Connective Tissue Diseases

Single Analytes 1

Most common markers for systemic lupus erythematosus (SLE), mixed connective tissue diseases (MCTD), Sjögren's syndrome (SS)

dsDNA | U1RNPSm  | SS-A/Ro | SS-B/La | Rib-P | Mi-2  NEW! | Fibrillarin  NEW!

 

dsDNA

Products

Article No.

No. of tests

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

Promotion material

Product folder 
EliA dsDNA (pdf)

Antigens

Deoxyribonucleic acid (DNA) as an antigen may be either double- (dsDNA) or single-stranded (ssDNA), but only dsDNA antibodies are specific markers. DNA from tissue, eukaryotic cells, bacteria or bacteriophages is used in anti-DNA assays. Circular plasmid DNA is an ideal choice, because the risk of incorporating 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), depending on method used and on the activity status of patients, antibody prevalence varies between less than 30% and more than 90%.  Anti-dsDNA antibodies are included in the ARA diagnostic criteria for SLE.

Information about SLE

The disease specificity varies highly, depending 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. These cases mostly involve antibodies of the IgM isotype of IgG with low avidity.  

Disease activity

Good correlation between anti-dsDNA titre and disease activity, thus important for monitoring, especially high-avidity IgG antibodies. An increased antibody titre 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)  |  Bootsma H, Spronk PE, Ter Borg EJ et al. (1997)  |  Tzioufas AG, Tergoglou C, Stavropoulos ED et al. (1990)

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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 ANA Differentiation (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 a complex with the Sm proteins, which are also found 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

  • Anti-RNP may occur in 30-40% of patients with systemic lupus erythematosus (SLE). The SLE sera may be monospecific for anti-RNP, but usually this antibody appears in conjunction with other antibody specificities. Anti-Sm positive sera are also almost always positive for anti-RNP.
  • Mixed connective tissue disease (MCTD) is defined by the presence of high-titre 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 or polymyositis.

Disease activity

Longitudinal studies have indicated that anti-U1 RNP antibody titres 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 anti-U1 snRNP from 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)  |  Craft J, Hardin J (1992)  |  Peng SL, Craft JE (1996)

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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 ANA Differentiation (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 of anti-Sm sera. Until now, all attempts to produce an antigenic recombinant SmD protein with good reactivity have failed because of its very special structure. In 2004, an ELISA using a dimethylated SmD peptide was developed that proved to have significantly higher specificity than that of traditional assays with purified SmD.

The 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 anti-U1 snRNP from 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)  |  Peng SL, Craft JE (1996)  |  Hoch SO (1994)  |  Craft J, Hardin J (1992)

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SS-A/Ro

Products

Article No.

No. of tests

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

Promotion material

Performance folder
EliA ANA Differentiation (pdf)
Sm, U1RNP, RNP70, RO, La, Scl-70, CENP, Jo-1

Antigens

The SS-A/Ro particle contains an hY RNA (human cytoplasmic RNA) and associated 60 kDa and 52 kDa proteins. The 52 kDa protein is directly bound to the 60 kDa protein but not to the hY RNA. The 52 kDa protein sometimes seems to be associated with the SS-A/Ro particle, 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 yet known.

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

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

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)  |  Mavragani CP, Tzioufas AG, Moutsopoulos HM (2000)  |  Scofield RH, Farris AD, Horsfall AC, Harley JB (1999)

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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 ANA Differentiation (pdf)
Sm, U1RNP, RNP70, RO, La, Scl-70, CENP, Jo-1

Antigens

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

Our assays use 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 is almost always associated with anti-Ro and particularly the 52 kDa component.

Disease activity

It is not known whether the titre of anti-La correlates with disease activity in Sjögren's syndrome or SLE. Detection per se of anti-La precipitins is a stable serological finding that does not fluctuate during the course of the 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)  |  Mavragani CP, Tzioufas AG, Moutsopoulos HM (2000)  |  Scofield RH, Farris AD, Horsfall AC, Harley JB (1999)

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Ribosomal P

Product

Article No.

No. of tests

EliA Rib-P 14-5521-01 2x12 tests

Antigen

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by multiple organ involvement resulting in disability and increased mortality. Antibodies against ribosomal-P (anti Rib-P) react against acidic phosphorylated ribosomal proteins P0, P1, and P2 (with molecular mass 38, 19, and 17 kDa, respectively) and are located on the S60 subunit of ribosomes. Anti Rib-P can be detected in approx. 15-20% of patients with SLE. They appear highly specific for SLE; they can therefore be used as a diagnostic marker for the disease. Furthermore, association has been described with particular manifestations of lupus, especially with neuropsychiatric, renal and hepatic involvements. However, results are conflicting regarding the existence of such associations, depending on differences in study set-ups, study populations or the sensitivities of tests used for the detection of anti Rib-P.

The EliA Rib-P wells are coated with human recombinant ribosomal P-proteins (P0, P1, P2).

When is the measurement recommended?

Suspicion of SLE.

Antibody isotypes

IgG

Detection methods

EliA on Phadia Laboratory Instruments

References

Kiss E, Shoenfeld Y.  |  Gerli L, Caponi L.  |  Mahler M et al.

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Mi-2   NEW!

Product

Article No.

No. of tests

EliA Mi-2 14-5604-01 2x12 tests

Promotion material

Performance folder
EliA Mi-2 (pdf)

Antigen 

There are two very similar (almost 70%) forms of Mi-2 proteins: Mi-2α (208 kDa) and Mi-2β (218 kDa). Only Mi-2β seems to be the specific target for autoantibodies. Mi-2 seems to play a role in the regulation of transcription. Mi-2β is a part of a nuclear complex known as nucleosome remodelling deacetylase (NuRD).

The EliA Mi-2 wells are coated with human recombinant Mi-2b protein produced in the baculovirus/insect cell system.

Disease association, antibody prevalence and specificity

  • 15-31% of adult dermatomyositis patients
  • Rare (<1%) in polymyositis patients
  • More than 90% of anti-Mi-2 positive patients have dermatomyositis.
  • The specificity of anti-Mi-2 is very high. In our validation study, none of the 180 disease controls was positive.

In contrast to synthetase antibodies (Jo-1, Pl-7, PL-12)-positive patients, those positive for anti-Mi-2 antibodies show:

  • A relative mild disease course.
  • Rare synovitis exhibitions, lung manifestations or Raynaud’s phenomenon.
  • Good response to glucocorticosteroids.

Mi-2 antibodies are detectable in the early stage of myositis development.

Disease activity

There are no hints that the antibodies correlate with disease activity and could predict any relapse. Regular follow-up testing after diagnosis is therefore not recommended.

When is the measurement recommended?

  • Differential diagnosis of myopathy/myositis
  • Suspicion of idiopathic inflammatory myopathies (IIM)
  • Differential diagnosis of poly-, dermato- and inclusion body myositis
  • Follow-up of a positive EliA CTD Screen, if common antibodies are negative

References

Conrad K et al (2002)  |  Ghirardello A et al (2005)  |  Targoff IN (2007)  |  Targoff IN (2000)

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Fibrillarin  NEW!

Product

Article No.

No. of tests

EliA Fibrillarin 14-5606-01 2x12 tests

 

Promotion material

Performance folder
EliA Fibrillarin (pdf)

Antigen

Synonyms for fibrillarin:

  • Scl-34
  • U3-RNP
  • rRNA 2'-O-methyltransferase

Fibrillarin, a 34 kDa protein, is the main component of the nucleolar U3-RNP complex, which is involved in pre-rRNA processing. Fibrillarin is also a component of other small nucleolar ribonucleoprotein complexes (snoRNP), and is also found in coiled or Cajal bodies.

The EliA Fibrillarin wells are coated with human recombinant fibrillarin produced in the baculovirus/insect cell system.

Disease association, antibody prevalence and specificity

  • 7-14% of patients with scleroderma
  • Up to 64% of patients with diffuse cutaneous SSc

Occur more frequently in a subset of SSc patients who are often of African descent (>50%), male, and with serious cutaneous and visceral disease. It is the second most common ANA antibody in African Americans with SSc (after Scl-70).

Prognostic marker

Markers for diffuse cutaneous SSc are anti-fibrillarin (up to 64%), anti-RNA-Pol III (up to 85%), and anti-Scl70 (up to 71%), while patients with anti-fibrillarin have the worst prognosis, because they are typically associated with multiorgan involvement including small intestinal involvement, renal crisis, pulmonary fibrosis/pulmonary hypertension or muscle inflammation. Anti-fibrillarin positive patients are likely to develop alveolitis, pulmonary fibrosis and later severe vascular pulmonary hypertension, and must be monitored.

Specificity

  • High specificity for scleroderma
  • Rare occurrence in SLE or Raynaud's phenomenon

Disease activity

There are no hints that the antibodies correlate with disease activity and could predict any relapse. Regular follow-up testing after diagnosis is therefore not recommended.

When is the measurement recommended? 

  • Suspicion of scleroderma
  • Differential diagnosis of diseases characterized by Raynaud‘s phenomenon
  • Assessment of members of at-risk group (e.g. persons exposed to silica or mercury)
  • Prognostic use: immunological differential diagnosis to predict the potential development of scleroderma
  • Follow-up of a positive IIF with a fibrillarin-typical pattern

References

Conrad K et al (2002)  |  Pollard KM and Hultman P (2007)  |  Steen VD (2005)  |  Steen VD (2008)  |  Tormey VJ et al. (2001)

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