPRECIPITATION COMBINED WITH LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY

Background

In up to 20% of patients with systemic sclerosis (SSc) none of the established SSc-specific autoantibodies are present [1]. Notwithstanding, in many of these patients high-titer autoantibodies can be detected on the HEp-2 indirect immunofluorescence assay (HEp-2 IIFA) which suggests the presence of an autoantibody to an intracellular protein expressed by the HEp-2 cell line. Immunoprecipitation of unlabeled cell extract followed by gel-free liquid chromatography tandem mass-spectrometry analysis has the potential to identify new autoantigens in an unbiased manner.

Objectives

To identify new autoantigens through immunoprecipitation combined with liquid chromatography-tandem mass spectrometry (IP + LC-MS/MS) in HEp-2 IIFA-positive patients with SSc in whom none of the established SSc-specific autoantibody specificities are present.

Methods

Forty-nine patients from the University Hospitals Leuven that fulfilled the EULAR-ACR 2013 classification criteria for systemic sclerosis or LeRoy and Medsger’s criteria for early systemic sclerosis and who were negative on the EliA CTD Screen (Thermo Fisher Scientific, United States), which includes centromere protein B, topoisomerase I, RNA polymerase III, fibrillarin, PM-Scl and U1 ribonucleoprotein, were identified. Immunoprecipitation was performed by incubation of sera of these patients (1/30 in 300 µl Tris-buffered saline) with Pierce A/G magnetic beads, subsequent cross-linking with bissulfosuccinimidyl suberate (BS3) followed by incubation with nuclear extract of HeLa cells (100-150 µg) overnight at 4°C. The eluted protein was analyzed through liquid chromatography with tandem mass spectrometry. Mass spectrometry data were matched against the Uniprot Homo Sapiens database with the Mascot search engine. Candidate autoantigens were confirmed through immunoprecipitation followed by western blot of the eluate with target-specific polyclonal rabbit antibodies or western blot of recombinant protein incubated with sera of the index patients.

Results

We identified multiple new autoantigens, including the THO complex subunit 1 (THOC1) and other subunits of the THO complex in 3 patients, nuclear valosin-containing protein like-2 (NVL) in 2 patients, nucleolar and coiled-body phosphoprotein 1 (NOLC1) and multiple interacting proteins in 1 patient, probable 28S rRNA (cytosine(4447)-C(5))-methyltransferase (NOP2) in 1 patient, telomeric repeat-binding factor 2 (TERF2) and TERF2-interacting protein (TERF2IP) in 1 patient and regulator of chromosome condensation 1 (RCC1) in 1 patient. The new targets were confirmed through immunoprecipitation-western blot or western blot of recombinant protein incubated with sera (Figure 1). Furthermore, in 10 patients known SSc-associated autoantigens were strongly immunoprecipitated including multiple Th/To subunits in 5 patients, RuvBL1/2 in 2 patients, multiple PM-Scl subunits in 2 patients (who both were negative on the EliA CTD Screen), and fibrillarin in 1 patient (who was also negative on the EliA CTD .).

Figure 1.

Immunoprecipitation-western blot with target-specific rabbit polyclonal antibody (1/500-2000 dilution), numbers corresponding to order of description of patients, HC healthy control. NE nuclear extract. RP recombinant protein WB-RP western blot of recombinant protein incubated with patient’s sera.

Conclusion

Multiple new autoantigens were identified and confirmed in patients with SSc without previously identified autoantibody specificity. Further evaluation of reactivity against the newly identified autoantigens in patients with SSc with known autoantibody specificities and other cohorts is required. IP + LC-MS/MS can identify new and established autoantigens in patients with SSc.

References

[1]Meier FMP, Frommer KW, Dinser R, et al. Update on the profile of the EUSTAR cohort: an analysis of the EULAR Scleroderma Trials and Research group database. Ann Rheum Dis 2012;71:1355–60. doi:10.1136/annrheumdis-2011-200742

Disclosure of Interests

Jean-Baptiste Vulsteke: None declared, Daniel Blockmans: None declared, Petra De Haes: None declared, Steven Vanderschueren: None declared, Patrick Verschueren: None declared, Kristl G Claeys: None declared, Wim Wuyts Grant/research support from: Boehringer-Ingelheim, Galapagos, Roche, Jan Leo Lenaerts: None declared, Ellen De Langhe: None declared, Xavier Bossuyt Consultant of: Inova Diagnostics, Thermo Fisher Scientific.

AB0511 INTERNATIONAL CONSENSUS ON ANCA TESTING AND INTERPRETATION BEYOND SYSTEMIC VASCULITIS

Background:

ANCA can be detected in sera from patients with autoimmune, inflammatory, infectious or neoplastic diseases.

Objectives:

To issue a Consensus Statement on ANCA testing and interpretation beyond systemic vasculitis.

Methods:

This Statement was prepared by a group of experts, based on the results of a comprehensive search in PubMed.

Results:

In certain settings beyond systemic vasculitis, ANCA may have diagnostic, clinical, and/or prognostic relevance. Testing for PR3- and MPO-ANCA by specific immunoassays should be performed in any patient with clinical features suggesting ANCA-associated vasculitis and in patients with anti-GBM disease and idiopathic interstitial pneumonia. Routine ANCA testing is not recommended in patients with connective tissue diseases (CTD), autoimmune liver diseases, inflammatory bowel diseases, infections, and/or malignancy unless there is evidence for small vessel vasculitis. ANCA testing by specific immunoassays may be useful in patients with rheumatoid arthritis, systemic sclerosis or primary Sjögren’s syndrome who have kidney disease with a nephritic sediment or in patients with systemic lupus erythematosus if a kidney biopsy shows prominent necrotizing and crescentic lesions or proliferative lupus nephritis. ANCA testing may be justified in patients with suspected autoimmune hepatitis type 1, who do not have conventional disease-related autoantibodies, or in patients with inflammatory bowel diseases in case of diagnostic uncertainty to discriminate ulcerative colitis from Crohn’s disease. In these cases, ANCA should be tested by indirect immunofluorescence since target antigens are not well characterized. ANCA against bactericidal/permeability-increasing protein may be a biomarker for deteriorating lung function and a poor prognosis in patients with cystic fibrosis.

Conclusion:

ANCA testing is clinically relevant not only in patients with manifestations suggesting systemic vasculitis, but also in patients with certain other disorders, particularly in patients with anti-GBM disease or idiopathic interstitial pneumonia.

Disclosure of Interests:

Sergey Moiseev Grant/research support from: This work was supported by the 5-100 Project, Sechenov University, Moscow, Jan Willem Cohen Tervaert: None declared, Yoshihiro Arimura: None declared, Dimitrios Bogdanos: None declared, Csernok Elena: None declared, Jan Damoiseaux: None declared, Marc Ferrante: None declared, Luis Felipe Flores-Suárez: None declared, Marvin Fritzler: None declared, Pietro Invernizzi: None declared, David Jayne Grant/research support from: ChemoCentryx, GSK, Roche/Genentech, Sanofi-Genzyme, Consultant of: Astra-Zeneca, ChemoCentryx, GSK, InflaRx, Takeda, Insmed, Chugai, Boehringer-Ingelheim, J. Charles Jennette: None declared, Mark Little: None declared, Stephen P. McAdoo: None declared, Pavel Novikov Grant/research support from: This work was supported by the 5-100 Project, Sechenov University, Moscow, Charles D. Pusey: None declared, Antonella Radice: None declared, Alan D. Salama: None declared, Judith Savige: None declared, Mårten Segelmark: None declared, Yehuda Shoenfeld: None declared, Renato Alberto Sinico: None declared, Maria Jose Rego de Sousa: None declared, Ulrich Specks: None declared, Benjamin Terrier: None declared, Athanasios Tzioufas: None declared, Severine Vermeire: None declared, Ming-hui Zhao: None declared, Xavier Bossuyt: None declared

Diagnostic thresholds for free light chains in multiple myeloma depend on the assay used

Leukemia accepted article preview online, 20 November 2017. doi:10.1038/leu.2017.335.

Effect of previous vaccination with pneumococcal conjugate vaccine on pneumococcal polysaccharide vaccine antibody responses

During the past 10 years, pneumococcal conjugate vaccine (PCV) has become part of the standard childhood vaccination programme. This may impact upon the diagnosis of polysaccharide antibody deficiency by measurement of anti-polysaccharide immunoglobulin (Ig)G after immunization with unconjugated pneumococcal polysaccharide vaccine (PPV). Indeed, contrary to PPV, PCV induces a T-dependent, more pronounced memory response. The antibody response to PPV was studied retrospectively in patients referred for suspected humoral immunodeficiency. The study population was divided into four subgroups based on age (2-5 years versus ≥ 10 years) and time tested (1998-2005 versus 2010-12). Only 2-5-year-old children tested in 2010-12 had been vaccinated with PCV prior to PPV. The PCV primed group showed higher antibody responses for PCV-PPV shared serotypes 4 and 18C than the unprimed groups. To a lesser extent, this was also found for non-PCV serotype 9N, but not for non-PCV serotypes 19A and 8. Furthermore, PCV-priming elicited a higher IgG2 response. In conclusion, previous PCV vaccination affects antibody response to PPV for shared serotypes, but can also influence antibody response to some non-PCV serotypes (9N). With increasing number of serotypes included in PCV, the diagnostic assessment for polysaccharide antibody deficiency requires careful selection of serotypes that are not influenced by prior PCV (e.g. serotype 8). Further research is needed to identify more serotypes that are not influenced.

Value of allohaemagglutinins in the diagnosis of a polysaccharide antibody deficiency

Polysaccharide antibody deficiency is characterized by a poor or absent antibody response after vaccination with an unconjugated pneumococcal polysaccharide vaccine. Allohaemagglutinins (AHA) are antibodies to A or B polysaccharide antigens on the red blood cells, and are often used as an additional or alternative measure to assess the polysaccharide antibody response. However, few studies have been conducted to establish the clinical significance of AHA. To investigate the value of AHA to diagnose a polysaccharide antibody deficiency, pneumococcal polysaccharide antibody titres and AHA were studied retrospectively in 180 subjects in whom both tests had been performed. Receiver operating characteristic curves for AHA versus the pneumococcal vaccine response as a marker for the anti-polysaccharide immune response revealed an area under the curve between 0·5 and 0·573. Sensitivity and specificity of AHA to detect a polysaccharide antibody deficiency, as diagnosed by vaccination response, were low (calculated for cut-off 1/4-1/32). In subjects with only low pneumococcal antibody response, the prevalence of bronchiectasis was significantly higher than in subjects with only low AHA (45·5 and 1·3%, respectively) or normal pneumococcal antibody response and AHA (2·4%). A logistic regression model showed that low pneumococcal antibody response but not AHA was associated with bronchiectasis (odds ratio 46·2). The results of this study do not support the routine use of AHA to assess the polysaccharide antibody response in patients with suspected immunodeficiency, but more studies are warranted to clarify the subject further.

There is no benefit in routinely monitoring ANCA titres in patients with granulomatosis with polyangiitis

OBJECTIVES

To analyse the link between antineutrophil cytoplasmic antibody (ANCA) levels and risk of relapse in patients with granulomatosis with polyangiitis (GPA), as the clinical benefit of monitoring ANCA levels is uncertain.

METHODS

A retrospective analysis was made of all charts available from 43 patients diagnosed with GPA, fulfilling The American College of Rheumatology 1990 criteria, and followed between 1994 and 2012 at a general internal medicine department of a university hospital. Clinical and biochemical data (i.e. anti-proteinase 3 (PR3) levels) were collected and correlated.

RESULTS

43 relapses occurred in 25 patients (58.1% of 43 patients). When blood samples are routinely taken at a follow-up visit (i.e. low pre-test probability, ± 5.5%) in the GPA-population, a 75%-increase in the PR3-level or its reappearance has only limited positive predictive value (PPV 15.0% and 22.5% respectively) for predicting relapse. Adversely, when clinical suspicion of relapse is high (i.e. high pre-test probability, for example 50%), an increase of 75% or reappearance of PR3 makes relapse even more likely (PPV 77.5%, 81.6% respectively). Conversely, a high negative predictive value (NPV) of 99.3% and a negative likelihood ratio (LR-) of 0.12 suggest that, in the absence of PR3, relapse is unlikely if patients had detectable ANCAs at diagnosis.

CONCLUSIONS

Routine ANCA monitoring in patients diagnosed with GPA has limited value. However, targeted determination of ANCA levels may be useful if a relapse is clinically suspected (i.e. high pre-test probability).

Belgian recommendations on ANA, anti-dsDNA and anti-ENA antibody testing

Autoantibodies to nuclear antigens, i.e. antinuclear antibodies (ANA), antibodies to double-stranded DNA (dsDNA) and extractable nuclear antigens (ENA), are useful as diagnostic markers for a variety of autoimmune diseases. In March 2010, the Belgian national External Quality Assessment Scheme sent a questionnaire on ANA, anti-dsDNA and anti-ENA antibody testing designed by the Dutch EASI (European Autoimmunity Standardization Initiative) team, to all clinical laboratories performing ANA testing. Virtually all laboratories completed the questionnaire (97·7%, 127/130). This paper discusses the results of this questionnaire and provides valuable information on the state-of-the-art of ANA, anti-dsDNA and anti-ENA antibody testing as practiced in the Belgian laboratories. In addition, this work presents practical recommendations developed by the members of the advisory board of the scheme as a result of the outcome of this study.

The phenotype and genotype of rheumatoid arthritis in the Democratic Republic of Congo

Introduction

Little is known about rheumatoid arthritis in the black, particularly in Congolese, populations. Our objective was to describe the phenotype and genotype of rheumatoid arthritis (RA) in Congolese.

Methods

All consecutive rheumatoid arthritis (RA) patients attending Kinshasa University Hospital in a three-year time period were included. Demographics, clinical features and tobacco consumption were noted. Disease Activity Score (DAS)-28 based on the erythrocyte sedimentation rate (ESR), Health Assessment Questionnaire (HAQ), anti-citrullinated peptide antibodies (CCP) antibodies and rheumatoid factor (RF) were determined. Radiographs were scored according to Sharp-van der Heijde. On a subset of patients and controls HLA-DRB1 typing was performed.

Results

A total of 114 females and 14 males aged 51.2 ± 14.9 were included. Mean duration of symptoms was four years. Moderate tobacco consumption was reported in a minority of patients. DAS-28 at first visit was >5.1 and HAQ ≥0.5 in all patients. X-rays showed joint erosions and/or joint space narrowing, mostly of a moderate grade in 55.8% of patients. Anti-CCP and/or RF were present in 48.6% of patients with available data (n = 72) and in 3.0% of controls (n = 67). Radiographic changes and nodules were more frequent in RF or anti-CCP positive patients. One copy of the shared epitope was found in 13 patients (35.1%) and 3 controls (12.5%). Two copies were found in one patient (2.7%) and in one control (4.2%).

Conclusion

Congolese patients with RA consult long after disease onset. Despite this delay, the majority presents without major damage and is RF, anti-CCP and SE negative. We put forward the hypothesis that besides different environmental factors there is probably also a particular genetic risk profile in Congolese patients, different from the HLA-DRB1 shared epitope.

Treatment of rheumatoid arthritis with methotrexate in Congolese patients

Methotrexate (MTX) is the anchor drug in the treatment of rheumatoid arthritis (RA) but data concerning the effectiveness of treatment with this compound are lacking in the Congolese population. In the present study, the evolution of RA in Congolese patients on MTX treatment is reported from before disease-modifying antirheumatic drug (DMARD) initiation till 20 months later. All consecutive DMARD-naïve RA patients (ACR 1987 criteria) attending the rheumatology unit of the University Hospital of Kinshasa from January 2008 to September 2010 were included. All were treated with MTX (started at 7.5 mg/week) and bridging steroids (started at 30mg/day). Treatment adaptations of MTX and concomitant drugs are reported as well as evolution of disease activity (DAS28-ESR), functionality (Health Assessment Questionnaire), radiological damage, and safety over 20 months. Of 98 patients recruited, more than one third were lost at follow-up. A follow-up visit at 20 months was available for 51 patients. These 48 women and 3 men had a mean age of 51.2 ± 13 years and a mean delay from symptom onset till their first visit of 3.2 years. At 20 months, the average MTX dose was 9.7 mg weekly. A second DMARD was added in three patients. The average dose of prednisone at 20 months was 7.5 mg daily. A significant improvement of DAS28 and functional disability was observed and 35.3 % of patients entered remission (DAS28 <2.6). A progression of X-ray damage was observed in one third of patients. Two patients had to stop MTX because of severe side effects and two patients developed diabetes. Methotrexate and bridging steroids therapy is effective also in sub-Saharan Africa but the average weekly MTX dose remains low. Implementation of a regular follow-up is a major issue.

Immune dysfunction in patients with functional gastrointestinal disorders

There is increasing evidence for involvement of the immune system in functional gastrointestinal disorder (FGID), including onset after acute gastrointestinal infections, genotypes resulting in altered cytokine expression and abnormal presence of immune cells. Our aim was to assess cellular and humoral immune responses in (i) FGIDs, compared to healthy subjects and (ii) acute vs unspecified onset FGIDs. Lymphocytic [interleukin (IL)-5, IL-10, IL-13 and interferon gamma (IFN-gamma)] and monocytic [IL-10, IL-12, tumour necrosis factor (TNF)-alpha] cytokine production was characterized at baseline and after stimulation with phytohemagglutinine and anti-CD28 or lipopolysaccharide (LPS) in controls (n = 32), irritable bowel syndrome (IBS) (n = 30), functional dyspepsia (FD) (n = 23) and non-cardiac chest pain (NCCP) (n = 15). Serum IL-6 and IL-10 concentrations were compared, and the immunophenotype was assessed using fluorescent-activated cell sorter. Findings were compared for acute vs unspecified onset FGID. Compared to controls, stimulated lymphocyte expression of IL-5 and IL-13 was enhanced in IBS, FD and NCCP (all P < 0.05). Conversely, the stimulated monocytic IL-12 and lymphocytic IL-10 expression were reduced in IBS and FD, while IFN-gamma expression was also reduced in FD patients. Except for an increase in the numbers of CD3(+)CD45RA(+)CD45RO(+) cells, no distinct cellular profile was detected. Patients with a presumed acute onset of their symptoms had higher serum IL-10 levels and more CD3(+)CD45RA(+)CD45RO(+) cells, while TNF-alpha levels following stimulation with LPS were higher in FD patients reporting an acute onset. A shift towards a Th2 cytokine profile is present in FGID, while the cellular immunophenotype remains largely unchanged. Further research is indicated and could provide new therapeutic strategies for these disorders.

Isolated IgG3 deficiency in children: to treat or not to treat? Case presentation and review of the literature

Immunoglobulin G3 (IgG3) subclass deficiency has received rather little attention thus far. In this report, the clinical and immunologic characteristics of six children with isolated IgG3 deficiency are discussed. The currently available literature on IgG3 deficiency is reviewed with specific emphasis on the peculiarities of the IgG3 subclass, the clinical relevance of IgG3 deficiency as well as the therapeutic options.

Evaluating the “Leeds criteria” forPseudomonas aeruginosainfection in a cystic fibrosis centre

Four separate categories of chronic Pseudomonas aeruginosa (Pa) infection in children with cystic fibrosis (CF) have been previously defined, based on airway cultures taken over the previous year. The aim of the present study was to evaluate this definition in the current authors' paediatric and adult CF clinic using clinical, immunological and lung function parameters. During follow-up, out of 193 patients, 55 (34%) CF patients had never been infected with Pa, 27 (17%) were free of Pa, 29 (18%) were intermittently infected and 51 (31%) were chronically infected. Disease severity markers, such as lung function, were significantly worse in the chronic group, especially in the paediatric population. Differences in adult patients were smaller and no longer significant. Pa antibodies differed strongly between the groups, and were very high (mean+/-sd 55.4+/-5.5) and highly statistically significant from all other groups in the chronic group. They were low and different from all other groups in the never group (1.8+/-0.6). Pa antibodies did not differ between the free of Pa and the intermittent group. In conclusion, the current authors confirmed an agreement between Pseudomonas aeruginosa status according to the new definition and clinical status, as well as with the level of Pseudomonas aeruginosa antibodies.

Diagnostic characteristics of a gelatin based Waaler-Rose assay (Serodia-RA) for the detection of rheumatoid factor

OBJECTIVE

To evaluate the diagnostic usefulness of a gelatin based Waaler Rose assay (Serodia-RA) for the detection of rheumatoid factor (RF) in rheumatoid arthritis (RA).

METHODS

RF was measured by Serodia-RA and rate nephelometry in 90 patients with RA according to the revised ACR criteria and 102 patients with rheumatological diseases other than RA. Sensitivity, specificity, accuracy, likelihood ratios, and area under the curve using receiver operating characteristics (ROC) analysis were determined for both tests. Agreement between assays was assessed on 1657 consecutive samples.

RESULTS

At equal specificity, Serodia-RA tended to be more sensitive than rate nephelometry (0.66 v 0.58; p = 0.04). ROC plots showed an area under the curve of 0.843 for Serodia-RA and 0.784 for nephelometry, providing further evidence that Serodia-RA was slightly better at differentiating between RA and non-RA arthropathy. Good agreement was found between both assays.

CONCLUSION

Serodia-RA is slightly more accurate than rate nephelometry for the detection of RF in RA, and a combination of both assays only marginally improves the diagnostic usefulness of RF detection. Use of two tests for detection of RF is not recommended. One test for detection of RF together with a more specific test, such as antibodies to cyclic citrullinated peptide, is suggested.

[The effects of physical exercise on the immune system]

Physical exercise has numerous effects on the human body, including the immune system. After strenuous exercise, athletes pass through a period of impaired immune resistance. During this period, athletes are theoretically more susceptible to upper respiratory tract infections, although a causal relation has never been demonstrated. Moderate exercise seems to have a beneficial effect on the immune function, which could protect against upper respiratory tract infections. Exercise has effects on both the humoral and the cellular immune system. Doping products, except glucocorticoids, only have modest effects on the immune system, although erythropoietin may, in rare cases, cause severe side-effects. Glutamine and vitamin C could, hypothetically, prevent the negative effects of strenuous exercise on the immune function, but further studies are needed to demonstrate and explain these effects.

Evaluation of the immune response to pneumococcal capsular polysaccharides

Antibody deficiency is the most common immunodeficiency. In 5% to 10% of the patients with recurrent infections that are evaluated for immunodeficiency, a specific deficiency in the immune response to capsular polysaccharides can be found. Patients with recurrent infections should therefore be tested for their capacity to produce antibodies against anti-capsular polysaccharides. As a clinical test, specific antibody levels are measured before and 14 days after immunization with the 23-valent pneumococcal polysaccharide vaccine. In this article we describe the indications, the method used to measure antibodies to capsular pneumococcal polysaccharide and the way the results have to be interpreted.

Serological markers for prediction of response to anti-tumor necrosis factor treatment in Crohn's disease

OBJECTIVES

The use of monoclonal anti-tumor necrosis factor (TNF) antibodies (infliximab, Remicade) is a new therapeutic approach for severe refractory luminal or fistulizing, Crohn's disease (CD). However, up to 30% of patients do not respond to this treatment. So far, no parameters predictive of response to anti-TNF have been identified. Our aim was to determine whether serological markers ASCA (anti-Saccharomyces cerevisiae antibodies) or pANCA (perinuclear antineutrophil cytoplasmic antibodies) could identify Crohn's patients likely to benefit from anti-TNF therapy.

METHODS

Serum samples of 279 CD patients were analyzed for ASCA and pANCA before anti-TNF therapy. A blinded physician determined clinical response at week 4 (refractory luminal CD) or week 10 (fistulizing CD) after the first infusion of infliximab (5 mg/kg).

RESULTS

Overall, there was no relationship between ASCA or pANCA and response to therapy. However, lower response rates were observed for patients with refractory intestinal disease carrying the pANCA+/ASCA- combination, although this lacked significance (p = 0.067).

CONCLUSIONS

In this cohort of infliximab-treated patients, neither ASCA nor pANCA could predict response to treatment. However, the combination pANCA+/ASCA- might warrant further investigation for its value in predicting nonresponse in patients with refractory luminal disease.

Phosphorylcholine coating offers natural platelet preservation during cardiopulmonary bypass

Return of blood activated by tissue factor is the main culprit for triggering the coagulation cascade. When this activated blood is diverted from the cardiopulmonary bypass (CPB) circuit, it becomes possible to evaluate the effect of surface treatment on platelet and complement activation. Twenty adult patients undergoing elective coronary artery bypass grafting (CABG) were randomly assigned either to a control group (n=10) or to a group in which the CPB circuit was completely coated with phosphorylcholine (n=10). Plasma concentrations of platelet factor 4 (PF4), beta-thromboglobulin (betaTG), C3, C3d, C4, TCC, thrombin generation, haptoglobin and free haemoglobin, as well as blood loss, were measured. No significant differences between the two groups were found for haemolysis and thrombin generation. The mean total release of PF4 and betaTG during CPB was 9338+/-17303 IU/ml/CPB and 3790+/-4104 IU/ml/CPB in the coated group versus 22192+/-13931 IU/ml/CPB (p=0.011) and 8040+/-3986 IU/ml/CPB (p=0.005) in the control group. Blood loss was 30% less in the coated group compared to the control group. Phosphorylcholine coating appears to have a favourable effect on blood platelets, which is most obvious after studying the changes during CPB. Clinically, this effect resulted in a 30% reduction in blood loss.

Quantification of the leukocyte common antigen (CD45) in mature B-cell malignancies

CD45 is a glycoprotein expressed on all lymphohematopoietic cells. Its expression increases during normal B-cell differentiation and remains stable on mature cells. Although it is widely known that CD45 antigen expression is decreased in B-acute lymphocytic leukemia (ALL), only scarce and contradictory information is available on CD45 expression on mature B-cell malignancies. In healthy adults (n = 15), CD45 expression on B lymphocytes was lower than that on T cells. In patients with chronic lymphocytic leukemia (CLL; n = 22), CD45 expression on malignant cells was lower than that on the whole lymphocyte population of healthy adults (n = 28) and on normal B lymphocytes (n = 15). In 6 of the 22 CLL patients, the malignant cell population could be separated from the normal lymphocyte population on the CD45-side scatter (SSC) plot. In 16 CLL patients, there was some degree of overlap between the malignant and normal cells with respect to CD45 expression. For these patients, there was an inverse correlation between CD45 expression on the whole lymphocyte population and the percentage of malignant cells in this population. In two patients with mantle cell lymphoma (MCL), CD45 expression on the malignant cells appeared lower than that on normal B cells and on the whole lymphocyte population. In six patients with hairy cell leukemia (HCL), CD45 expression on hairy cells was comparable to that on the whole lymphocyte population of healthy adults, but slightly higher than that of normal B cells. Evaluation of CD45 expression may help to characterize mature B-cell malignancies.

Monoclonal IgM: difficulties with correct measurement

We describe three monoclonal IgM paraproteins for which nephelometric IgM quantification generated inaccurate results.

Reference values for the five electrophoretic serum protein fractions in Caucasian children by capillary zone electrophoresis

We report age-related reference intervals for capillary zone electrophoresis for children between 1 and 14 years of age.

Comparative study of ASCA (Anti-Saccharomyces cerevisiae antibody) assays in inflammatory bowel disease

BACKGROUND & AIMS

Anti-Saccharomyces cerevisiae antibody (ASCA) is a serologic marker associated with Crohn's disease (CD). Although there is still discussion on its clinical value, several companies each promote their own ASCA assay to be used in the gastroenterologist's practice at considerable expense. The aim of this study was to determine whether different ASCA assays agree sufficiently well for the results to be used interchangeably.

METHODS

Blood obtained from a large cohort of IBD patients with inflammatory bowel disease (IBD; 100 with CD, 100 with ulcerative colitis [UC]) and 178 controls (100 healthy blood donors and 78 patients with non-IBD diarrheal illnesses) was studied with 4 different ASCA assays. Sensitivity, specificity, and positive predictive value were compared. Agreement between assays was evaluated.

RESULTS

Sensitivity of ASCA for CD ranged between 41% and 76%. Sensitivity was inversely related to specificity and positive predictive value. Results correlated well overall (range = 0.54-0.90) and the different ROC curves showed good agreement. When recalculated cutoff points were used, interchangeability increased. However, large differences were seen when absolute values were compared.

CONCLUSIONS

A large range in sensitivities and specificities of ASCA for CD is seen with different ASCA assays, mainly as a consequence of the cutoff value chosen for each individual assay. Although agreement between and within assays is good, caution is important when absolute values are used. Standardization of ASCA measurements is greatly needed.

Diagnostic value of anti-Saccharomyces cerevisiae and antineutrophil cytoplasmic autoantibodies in inflammatory bowel disease

OBJECTIVES

Correct diagnosis of inflammatory bowel disease (IBD), especially the differentiation between Crohn's disease (CD) and ulcerative colitis (UC), is highly important toward treatment and prognosis. Serological markers are noninvasive diagnostic tools that could be of value in differentiating CD from UC, in cases of indeterminate colitis, and in the identification of subgroups in IBD. The aim of this study was to evaluate the diagnostic accuracy of perinuclear antineutrophil cytoplasmic (pANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) for IBD.

METHODS

ASCA and pANCA were studied in a large cohort of consecutive IBD patients (n = 582: 407 CD, 147 UC, and 28 indeterminate colitis), patients with non-IBD diarrheal illnesses (n = 74), and healthy controls (n = 157). An indirect immunofluorescence technique and a standardized ELISA were performed for detection of pANCA and ASCA, respectively.

RESULTS

Prevalence of ASCA and pANCA was high in CD patients (59.7%) and UC (49.7%) patients, respectively. Positivity for both markers was significantly lower in healthy and non-IBD controls. Accuracy data (sensitivity, specificity, PPV, and NPV, respectively) for differentiating IBD from controls are as follows: ASCA+: 60% (243/407), 91% (345/378), 88% (243/276), and 68% (345/509); pANCA+: 50% (73/147), 95% (605/638), 69% (73/106), and 89% (605/679); ASCA+/pANCA-: 56% (229/407), 94% (355/378), 91% (229/252), and 67% (355/533); and pANCA+/ASCA-: 44% (65/147), 97% (620/638), 78% (65/83), and 88% (620/702).

CONCLUSIONS

Specificity of serological markers for IBD is high, but low sensitivity makes them less useful as diagnostic tests. The combination of tests is probably more powerful, although, clinical subgroups still need to be defined. The usefulness of these markers in indeterminate colitis needs to be studied prospectively.

Anti-Saccharomyces cerevisiae antibodies (ASCA), phenotypes of IBD, and intestinal permeability: a study in IBD families

BACKGROUND

Serologic markers anti-Saccharomyces cerevisiae antibodies (ASCA) and antineutrophil cytoplasmic antibodies with perinuclear staining (pANCA) have been proposed to study the immunopathogenesis of IBD. Their measurement may allow better phenotyping of the disease and the detection of subclinical disease.

AIMS

To test the hypothesis that serological markers identify an immunologic trait related to disease susceptibility. We also wanted to test the hypothesis that ASCA is a marker related to abnormal tissue permeation by common antigens.

METHODS

We studied the prevalence of pANCA and ASCA in a large cohort of sporadic and familial inflammatory bowel diseases and their unaffected relatives and spouses. Kinetics of ASCA was studied and the relationship between ASCA and 51Cr-EDTA intestinal permeation was investigated.

RESULTS

ASCA was associated with sporadic Crohn's disease (CD) (63%), with Crohn's patients belonging to pure CD families (62%) and also with their unaffected family members (21%). pANCA was associated with UC (58%). The prevalence of ASCA in CD patients belonging to mixed families was strikingly low (33%). ASCA was a stable marker throughout the disease and was not related to an increased small intestinal permeability.

CONCLUSION

ASCA is strongly associated with familial CD in Belgium, and 21% of healthy family members also display the marker. The association is much weaker in patients belonging to mixed families. ASCA is a stable marker and is not a secondary phenomenon due to increased intestinal permeability.