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Xavier Bossuyt

Publications and source records attributed to Xavier Bossuyt.

54 records · Page 3Linked to original sources
PubMed2004

Clonal proliferation of T-Cell large granular lymphocytes.

BACKGROUND: T-cell large granular lymphocyte (T-LGL) leukemia is a disorder only rarely reported in children. We diagnosed a new case of a clonal T-LGL proliferation in a 6-year-old girl presenting with severe neutropenia and pure red blood cell aplasia (PRCA). PROCEDURE: Flow cytometric analysis including TCR-Vbeta repertoire analysis and molecular studies using reverse transcriptase polymerase chain reaction (RT-PCR), PCR heteroduplex analysis and GeneScan analysis were performed to investigate the clonal nature of the T-LGL. RESULTS: Flow cytometric analysis revealed a Vbeta3 clonal nature. Molecular studies identified a clonal Vbeta3-Cbeta RT-PCR product. Both PCR heteroduplex analysis and GeneScan analysis found clonal TCRB and TCRG gene rearrangements. CONCLUSIONS: An underlying T-LGL leukemia should be investigated in the diagnostic evaluation of acquired PRCA and neutropenia in young children. Both flow cytometric and molecular analyses can be used to establish the clonal nature of T-LGL.

Child↗
PubMed2004

Detection of single nucleotide polymorphisms in the mannose-binding lectin gene using minor groove binder-DNA probes.

Structural point mutations in exon 1 at codons 52, 54 and 57 and a promotor polymorphism at -221 bp of the mannose-binding lectin (MBL) gene are associated with increased susceptibility to various infectious diseases. We developed a genotyping method based on the 5' nuclease (TaqMan) assay in combination with the use of minor-groove-binder (MGB) probes in screening for these mutations/polymorphisms. In contrast to conventional probes, MGB probes have a short length and can be used for detection of mutations that are in close proximity to each other, as is the case for the structural mutations in exon 1 of the MBL gene. Results obtained with the 5' nuclease assay using MGB probes were identical with results obtained with classical techniques such as restriction fragment length polymorphism, allele-specific PCR, and sequencing. In conclusion, the 5' nuclease assay using MGB probes is useful for large-scale screening of point mutations/polymorphisms, even when they are in close proximity.

DNA Primers↗
PubMed2004

Pancreatic autoantibodies in inflammatory bowel disease.

BACKGROUND: Autoantibodies against exocrine pancreas (PABs) have been reported to be specific for Crohn's disease (CD), albeit at a low prevalence (30%). We studied PABs in patients with inflammatory bowel disease (IBD), unaffected family members, and control subjects. METHODS: A Belgian study cohort of 575 subjects, including 289 IBD patients (CD, 169 patients; ulcerative colitis [UC], 120 patients), 108 unaffected first-degree relatives, 78 subjects with non-IBD gastrointestinal disorders (gastrointestinal control subjects [GIcos]), and 100 healthy control subjects (Hcos), were tested for PAB by a standardized indirect immunofluorescence method. RESULTS: The prevalence of PABs in this study cohort was 32% for CD, 23.3% for UC, and 22.2% for their unaffected family members (all P < 0.001), compared with 1.3% for GIcos and 0% for Hcos. Two staining patterns could be observed: an intracellular pattern (IC); and an extracellular pattern (EC). The EC was significantly more prevalent in CD patients compared with UC patients (P = 0.014), and higher titers of this pattern were found in CD patients (P = 0.01). Both PAB patterns were negatively associated with stricturing disease behavior of CD (P = 0.021). The IC was associated with familial CD (P = 0.0009) and familial UC (P = 0.0003). CONCLUSIONS: The prevalence of PAB found in CD patients in this study was similar to that cited in previous reports. In contrast to these reports, we also found an increased prevalence of PABs in patients with UC and in unaffected first-degree relatives of IBD patients. We observed two main staining patterns, both of which were present in IBD and were associated with specific phenotypes of the disease.

Adolescent↗
PubMed2003

Autoimmunity associated with anti-tumor necrosis factor alpha treatment in Crohn's disease: a prospective cohort study.

BACKGROUND & AIMS: Infliximab therapy is an effective approach to treating Crohn's disease. Development of antinuclear antibodies has been described in patients treated, but the size of the problem and the relationship with autoimmunity have not been investigated. We investigated the occurrence of antinuclear antibodies in 125 consecutive Crohn's disease patients and studied the relationship with symptoms of autoimmunity. METHODS: Autoantibodies and clinical data were investigated before and 1, 2, and 3 months after infliximab infusion. If antinuclear antibodies were > or =1:80, further study of double-stranded DNA, single-stranded DNA, histones, and ENA was performed. RESULTS: Cumulative antinuclear antibody incidence at 24 months was 71 of 125 (56.8%). Almost half of these patients developed antinuclear antibodies after the first infusion, and >75% became antinuclear antibody positive after fewer than 3 infusions. So far, only 15 of 71 patients have become seronegative, after a median of 12 months. Of 43 antinuclear antibody-positive patients who were further subtyped, 14 of 43 (32.6%) had double-stranded DNA, 17 (39.5%) had single-stranded DNA, 9 (20.9%) had antihistone, and 0% were ENA positive. Two patients (both antihistone and double-stranded DNA positive) developed drug-induced lupus without major organ damage, and 1 developed autoimmune hemolytic anemia. Antinuclear antibodies were associated with the female sex (odds ratio, 3.166; 95% confidence interval, 1.167-8.585; P = 0.024) and with papulosquamous or butterfly rash (odds ratio, 10.016; 95% confidence interval, 1.708-58.725; P = 0.011). CONCLUSIONS: The cumulative incidence of antinuclear antibodies was 56.8% after 24 months in this cohort of infliximab-treated Crohn's disease patients. Antinuclear antibodies persisted up to 1 year after the last infusion, and only a few patients became seronegative. Two patients developed drug-induced lupus erythematosus. Antinuclear antibodies were associated with the female sex and skin manifestations.

Adult↗
PubMed2003

National external quality assessment scheme for lymphocyte immunophenotyping in Belgium.

In 2000, the Belgian Scientific Institute of Public Health introduced a voluntary external quality assessment scheme for lymphocyte immunophenotyping. This paper provides an analysis of the first six surveys. Specimens consisted of fresh EDTA-anticoagulated whole blood and were sent by overnight mail. The 41 participants were surveyed for methodology and were asked to report white blood cell count, percentage of lymphocytes, and percentages and absolute numbers of CD3+, CD4+, CD8+, and CD19+ cells. Median intralaboratory coefficients of variation were 1.0, 1.3, 1.7, and 3.2% for CD3+, CD4+, CD8+, and CD19+ cell percentages, respectively. Interlaboratory variability was consistently lower than 6.5% for CD3+ and CD4+CD3+ cell percentages, and lower than 9.5% for CD8+CD3+ cell percentages. Median coefficients of variation for the absolute values were higher, ranging from 10.1% for CD4+CD3+ cells to 16.5% for CD19+ cells. The percentage of CD4+CD3+ and CD8+ CD3+ cells was in several samples significantly lower than the percentage of total CD4+ and CD8+ cells. The number of laboratories measuring total CD4+ and CD8+ cells decreased by 30% during the programme. Between-laboratory variability remained stable over time. Analysis of individual laboratory performance indicated that some laboratories markedly improved their results.

Antigens, CD↗
PubMed2003

Automated serum protein electrophoresis by Capillarys.

Capillary zone electrophoresis (CZE) of serum proteins is increasingly gaining impact in clinical laboratories. In this report, we evaluate automated capillary zone electrophoresis by Capillarys (Sebia, France). Within-run and between-run imprecision for the five electrophoretic fractions was <2% and <6%, respectively. Data obtained with Capillarys correlated with results obtained with agarose gel electrophoresis and Paragon CZE 2000 (Beckman Coulter, USA). Analysis of serum obtained from patients with inflammation, nephrotic syndrome, bisalbuminemia, and alpha1-antitrypsin deficiency revealed that Capillarys was able to detect these abnormalities. Two hundred thirty eight samples were analyzed by agarose gel electrophoresis, Capillarys, capillary electrophoresis using Paragon CZE 2000 system, and immunofixation. Sample selection was based on the presence of a disturbed morphology (e.g., spike) of the protein profile or hypogammaglobulinemia on agarose gel electrophoresis and/or Capillarys. Immunofixation revealed the presence of a monoclonal protein, oligoclonal bands, polyclonal pattern, and a normal profile in, respectively, 89, 66, 19, and 64 samples. With Capillarys, Paragon, and agarose gel electrophoresis, a spike and/or disturbed morphology of the profile was found in 222, 182, and 180 samples, respectively. In these samples, immunofixation was negative in 73 (33%), 46 (25%), and 39 (22%) samples, respectively. These data indicate that Capillarys has a lower specificity than agarose gel electrophoresis and Paragon 2000. Of the 89 samples with a monoclonal protein, Capillarys, Paragon, and agarose gel electrophoresis failed to detect, respectively, three, three, and one monoclonal protein(s). Interferences by radio-opaque agents, complement degradation products, fibrinogen, and triglycerides are described. In conclusion, automated capillary zone electrophoresis with Capillarys provides for reproducible, rapid, and reliable serum electrophoresis.

Adult↗
PubMed2003

Separation of serum proteins by automated capillary zone electrophoresis.

Capillary zone electrophoresis (CZE) of serum proteins is increasingly gaining impact in clinical laboratories. Two automated multichannel instruments dedicated to the separation of serum proteins have become available over the last 6 years, the Paragon CZE 2000 (Beckman Coulter, CA, USA) and, more recently, the Capillarys (Sebia, France). This review focuses on the performance of these commercial instruments to separate serum proteins in a clinical laboratory setting. The utility of CZE to recognize various dysproteinemias and to detect and identify monoclonal proteins will be described and systematically reviewed. The reader will be provided with a summation and an understanding of CZE-specific interference.

Blood Protein Electrophoresis↗
PubMed2002

Essential role for CD40 ligand interactions in T lymphocyte-mediated modulation of the murine immune response to pneumococcal capsular polysaccharides.

Protection against infection with pneumococci is provided by anti-capsular polysaccharide (caps-PS) Abs. We investigated whether CD40 ligand (CD40L) plays a role in T lymphocyte-mediated regulation of the immune response to caps-PS, which are considered thymus-independent Ags. Administration of MR1, an antagonist mAb against murine CD40L, in BALB/c mice immunized with Pneumovax resulted in an inhibition of the IgM and IgG Ab response for various caps-PS serotypes. Evidence for the involvement of CD4(+) T lymphocytes in the Ab response to caps-PS was obtained in SCID/SCID mice that, when reconstituted with B lymphocytes and CD4(+) T lymphocytes, mounted a higher specific IgM response compared with SCID/SCID mice reconstituted with only B lymphocytes. This helper effect of CD4(+) T lymphocytes was abrogated by MR1. Blocking CD40L in vitro decreased the IgM response to caps-PS and abolished the helper effect of CD4(+) T lymphocytes. CD8(+) T lymphocyte-depleted murine spleen cells mounted a higher in vivo immune response than total murine spleen cells, which provided evidence for a suppressive role of CD8(+) T lymphocytes on the anti-caps-PS immune response. CD4(+) T lymphocyte-depleted murine spleen cells, leaving a B and CD8(+) T lymphocyte fraction, elicited only a weak in vivo and in vitro Ab response, which was enhanced after MR1 administration. In summary, our data provide evidence that T lymphocytes contribute to the regulation of the anti-caps-PS immune response in a CD40L-dependent manner.

Animals↗
PubMed2002

The value of serologic markers in indeterminate colitis: a prospective follow-up study.

BACKGROUND & AIMS: In the absence of pathognomonic markers for Crohn's disease (CD) and ulcerative colitis (UC), the diagnosis of inflammatory bowel disease depends on a compendium of clinical, radiographic, endoscopic, and histologic criteria that bears imperfect specificity to the individual disorders. In 10% of cases of colitis, no differentiation can be made between CD and UC; these patients are diagnosed with indeterminate colitis (IC). We evaluated the value of anti-Saccharomyces cerevisiae antibodies (ASCA) and perinuclear antineutrophil cytoplasmic antibodies (pANCA) to increase diagnostic accuracy in categorizing IC. METHODS: Since 1996, 97 patients with IC from 3 centers (Leuven, Lille, and Vienna) were enrolled, analyzed for pANCA and ASCA, and followed up prospectively. RESULTS: A definitive diagnosis has been reached for 31 of 97 patients (32%). In these patients, ASCA+/pANCA- correlated with CD in 8 of 10 patients, whereas ASCA-/pANCA+ correlated with UC in 7 of 11 patients. The remaining 4 cases became CD, clinically behaving as UC-like CD. Almost half of the patients (47 of 97 [48.5%]) were negative for ASCA and pANCA, and 40 remain diagnosed with IC to date. Only 7 seronegative cases (14.9%) became CD or UC compared with 48% (24 of 50) of seropositive patients (P < 0.001). CONCLUSIONS: Results so far show that ASCA+/pANCA- predicts CD in 80% of patients with IC and ASCA-/pANCA+ predicts UC in 63.6%. Interestingly, 48.5% of patients do not show antibodies against ASCA or pANCA. Most of these patients remain diagnosed with IC during their further clinical course, perhaps reflecting a distinct clinicoserological entity.

Adolescent↗
PubMed2002

Novel nephelometric assay for measurement of complement 3d.

BACKGROUND: This report describes a nephelometric assay for measuring complement 3d (C3d). METHODS: C3d was separated from C3 and the other C3 split products by polyethylene glycol precipitation. The supernatant containing C3d was then measured by rate nephelometry in a Beckman Immage rate nephelometer using a specific antibody. Calibration was performed with dilutions of a standard, which was obtained by incubating a serum pool at 37 degrees C for 7 days. This incubation step allowed the activation and breakdown of C3 into C3d. RESULTS: The assay was linear across the normal and pathological range. Precision studies showed within-run and between-run coefficients of variation of < 5% and < 6%, respectively. The nephelometric results are comparable with those obtained by radial immunodiffusion. Neither haemoglobin nor lipids interfere with the assay.

Antigen-Antibody Reactions↗