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J F Meilof

Publications and source records attributed to J F Meilof.

29 records · Page 2Linked to original sources
PubMed1992

The development of a quantitative assay for the detection of anti-Ro/SS-A and anti-LA/SS-B autoantibodies using purified recombinant proteins.

A characteristic of patients with autoimmune diseases such as Sjögren's syndrome and systemic lupus erythematosus is the presence of anti-Ro/SS-A and anti-La/SS-B autoantibodies in their circulation. In order to investigate specific autoantibody levels in the sera of these patients quantitative assays for the detection of both anti-Ro/SS-A and anti-La/SS-B reactivity were developed. Ro/SS-A (60 kDa) and La-SS-B (50 kDa) cDNAs were cloned and expressed in E. coli as non-fusion proteins. These were purified to homogeneity using two different purification protocols. With these recombinant antigens, specific enzyme-linked immunosorbent assays (ELISAs) were developed. 40 sera positive for anti-Ro/SS-A autoantibodies in counterimmunoelectrophoresis (CIE) were tested in both the Ro/SS-A and La/SS-B ELISA. Activity values reproducibly ranged from 1536 to 120,000 U in the Ro/SS-A ELISA and from 763 to 2,500,000 U in the La/SS-B ELISA. The suitability of these ELISAs as screening assays was further investigated by testing 200 sera sent to our laboratory for routine detection of autoantibodies to extractable nuclear antigen (ENA: anti-Sm, anti-RNP, anti-Ro/SS-A and anti-La/SS-B). Both ELISAs showed a high sensitivity and specificity (Ro/SS-A ELISA 85% and 94%, La/SS-B ELISA 100% and 98% respectively), when compared to the standard assays, the RNA-precipitation assay and the HeLa immunoblotting test. From these data we conclude that a quantitative analysis of both anti-Ro/SS-A and anti-La/SS-B autoantibodies is now possible using purified recombinant non-fusion proteins. For screening purposes the La/SS-B ELISA showed a great improvement in sensitivity for the detection of anti-La/SS-B activity in comparison to the La/SS-B CIE, while the Ro/SS-A ELISA almost equalled the performance of the Ro/SS-A CIE.

Autoantibodies↗
PubMed1992

Anti-Ro/SS-A and anti-La/SS-B autoantibody levels in relation to systemic lupus erythematosus disease activity and congenital heart block. A longitudinal study comprising two consecutive pregnancies in a patient with systemic lupus erythematosus.

OBJECTIVE: To analyze the anti-Ro/SS-A and anti-La/SS-B autoantibody responses, both quantitatively and qualitatively, in relation to the occurrence of congenital heart block (CHB) and disease activity in a patient with systemic lupus erythematosus. METHODS: The patient's course was carefully documented for a period of 80 months. Specific enzyme-linked immunosorbent assays, a HeLa cell immunoblotting test, and an RNA precipitation assay were used to determine autoantibody levels and fine specificities. RESULTS: Anti-Ro/SS-A and anti-La/SS-B antibody did not disappear. Levels of anti-Ro/SS-A appeared to fluctuate more frequently than levels of anti-La/SS-B. Fluctuations were unrelated to disease activity or immunosuppressive treatment. There was no characteristic relationship between levels of these antibodies and the occurrence of CHB. CONCLUSION: The occurrence of CHB cannot be predicted by frequent measurement of anti-Ro/SS-A and anti-La/SS-B levels. The immunoregulatory control of anti-Ro/SS-A and anti-La/SS-B antibodies differs from that of anti-DNA and anti-tetanus toxoid antibodies.

Adult↗
PubMed1992

Analysis of heavy and light chain use of lupus-associated anti-La/SS-B and anti-Sm autoantibodies reveals two distinct underlying immunoregulatory mechanisms.

The immunoregulatory mechanisms involved in autoimmune diseases are still unclear. One approach to elucidating these mechanisms involves evaluation of the clonality of the lymphocytes involved in autoimmunity. Molecular analysis of the rearrangement patterns of antigen receptor genes in T cells and B cells has produced ambiguous results. The present study focuses on the analysis of the autoantibodies themselves, being the end products of autoimmune reactivity. Heavy and light chain use of autoantibodies and of total IgG was determined in sera containing anti-La/SS-B and/or anti-Sm antibodies, two autoantibody specificities associated with rheumatic diseases such as systemic lupus erythematosus and Sjögren's syndrome. From our experiments, the anti-La/SS-B response emerges as an oligoclonal, IgG1-restricted B-cell response associated with sharply elevated levels of total serum IgG1-kappa. These characteristics are in sharp contrast to the polyclonal, IgG-subclass-unrestricted anti-Sm response which is accompanied by normal or slightly elevated total serum IgG levels. These findings suggest that anti-La/SS-B autoantibodies, in contrast to anti-Sm autoantibodies, are the product of a restricted oligoclonal B-cell response and thus may be the consequence of a (virally triggered) benign B-cell lymphoma.

Autoantibodies↗
PubMed1992

Autoantibodies and their target antigens in Sjögren's syndrome.

The subject of this review is the humoral autoimmune response in Sjögren's syndrome. Autoantibodies in this disease are primarily directed against the Ro/SS-A and La/SS-B autoantigens and against IgG (rheumatoid factor). The Ro/SS-A and La/SS-B autoantigens consist of a number of antigenic proteins coupled to small RNA molecules. These RNA-protein particles are present in all human cells and are strongly conserved throughout various species. Anti-Ro/SS-A and anti-La/SS-B autoantibodies can be detected using counter-immunoelectrophoresis, immunoblotting technique, ELISA or RNA precipitation assays. The preferred method of screening for anti-Ro/SS-A antibodies in human sera is counter-immunoelectrophoresis; anti-La/SS-B antibodies are best detected with the immunoblotting technique. Anti-Ro/SS-A antibodies are found in 60% of patients with Sjögren's syndrome, but are not specific markers for this disease. Anti-La/SS-B antibodies are present in approximately 40% of patients with Sjögren's syndrome; the only other disease where the antibody has been detected is systemic lupus erythematosus (15% positive). The origin and possible pathogenetic role of autoantibodies in Sjögren's syndrome is still unclear. Our view is that the current evidence supports a mechanism whereby autoantibodies are the product of an oligoclonal B-cell proliferation. The only instance where autoantibodies probably play a direct pathogenetic role is the occurrence of congenital heart block in the offspring of anti-Ro/SS-A and anti-La/SS-B positive mothers.

Autoantibodies↗
PubMed1991

Characterization of the autoantigen calreticulin.

Anti-Ro/SS-A antibodies are commonly found in the sera of patients with Sjögren's syndrome and SLE. These antibodies also occur in the mothers of children with neonatal lupus and congenital heart block. Ro/SS-A is a ribonucleoprotein complex whose cellular function remains unknown. To study its cellular function and to characterize its immunoreactivity, we have used an oligonucleotide designed after the published amino terminal sequence of a putative 60-kDa Ro/SS-A autoantigen to isolate its cDNA. This cDNA encodes a polypeptide that is the human homologue of calreticulin, a calcium binding protein of the endoplasmatic reticulum. The encoded polypeptide also shows a 64.4% identity with RAL-1, an Ag of the river blindness pathogen Onchocerca volvulus. Contrary to the data published by other authors, our results indicate that calreticulin is not a Ro/SS-A autoantigen. Moreover, we show that anticalreticulin autoantibodies occur in the sera of patients with SLE and patients with onchocerciasis.

Amino Acid Sequence↗
PubMed1991

Prevalence of antiphospholipid antibodies in patients with fetal loss.

The prevalence of antiphospholipid and antinuclear antibodies in 102 patients with at least three unexplained miscarriages before a gestational age of 12 weeks, or at least one intrauterine fetal death after 12 weeks, was investigated and compared with the prevalence in 102 normal pregnant controls. Six patients had a history of thrombosis and six had 'lupus-like' disease. Twenty one patients had anticardiolipin antibodies compared with 10 controls. Serum samples of nine patients and one control contained antinuclear antibodies. The lupus anticoagulant was present in the plasma of five patients with anticardiolipin antibodies. The influence of patient selection on the results was illustrated by the finding that antiphospholipid antibodies and antinuclear antibodies were mainly detected in patients with lupus-like disease or a history of thrombosis. When these patients were excluded there was no significant difference in the prevalence of anticardiolipin and antinuclear antibodies between patients and controls. Therefore, in the absence of lupus-like disease or a history of thrombosis, screening for antiphospholipid antibodies in patients with adverse pregnancy outcomes seems not to be indicated.

Abortion, Habitual↗
PubMed1990

The detection of anti-Ro/SS-A and anti-La/SS-B antibodies. A comparison of counterimmunoelectrophoresis with immunoblot, ELISA, and RNA-precipitation assays.

The presence in serum of anti-Ro/SS-A and/or anti-La/SS-B autoantibodies is a characteristic of autoimmune diseases such as Sjögren's syndrome and systemic lupus erythematosus. To evaluate different assays currently available for the detection of these antibodies 50 sera were tested using the four different assay methods: counterimmunoelectrophoresis (CIE), RNA precipitation assay, immunoblotting technique and ELISA. The RNA-precipitation assay showed the highest sensitivity and specificity. The CIE for the detection of anti-Ro/SS-A antibodies gave comparable results whereas the Ro/SS-A ELISA and Ro/SS-A or HeLa immunoblot showed lower sensitivities (96% and 80% respectively). Sensitivity was even lower (66%) when only reactivity towards the 60 kDa Ro/SS-A protein was considered. The ELISA for the detection of anti-La/SS-B antibodies showed a sensitivity of 98%, the immunoblotting technique of 86% and the CIE only 67%. The high sensitivity of the La/SS-B ELISA went together with a low specificity of 14%. We conclude from these data that for the detection of anti-Ro/SS-A and anti-La/SS-B antibodies the RNA precipitation assay shows the highest sensitivity and highest specificity. For routine screening purposes the CIE is the most convenient and reliable assay to detect anti-Ro/SS-A antibodies. For the detection of anti-La/SS-B antibodies the immunoblot corresponds most closely to the RNA precipitation assay.

Antibodies, Antinuclear↗
PubMed1990

Fine specificities of anti-nuclear antibodies in murine models of graft-versus-host disease.

Two models of murine graft-versus-host disease (GVHD) were studied with respect to autoantibody production and development of systemic lupus erythematosus (SLE) like disease. One model was induced by injection of (B10.A(4R) x B10.A(2R]F1 mice with parental (B10.A(4R] spleen and lymph node cells (groups I GVHD), the other by injection of (DBA/2 x C57/B16)F1 mice with DBA/2 cells (group II GVHD). Group I GVHD mice remained in a seemingly healthy condition and did not show any proteinuria, in spite of high titres of anti-nuclear antibodies including antibodies to dsDNA, anti-Sm and anti-ribosomal P protein antibodies. Measured levels of these autoantibodies as well as their isotypes were comparable with those found in MRL/lpr and NZB/W mice. Group II GVHD mice developed SLE-like disease signs, including severe proteinuria. At 4 months after induction of the GVHD, almost 50% of these mice had died. At the time nephritis was present, group II mice also produced anti-dsDNA and anti-nuclear antibodies of other (unknown) specificities, but no anti-Sm or anti-P. Furthermore, the incidence of these antibodies was lower than observed in group I GVHD, MRL/lpr or NZB/W mice. It is concluded that (high avidity) anti-dsDNA as well as anti-Sm and anti-P may be present in the circulation without giving rise to the development of nephritis.

Animals↗