Connective Tissue Diseases

Single Analytes 1

Autoantibodies against

dsDNA | U1RNPSm  | SS-A/Ro | SS-B/La  

 

dsDNA

Products

Article No.

No. of tests

Varelisa dsDNA Antibodies 141 96 96 tests
EliA dsDNA 14-5500-01 4x12 tests 

Promotion Material

Antigens

Deoxyribonucleic acid (DNA) as antigen may be either double-stranded (dsDNA) or single-stranded (ssDNA), but only dsDNA antibodies are specific markers. For use in anti-DNA assays, DNA from tissue, from eukaryotic cell, from bacteria or from bacteriophages is used. Circular plasmid DNA is a very suitable choice, because the risk to incorporate single strands is very low.

In the Varelisa and EliA assays the DNA is coated as recombinant plasmid double-stranded DNA.

Disease association, antibody prevalence and specificity

Systemic lupus erythematosus (SLE), dependent on method used and on the activity status of patients the antibody prevalence varies betwenn less than 30 to more than 90%.  Anti-dsDNA antibodies belong to the ARA (American Rheumatism Association) diagnostic criteria for SLE.

Information about SLE

The disease specificity varies highly, dependent on the method used. With highly sensitive methods, anti-dsDNA can be found in uveitis, discoid lupus erythematosus, rheumatoid arthritis, juvenile rheumatoid arthritis and further in a wide variety of patients. In these cases, we are mostly dealing with antibodies of the IgM isotype of IgG with low avidity.  

Disease activity

Good correlation of anti-dsDNA titer and disease activity, thus important for monitoring, especially high aviditiy IgG antibodies. A rise of the antibody titer can predict an exacerbation of the disease. Quantitative anti-dsDNA IgG should be measured regularly in SLE patients.

When is the measurement recommended?

Suspicion of SLE, monitoring of SLE.

Antibody isotypes

IgG. IgM is often determined, but the clinical significance in diagnosis and monitoring is reduced.

Detection methods

IIf on Crithidia luciliae (CLIFT), radiobinding assays (mainly Farr assay) and enzyme-linked immunosorbent assays (ELISA).

References

  • Hochberg MC (1997) Updating the American College of Rheumatology Revised Criteria for the Classification of Systemic Lupus Erythematosus. Arthr Rheum 40, 1725-1734
  • Bootsma H, Spronk PE, Ter Borg EJ et al. (1997) The predictive value of fluctuations in IgM and IgG class anti-dsDNA antibodies for relapses in systemic lupus erythematosus. A prospective long term observation. Ann Rheum Dis 56, 661-666 
  • Tzioufas AG, Tergoglou C, Stavropoulos ED et al. (1990) Determination of anti-dsDNA antibodies by three different methods: Comparison of sensitivity, specificity and correlation with lupus acticity index (LAI). Clin Rheumatol 9, 186-192

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 U1RNP

Products

Article No.

No. of tests

Varelisa RNP Antibodies 170 96 96 tests
Varelisa RNP-Sm Antibodies 165 96 96 tests
EliA U1RNP 14-5501-01 4x12 tests
EliA RNP70 14-5511-01 4x12 tests

Promotion Material

Performance Folder
EliA ENA (extractable nuclear antigens) (pdf)
Sm, U1RNP, RNP70, Ro, La, Scl-70, CENP, Jo-1

Antigens

In their natural state, the small nuclear RNAs, also called U-RNAs (for "uracil rich RNAs"), exist as ribonucleoprotein particles (snRNP). The U1 snRNA is present as complex with the Sm proteins, which are found also in the U2, U4 and U5 snRNPs, and the U1-specific proteins 70 kDa, A (34 kDa) and C (22 kDa).

U1 snRNP complexes are primarily localized in the nucleoplasm and are involved in the splicing process.

The Varelisa RNP Antibodies assay and the EliA U1RNP and RNP Wells use human recombinant U1 snRNP proteins. The Varelisa RNP-Sm Antibodies assay contains the purified complex.

Disease association, antibody prevalence and specificity

  • Systemic lupus erythematosus (SLE) (30-40%) anti-RNP may occur alone but often present in conjunction with other specificities. Anti-Sm positive sera are almost always also positive for anti-RNP.
  • Mixed connective tissue disease (MCTD) is defined by the presence of high titer anti-RNP (especially anti-70 kDa antibodies, but also anti-A and -C).
  • Anti-U1 RNP antibodies may also occur in a small fraction of patients with Sjögren's syndrome, rheumatoid arthritis, scleroderma, and polymyositis.

Disease activity

Longitudinal studies have indicated that anti-U1 RNP antibody titers vary over time, but it is uncertain whether these levels reflect underlying disease activity.

When is the measurement recommended?

Suspicion of SLE or MCTD.

Antibody isotype

IgG

Other detection methods

IIF on HEp-2 (coarse speckled pattern). The immunofluorescence technique cannot distinguish between anti-U1 snRNP and anti-Sm antibodies. Other techniques (immunodiffusion, immunoblotting, RNA immunoprecipitation etc.) are possible but not necessarily useful for routine.

References

  • Van den Hoogen FHJ, Van de Putte LBA (1996) ANti-U1snRNP antibodies and clinical associations. In: Van Venrooij WJ, Maini RN (eds.) Manual of Biological Markers of Disease, Kluwer Academic Publishers, Amsterdam 
  • Craft J, Hardin J (1992) Anti-snRNP antibodies. In: Wallace DJ, Hahn BH (eds.), Dubois' Lupus Erythematosus, pp 216-219, Williams and Wilkens 
  • Peng SL, Craft JE (1996) Spliceosomal snRNPs autoantibodies. In: Peter JB, Shoenfeld Y (eds.), Autoantibodies, pp 774-782, Elsevier Science B.V., Amsterdam

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Sm

Products

Article No.

No. of tests

Varelisa Sm Antibodies 182 96 96 tests
EliA Sm 14-5502-01 4x12 tests

Promotion Material

Performance Folder
EliA ENA (extractable nuclear antigens) (pdf)
Sm, U1RNP, RNP70, Ro, La, Scl-70, CENP, Jo-1

Antigens

In their natural state, the small nuclear RNAs, also called U-RNAs (for "uracil rich RNAs"), exist as ribonucleoprotein particles (snRNP). The U snRNP U1, U2, U4, U5 and U6 all contain a group of proteins, the so-called Sm peptides, with the major targets being the B and D polypeptides. Because of cross-reactivity between the A, the C and the B/B' proteins, up to 60% of anti-U1 RNP sera may react with B/B'. Thus, only the presence of anti-D and/or the absence of anti-A and anti-C can be regarded as characteristic for an anti-Sm sera. Until now, all attempts to produce an antigenic recombinant SmD protein with a good reactivity failed because of its very special structure.

EliA Sm Well is coated with a purified Sm antigen. Varelisa Sm Antibodies assay is coated with SmD peptide.

Disease association, antibody prevalence and specificity

Systemic lupus erythematosus (SLE) (10-20% in caucasian SLE patients), Sm antibodies are highly specific, but relatively insensitive marker for SLE. Their presence constitutes one of the revised ARA criteria for diagnosis.

Information about SLE

Anti-Sm positive sera are almost always also positive for anti-RNP.

Anti-Sm reactivity is not described definitely in other diseases, although a few studies describe Sm antibodies in monoclonal gammopathies, schizophrenia and uveitis.

Disease activity

Numerous studies suggest the association of anti-Sm antibodies with disease activity and particular disease manifestations.

When is the measurement recommended?

Suspicion of SLE.

Antibody isotype

IgG

Other detection methods

IIF on HEp-2 (punctate staining pattern throughout the nucleus; only the nucleolar regions are generally unstained). The immunofluorescence technique cannot distinguish between anti-U1 snRNP and anti-Sm antibodies. Other methods (e.g. counterimmunoelectrophoresis, immunoprecipitation; immunoblotting) can be used but are not necessarily useful for routine.

References

  • Mahler M, Fritzler MJ, Blüthner M (2004) Identification of a SmD3 epitope with a single symmetrical dimethylation of an arginine residue as a specific target of a subpopulation of anti-Sm antibodies. Available online http://arthritis-research.com/content/7/1/R19
  • Peng SL, Craft JE (1996) Spliceosomal snRNPs autoantibodies. In: Peter JB, Shoenfeld Y (eds.), Autoantibodies, pp 774-782, Elsevier Science B.V., Amsterdam 
  • Hoch SO (1994) Autoantigens in SLE - Sm. In: Van Venrooij WJ, Maini RN (eds.) Manual of Biological Markers of Disease, Kluwer Academic Publishers, Amsterdam 
  • Craft J, Hardin J (1992) Anti-snRNP Antibodies. In: Wallace DJ, Hahn BH (eds.) Dubois' Lupus erythematosus. Lippincott Williams & Wilkins

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SS-A/Ro

Products

Article No.

No. of tests

Varelisa SS-A/Ro Antibodies 166 96 96 tests
EliA Ro52 NEW! 14-5598-01 2x12 tests
EliA Ro60 NEW! 14-5525-01 4x12 tests
EliA Ro 14-5503-01 4x12 tests

Promotion Material

Performance Folder
EliA ENA (extractable nuclear antigens) (pdf)
Sm, U1RNP, RNP70, RO, La, Scl-70, CENP, Jo-1

Antigens

The SS-A/Ro particle contains a hY RNA (human cytoplasmic RNA) and associated proteins: a 60 kDa and a 52 kDa protein. The 52 kDa protein is not directly bound to the hY RNA but to the 60 kDa protein. It seems that it is sometimes associated, sometimes not. The Ro antigen is found in the cytoplasm but also in the nucleus. The role of the SS-A/Ro particle in the cell is not known yet.

Phadia assays use human recombinant Ro 60 and Ro 52.

Disease association, antibody prevalence and specificity

  • Primary Sjögren's syndrome (60-75%), part of the diagnostic criteria 
  • Secondary Sjögren's syndrome (about 80%) 
  • Systemic lupus erythematosus, SLE (40-50%) 
  • Mothers of children with neonatal lupus syndrome (100%), but only one in 50 children born to mothers with anti-Ro develop heart block. 
  • Rheumatoid arthritis (2-10%) 
  • Other autoimmune diseases (rarely, with sensitive methods) 
  • Normal controls (0.5%)

Anti-Ro 52 kDa are frequently found in Sjögren's syndrome, whereas anti-Ro 60 kDa are observed more often in SLE.

Information about Sjögren's Syndrome

Disease activity

Anti-Ro are reflecting the extension of the disease in Sjögren's syndrome and are associated in particular with the extraglandular manifestations and serologic findings of the syndrome. On the other hand, anti-Ro levels do not noticeably fluctuate with disease activity or with steroids and/or immunotherapy.

In SLE patients Ro60, Ro52 and La antibody profile is fixed at an early stage of disease and in most patients hardly changes.

When is the measurement recommended?

  • Suspicion of primary Sjögren's syndrome
  • Skin involvement compatible with subacute cutaneous lupus erythematosus
  • Rheumatoid arthritis, prior to D-penicillamine administration
  • Women with Sjögren's syndrome, SLE or rheumatoid arthritis before and during pregnancy

Antibody isotype

IgG

References

  • Reichlin M, Scofield RH (1996) SS-A (Ro) Autoantibodies. In: Peter JB, Shoenfeld Y (eds.), Autoantibodies, pp 783-788, Elsevier Science B.V., Amsterdam 
  • Mavragani CP, Tzioufas AG, Moutsopoulos HM (2000) Sjögren's syndrome: Autoantibodies to cellular antigens - Clinical and molecular aspects. Int Arch Allergy Immunol 123, 46-57 
  • Scofield RH, Farris AD, Horsfall AC, Harley JB (1999) Fine specificity of the autoimmune response to the Ro/SSA and La/SSB ribonucleoproteins. Arthritis Rheum 42, 199-209

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SS-B/La  

Products

Article No.

No. of tests

Varelisa SS-B/La Antibodies 166 96 96 tests
EliA La 14-5504-01 4x12 tests

Promotion Material

Performance Folder
EliA ENA (extractable nuclear antigens) (pdf)
Sm, U1RNP, RNP70, RO, La, Scl-70, CENP, Jo-1

Antigens

The La/SS-B is a ubiquitously expressed phosphoprotein with 47 kDa, that associates with a variety of small RNAs including the hY RNA of the SS-A/Ro particle. La probably is a transcription termination factor for RNA polymerase III and is found in the cytoplasm as well as in the nucleus.

Phadia assays utilize human, recombinant La.

Disease association, antibody prevalence and specificity

  • Primary Sjögren's syndrome (up to 90%), diagnostic criterion
  • Secondary Sjögren's syndrome (about 50%)
  • Systemic lupus erythematosus, SLE (6-15%)
  • Subacute cutaneous lupus erythematosus (25-35%)
  • Mothers of children with neonatal lupus syndrome (90%)

Information about Sjögren's Syndrome

Anti-La are almost always associated with anti-Ro and particularly the 52 kDa component.

Disease activity

Whether the titer of anti-La correlates with disease activity in Sjögren's syndrome or SLE is unknown. Detection of anti-La antibodies is a meaningful serological finding. Concentrations of anti-La antibodies do not fluctuate during the course of disease.

When is the measurement recommended?

  • Suspicion of primary Sjögren's syndrome
  • Skin involvement compatible with subacute cutaneous lupus erythematosus
  • Rheumatoid arthritis, prior to D-penicillamine administration
  • Women with Sjögren's syndrome, SLE or rheumatoid arthritis before and during pregnancy

Antibody isotypes

IgG

References

  • Keech CL, McCluskey J, Gordon TP (1996) SS-B (La) Autoantibodies. In: Peter JB, Shoenfeld Y (eds.), Autoantibodies, pp 789-797, Elsevier Science B.V., Amsterdam 
  • Mavragani CP, Tzioufas AG, Moutsopoulos HM (2000) Sjögren's syndrome: Autoantibodies to cellular antigens - Clinical and molecular aspects. Int Arch Allergy Immunol 123: 46-57 
  • Scofield RH, Farris AD, Horsfall AC, Harley JB (1999) Fine specificity of the autoimmune response to the Ro/SSA and La/SSB ribonucleoproteins. Arthritis Rheum 42: 199-209

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