Test Id : ROPAN

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial

0.8 mL

Evaluating patients at risk for connective tissue disease with or without interstitial lung disease

Differentiation of antibodies to Ro52 and Ro60 in patients known to be positive for anti-SS-A (Ro) antibodies

The SS-A/Ro is part of the Ro/La heterogeneous antigenic complex which is made up of three unique proteins (52 kDa Ro, 60 kDa Ro and La) and four small RNA particles.(1,2) Unlike antibodies to SS-B/La that are less common, reported separately and mainly associated with a diagnosis of primary Sjogren’s syndrome, antibodies to SS-A/Ro are the most prevalent specificity among many autoimmune diseases such as primary Sjogren’s syndrome (SS), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), idiopathic inflammatory myopathy (IIM), rheumatoid arthritis (RA), and primary biliary cholangitis (PBC).(2-4) In addition, children born to mothers positive for anti-SS-A/Ro antibodies are at increased risk for congenital heart block.(3)

Historically, Ro52 and Ro60 autoantibodies were considered as a uniform autoantibody-system. Therefore, when anti-Ro52 or anti-Ro60 antibody is positive, the result was typically reported as anti-SSA/Ro antibody positive.(4,5) However, recent studies have provided evidence that Ro60 and Ro52 are not part of a stable macromolecular complex and that anti-Ro52 and anti-Ro60 antibodies have different clinical associations with implications for diagnosis, prognosis and patient management.(4-6)

The Ro52 antigen is also known as TRIM21; this protein has E3 ligase activity and functions in the process of ubiquitination.(1-3) The Ro60 antigen is a 60-kDa RNA-binding protein known to have repair functions for misfolded RNA.(1-3)

Individuals positive for anti-SS-A/Ro antibodies may react with either Ro52, Ro60, or both antigens.(4-6) Patients with only anti-Ro52 antibodies display a higher incidence of IIM,SSc, or interstitial lung disease (ILD).(7). Anti-Ro52 antibodies, in conjunction with antisynthetase antibodies such Jo-1 (others include PL-7, PL-12, EJ, and OJ) are also highly associated with ILD in patients with IIM.(7,8) In contrast, isolated anti-Ro60 antibodies are associated with increased risk for SLE and, to a lesser degree, for SS.(8) Positivity for both anti-Ro52 and anti-Ro60 antibodies are most strongly associated with SS; this association is even stronger if anti-SS-B/La antibodies are also detected.(9) The presence of anti-Ro52 and anti-Ro60 antibodies may also be observed in patients with SLE.(10)

Ro52 ANTIBODY, IgG

<20 CU (negative)

> or =20 CU (positive)

Reference values apply to all ages

Ro60 ANTIBODY, IgG

<20 CU (negative)

> or =20 CU (positive)

Reference values apply to all ages

The presence of antibodies to both SS-A 52 (Ro52) or SSA 60 (Ro60) is highly suggestive of a diagnosis of Sjogren syndrome (SS), with positivity for Ro60 alone more likely to be associated with systemic lupus erythematosus (SLE).

Antibodies to Ro52 may be present in patients with idiopathic inflammatory myopathy (IIM), systemic sclerosis (SSc) or overlap connective tissue disease (CTD). In CTD, antibodies to Ro52 alone, or in association with other specific autoantibodies may be associated with interstitial lung diseases.

Negative results for antibodies to Ro52 and Ro60 does not exclude the possibility of any CTD, including SS, SLE, SSc, and IIM.

Results from this testing should be interpreted in the context of clinical findings and other laboratory testing. Tests cannot be exclusively relied upon to establish a diagnosis for any connective tissue disease or related disorder, including systemic lupus erythematosus, Sjogren syndrome (SS), systemic sclerosis, or idiopathic inflammatory myopathy.

When assessed by standard SS-A (Ro) solid-phase immunoassays, such as enzyme immunoassays using combined antigens, some antibodies specific for either SSA 52 (Ro52) or SSA 60 (Ro60) may not be detected due to masking of target epitopes. In addition, multiplex bead assays with Ro52 or Ro60 antigens may simply be reported as SS-A/Ro positive without differentiation of the specific positive antibody.

1. Schulte-Pelkum J, Fritzler M, Mahler M: Latest update on the Ro/SS-A autoantibody system. Autoimmun Rev. 2009;8(7):632-637

2. Defendenti C, Atzeni F, Spina MF, et al. Clinical and laboratory aspects of Ro/SSA-52 autoantibodies. Autoimmun Rev. 2010;10(3):150-154

3. Fayyaz A, Kurien BT, Scofield H. Autoantibodies in Sjogren's syndrome. Rheum Dis Clin North Am. 2016;42(3):419-434

4. Armagan B, Robinson SA, Bazoberry A, et al. Antibodies to both ro52 and ro60 for identifying Sjogren's syndrome patients best suited for clinical trials of disease-modifying therapies. Arthritis Care Res (Hoboken). 2022;74(9):1559-1565

5. Robbins A, Hentzien M, Toquet S, et al: Diagnostic utility of separate anti-Ro60 and anti-Ro52/TRIM21 antibody detection in autoimmune diseases. Front Immunol. 2019;10:444

6. Lee AYS, Reed JH, Gordon TP. Anti-Ro60 and anti-Ro52/TRIM21: Two distinct autoantibodies in systemic autoimmune diseases. J Autoimmun. 2021;124:102724

7. Chan EKL. Anti-Ro52 autoantibody is common in systemic autoimmune rheumatic diseases and correlating with worse outcome when associated with interstitial lung disease in systemic sclerosis and autoimmune myositis. Clin Rev Allergy Immunol. 2022;63(2):178-193

8. Gkoutzourelas A, Liaskos C, Mytilinaiou MG, et al. Anti-Ro60 seropositivity determines anti-ro52 epitope mapping in patients with systemic sclerosis. Front Immunol. 2018;9:2835

9. Deroo L, Achten H, De Boeck K, et al. The value of separate detection of anti-Ro52, anti-Ro60 and anti-SSB/La reactivities in relation to diagnosis and phenotypes in primary Sjögren's syndrome. Clin Exp Rheumatol. 2022;40(12):2310-1317

10. Zampeli E, Mavrommati M, Moutsopoulos HM, Skopouli FN. Anti-Ro52 and/or anti-Ro60 immune reactivity: autoantibody and disease associations. Clin Exp Rheumatol. 2020;38 Suppl 126(4):134-141

Paramagnetic beads are coated with purified recombinant Ro52 protein or purified recombinant Ro60 protein. The serum sample is diluted in assay buffer and incubated with the beads. Antibodies to Ro52 or Ro60 bind to their respective beads and are detected by anti-human IgG antibody conjugated with isoluminol. With addition of trigger reagents, a luminescent reaction is produced by the isoluminol conjugate. The light produced by the reaction is measured by a photomultiplier, proportional to the amount of antibodies that are bound to the beads. The antibodies are quantified according to the working curve on the instrument. Anti-Ro52 and anti-Ro60 are reported in Chemiluminescent Units (CU) as derived from the relative light units measured from each sample.(Package insert: QUANTA Flash Ro52 Reagents, Inova Diagnostics; 06/2019; QUANTA Flash Ro60 Reagents, Inova Diagnostics; 10/2019)

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This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

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