Transglutaminase and coeliac disease: endomysial reactivity and small bowel expression.
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This study was aimed at verifying whether tissue transglutaminase (tTG) is the sole autoantigen eliciting anti-endomysial antibodies in coeliac disease (CoD) and investigating tTG expression in normal and coeliac mucosa. Twelve anti-endomysial-positive coeliac sera and 12 anti-endomysial-negative control sera (10 microl, diluted 1:5-1:400 in PBS pH 7.3) were preincubated with 10, 20 or 50 microg guinea pig liver tTG at 4 degrees C overnight. Monkey oesophagus tissue slides were then tested with tTG-preincubated and non-preincubated sera to search for IgA anti-endomysial reactivity by indirect immunofluorescence. Moreover, six sections of monkey oesophagus were incubated with an anti-tTG mouse MoAb, six sections with an anti-cytokeratin mouse MoAb and six sections with only 3% bovine serum albumin. Finally, endoscopic duodenal biopsy sections obtained from 12 patients affected by untreated CoD, six patients affected by treated CoD and 10 biopsied controls were immunohistochemically stained with a peroxidase-conjugated anti-tTG MoAb. Our results show that (i) preincubation with tTG abolished endomysial immunofluorescence in most, but not in all, coeliac sera; (ii) the incubation of anti-tTG MoAb with sections of monkey oesophagus resulted in an immunofluorescence staining pattern similar but not identical to that of anti-endomysial-positive coeliac sera; (iii) although tTG expression was present at muscularis mucosae and pericryptal fibroblast in both normal and coeliac mucosa, it was slightly more marked and evident in the latter. Although our absorption experiment was performed with guinea pig liver tTG, we confirm that tTG is the predominant antigen of endomysial antibodies, but we speculate that, at least in some patients, it is not the only one. (+info)
Effect of plasmapheresis on ligand binding capacity and expression of erythrocyte complement receptor type 1 (CR1) of patients with systemic lupus erythematosus (SLE).
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The functional activity and the expression of CR1 on the erythrocytes (E) of patients with SLE were, respectively, determined by measuring the binding to E of either complement-opsonized bovine serum albumin (BSA)-anti-BSA immune complexes (ICC) or specific anti-ECR1 MoAbs. We found that both the functional activity and levels of ECR1 in SLE patients homozygous for ECR1 high density allele were significantly lowered compared with healthy controls having the same allele. Soon after plasmapheresis there was a significant increase in E ICC binding activity, and this increased functional activity was stable. Moreover, plasmapheresis reduced the level of immune complexes demonstrable in the circulation of the patients. The expression of ECR1 determined with several different anti-CR1 MoAbs was also elevated as a consequence of plasmapheresis. This elevation was observed for both MoAb 1B4, which competes for the ICC binding site of ECR1, and for MoAb HB8592, which does not, but the time course for the increase in binding of the two MoAbs was different, in that the epitope recognized by MoAb 1B4 increased more rapidly. The present results, considered in the context of previous findings, suggest that more than one mechanism may be operative with respect to the effects of the plasmapheresis in increasing ECR1 levels defined by different epitopes on the molecule. (+info)
Oligo-monoclonal immunoglobulins frequently develop during concurrent cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections in patients after renal transplantation.
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In the present study we report that the appearance of oligo-monoclonal immunoglobulins (oligoM-Igs) in the sera of transplanted individuals is concurrent with the detection of coincident active CMV infection and EBV replication. Eighty-four renal allograft patients were monitored with respect to CMV isolation, to CMV conventional serology and humoral response against the EBV trans-activator ZEBRA (an immediate-early antigen also called BZLF1). Titration of anti-ZEBRA antibodies (IgG and IgM) and amount of EBV DNA in serum were evaluated. Using the combination of four techniques (agarose gel electrophoresis, analytical isoelectric focusing, high resolution immunoelectrophoresis, immunofixation electrophoresis), oligoM-Igs were found in 25% of patients after allografting and significantly associated with rejection episodes (P < 0.001). Twenty out of 23 (86%) concurrent CMV/EBV infections were associated with serum oligoM-Igs (P < 0.001). One can thus reasonably assume that a sustained EBV replication following iatrogenic immunosuppression can promote the immunoglobulin heavy chain expression in EBV-infected B lymphocytes. The proliferation of immunoglobulin-secreting clones might occur after active CMV infection, through a transient over-immunosuppression or via immune subversion. (+info)
Dengue seroconversion among Israeli travelers to tropical countries.
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We tested for dengue seroconversion among 104 Israeli young adults who traveled to tropical countries for at least 3 months. Seven (6. 7%) seroconverted during travel; four (3.8%) had immunoglobulin (Ig) M antibodies; one was symptomatic with borderline IgM and a rise in IgG; two others (1.9%) had a rise in IgG titers, without detectable IgM. All four IgM-positive patients had traveled to Southeast Asia. (+info)
The past and present role of the Sabin-Feldman dye test in the serodiagnosis of toxoplasmosis.
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The dye test for the detection of Toxoplasma-specific antibodies was first described by Sabin and Feldman 50 years ago. The test is highly specific and sensitive and considerable information is available on the development and persistence of dye test antibodies after primary Toxoplasma infection. However, the test uses live Toxoplasma gondii and is now only employed in a few laboratories. It is still the reference method for the serodiagnosis of toxoplasmosis, and a multicentre study comparing dye test results between different laboratories was much needed. We report in this article the results of a multicentre evaluation of the test involving nineteen laboratories in eight countries. The study revealed overall satisfactory standardization between the laboratories, but there were differences in the test protocols, the use of reference/standard preparations and the interpretation of results. There is still no agreement on the level of dye test values which reflect infection with the parasite, and conversion from titres to international units (IUs) did not improve standardization. However, the results indicated that a value of > 4 IU or a titre of 1:16 met the definition of positivity of most participants. We recommend that the dye test be retained as a reference method and that interlaboratory standardization be improved by the use of a common protocol and the expression of results in titres. (+info)
Molecular cloning and characterization of the 120-kilodalton protein gene of Ehrlichia canis and application of the recombinant 120-kilodalton protein for serodiagnosis of canine ehrlichiosis.
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The 120-kDa outer membrane protein (p120) is a potential adhesin of Ehrlichia chaffeensis, and recombinant p120 is very useful for serodiagnosis of human monocytotropic ehrlichiosis. The analogous gene of p120 in Ehrlichia canis was cloned, sequenced, and expressed. Like the E. chaffeensis p120, the E. canis p120 contains tandem repeat units. However, neither the repeat number nor the amino acid sequences in the repeats are identical in the two Ehrlichia species. The repeat units are hydrophilic and by probability analysis are predicted to be surface exposed in both species. The repeat regions of the p120s of the two species have common amino acid sequences that are predicted to be surface exposed. The overall amino acid sequence of the E. canis p120 is 30% homologous to that of E. chaffeensis p120. Protein immunoblotting demonstrated that the recombinant E. canis p120 reacted with convalescent sera from dogs with canine ehrlichiosis. These results indicate that the recombinant p120 is a potential antigen for the serodiagnosis of canine ehrlichiosis. (+info)
Serological detection of Capillaria hepatica by indirect immunofluorescence assay.
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In this paper, a serological assay for the detection of antibodies to Capillaria hepatica, a zoonotic parasite, is described. In the past, the only way of detecting Capillaria hepatica was to perform a liver biopsy. The indirect immunofluorescence (IIF) assay, based on liver sections of naturally infected mice and human serum samples, is suitable for detecting early stages of human infections and for screening purposes. No cross-reactivity with other parasitic infections was detected. We have applied the IIF assay to serum samples of 60 employees of the Zoological Garden of Vienna, Schonbrunn, Austria, and found one positive and one questionable sample. (+info)
Overdiagnosis and overtreatment of Lyme neuroborreliosis are preventable.
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The problems of diagnosis and treatment of Lyme neuroborreliosis can be minimised by strictly following the clinical diagnostic criteria, and understanding the pitfalls of laboratory tests. The diagnosis is based solely on objective clinical findings, with serologic test results used only to confirm the diagnosis. It must be underscored that serologic testing, when ordered without regard for clinical presentation (i.e., used as a screen), may be misleading due to its extremely low positive predictive value. Enzyme-linked immunosorbent assay should always be confirmed by Western blot. The cerebrospinal fluid Borrelia burgdorferi antibody index is more meaningful than simple titres of specific antibody. Polymerase chain reaction is still a research tool and should not be utilised without clinical correlation. All serologic tests and polymerase chain reaction may remain positive long after successful treatment. Overdiagnosis and overtreatment can be minimised by following these guidelines. (+info)