Immunoreactivity to metal and silica associates with sarcoidosis in Dutch patients.

BACKGROUND: Involvement of metals or silica in the pathogenesis of sarcoidosis has been suggested by several case reports and specific epidemiological studies. However, the combination of occupational exposure and an immunological reaction has not been studied before in a group of sarcoidosis patients and non-sarcoidosis controls. METHODS: In 256 sarcoidosis patients and 73 control patients with obstructive sleep apnea, exposure to metal and silica was assessed using a questionnaire consisting of a complete occupational history subsequently linked to job-exposure matrices. Next, immunoreactivity to aluminium, beryllium, zirconium and silica was determined in 33 sarcoidosis and 19 control patients using a lymphocyte proliferation test. RESULTS: In sarcoidosis, 83 out 256 patients (32.4%) had occupational exposure to metals or silica, compared to 24.7% in the control group (p = 0.21). A significantly higher percentage of the sarcoidosis patients tested showed immunoreactivity to metals or silica compared to the control group (21.2 and 0% respectively, p = 0.039). CONCLUSIONS: Immunoreactivity to silica and metals was only found in sarcoidosis patients, supporting the hypothesis that these antigens may be involved in the pathogenesis of a distinct subgroup of sarcoidosis patients. This indicates that when searching for causative agents in sarcoidosis patients, besides beryllium, also zirconium, aluminium and silica deserve clinical investigation.

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).

Evaluation of a panel of 28 biomarkers for the non-invasive diagnosis of endometriosis.

BACKGROUND: At present, the only way to conclusively diagnose endometriosis is laparoscopic inspection, preferably with histological confirmation. This contributes to the delay in the diagnosis of endometriosis which is 6-11 years. So far non-invasive diagnostic approaches such as ultrasound (US), MRI or blood tests do not have sufficient diagnostic power. Our aim was to develop and validate a non-invasive diagnostic test with a high sensitivity (80% or more) for symptomatic endometriosis patients, without US evidence of endometriosis, since this is the group most in need of a non-invasive test. METHODS: A total of 28 inflammatory and non-inflammatory plasma biomarkers were measured in 353 EDTA plasma samples collected at surgery from 121 controls without endometriosis at laparoscopy and from 232 women with endometriosis (minimal-mild n = 148; moderate-severe n = 84), including 175 women without preoperative US evidence of endometriosis. Surgery was done during menstrual (n = 83), follicular (n = 135) and luteal (n = 135) phases of the menstrual cycle. For analysis, the data were randomly divided into an independent training (n = 235) and a test (n = 118) data set. Statistical analysis was done using univariate and multivariate (logistic regression and least squares support vector machines (LS-SVM) approaches in training- and test data set separately to validate our findings. RESULTS: In the training set, two models of four biomarkers (Model 1: annexin V, VEGF, CA-125 and glycodelin; Model 2: annexin V, VEGF, CA-125 and sICAM-1) analysed in plasma, obtained during the menstrual phase, could predict US-negative endometriosis with a high sensitivity (81-90%) and an acceptable specificity (68-81%). The same two models predicted US-negative endometriosis in the independent validation test set with a high sensitivity (82%) and an acceptable specificity (63-75%). CONCLUSIONS: In plasma samples obtained during menstruation, multivariate analysis of four biomarkers (annexin V, VEGF, CA-125 and sICAM-1/or glycodelin) enabled the diagnosis of endometriosis undetectable by US with a sensitivity of 81-90% and a specificity of 63-81% in independent training- and test data set. The next step is to apply these models for preoperative prediction of endometriosis in an independent set of patients with infertility and/or pain without US evidence of endometriosis, scheduled for laparoscopy.

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.

Comparative study of two cytofluorometric methods of analysis.

Cytofluorometry of lymphocytes is an important technique in experimental biology and clinical medicine. One source of variability in the results with this technique stems from the difficulty of delineating cell subpopulations on a visual basis. We have evaluated the performance of a novel software method (Attractor), which introduces cluster analysis for the more precise definition of cell populations. Using 115 blood samples from patients with various immunological diseases, we compared the results obtained for 19 lymphocyte cell populations employing either the Attractor program or a conventional program (Cellquest). The analysis focused on inter-observer and inter-method variability and comparability. Inter-observer variability was significantly lower with the Attractor software, particularly when quantifying small cell populations such as activated subsets. The results obtained with both methods showed high correlation coefficients except for some cell populations that were either very small or which had to be calculated from the sum of other counts. The performance of the novel flow cytometric software is similar to software programs currently in use, but it offers an advantage for the definition of small and/or activated lymphocyte subpopulations. Moreover, the consistency of the measurements is better. A major disadvantage for statistical analysis, however, is that the Attractor program has not been adapted for non-parametric data.

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.

Monoclonal IgM: difficulties with correct measurement.

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

Screening for autoantibodies to SS-A/RO by indirect immunofluorescence using HEp-2000 cells.

We evaluated indirect immunofluorescence (IF) using HEp-2000 slides, which are transfected with SS-A cDNA, for screening for anti-SS-A antibodies, by comparing it with counterimmunoelectrophoresis (CIE). A total of 2427 specimens were screened for IF reactivity and for SS-A precipitins, of which 1033 (43%) were negative on both IF and CIE. There were 1271 SS-A precipitin-negative specimens (52%) which were IF-positive but lacked the distinctive SS-A staining pattern. One precipitin-negative serum was IF-positive with the distinctive SS-A pattern in the HEp-2000 system. One hundred and twenty-two specimens (5%) were positive for anti-SS-A precipitins on CIE, 107 showed the distinctive SS-A fluorescence staining pattern, whereas 15 of these precipitin-positive samples (12%) were IF-positive but did not display the distinctive SS-A pattern on the transfected cells. Fourteen of the 15 samples in which the distinctive SS-A pattern was not observed displayed other significant antinuclear antibody (titre equal or >1:320) patterns. In conclusion, the presence of the typical 'distinctive' SS-A pattern on IF using the HEp-2000 slides is highly specific for the presence of autoantibodies to SS-A and has a sensitivity of 88% for detecting these antibodies.

[The effects of physical exercise on the immune system]. / Effecten van fysieke inspanning op het immuunstelsel.

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.

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.

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.

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.