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HelpTest Code SSAB SS-A and SS-B Antibodies, IgG, Serum
Reporting Name
SSA/SSBUseful For
Evaluating patients with signs and symptoms of a connective tissue disease in whom the test for antinuclear antibodies is positive, especially those with signs and symptoms consistent with Sjogren syndrome or lupus erythematosus
This test is not useful in patients without demonstrable antinuclear antibodies.
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SSA | SS-A/Ro Ab, IgG, S | Yes | Yes |
| SSB | SS-B/La Ab, IgG, S | Yes | Yes |
Testing Algorithm
For more information see Connective Tissue Disease Cascade.
Method Name
Multiplex Flow Immunoassay
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.35 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 21 days | |
| Frozen | 21 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | OK |
| Heat-treated specimen | Reject |
Special Instructions
Reference Values
SS-A/Ro ANTIBODIES, IgG
<1.0 U (negative)
≥1.0 U (positive)
Reference values apply to all ages.
SS-B/La ANTIBODIES, IgG
<1.0 U (negative)
≥1.0 (positive)
Reference values apply to all ages.
Day(s) Performed
Monday through Saturday
CPT Code Information
86235 x 2
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| SSAB | SSA/SSB | 87555-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| SSA | SS-A/Ro Ab, IgG, S | 33610-7 |
| SSB | SS-B/La Ab, IgG, S | 33613-1 |
Clinical Information
Sjogren syndrome (SjS) is a heterogeneous systemic autoimmune rheumatic disorder characterized by diverse immunologic responses to SS-A/Ro and SS-B/La antigens.(1) These immune reactivities have been implicated in the destruction of exocrine gland epithelium with demonstration of typical peri-epithelial lymphocytic infiltration, which can vary from sicca syndrome to systemic disease and lymphoma.(2) The SS-A/Ro and SS-B/La system is considered to be a heterogeneous antigenic complex made up of three different proteins (Ro52, Ro60 and La) and four small RNA particles.(1,2) The SS-B/La antigen is a 48 kDa phosphorylated protein that can be found in the nucleus and the cytoplasm and binds to several RNA molecules.(3) SS-B/La appears to be susceptible to proteolysis and degrades into smaller, but immunoreactive, polypeptides.(4)
Unlike antibodies to SS-A/Ro, which are present in SjS and other connective tissue diseases (CTD; systemic lupus erythematosus, systemic sclerosis, inflammatory myopathies, overlap CTD) and primary biliary cholangitis, anti-SS-B/La antibodies are found primarily in patients with SjS.(2,5,6) In addition, SS-A/Ro antibodies may be found alone in many patients with SjS; however, anti-SS-B/La autoantibodies without SS-A/Ro have limited significant association for SjS diagnosis or phenotypic categorization.(2,6,7) Lastly, testing for anti-SS-A/Ro antibodies is included in the 2016 American College of Rheumatology/European League Against Rheumatism classification criteria for primary SjS; whereas, evaluation of anti-SS-B/La antibodies is not required.(8) In a recent multicenter study of more than 10,500 patients with primary SjS, anti-SS-B/La antibodies were detected in 58% of anti-SS-A/Ro antibody-positive cases.(9)
SS-A/Ro is an extractable nuclear antigen composed of two distinct antigens of 52 kDa (Ro52) and 60 kDa (Ro60) combined with cytoplasmic RNA species.(10-12) SS-A/Ro (Ro52 and/or Ro60) antibodies occur in patients with several different connective tissue diseases including SjS, an autoimmune disease that involves primarily the salivary and lachrymal glands, systemic lupus erythematosus (SLE), rheumatoid arthritis, systemic sclerosis (SSc), and idiopathic inflammatory myopathies (IIM).(10-14) SS-A/Ro antibodies are associated with childhood SLE, neonatal SLE, and with congenital heart block in infants born to mothers with SLE.(12,14)
Traditionally, anti-Ro antibodies were detected by indirect immunofluorescence assay on HEp-2 substrates and confirmed by immunodiffusion, immunoblot, or enzyme-linked immunosorbent assay (ELISA), mostly using a mixture of both Ro52 and Ro60 as the antigens.(10) With technological advances in the expression and purification of recombinant proteins, solid-phase immunoassays that allow the separate detection of anti-Ro52 and anti-Ro60 antibodies, such as ELISA, fluorometric enzyme-linked immunoassays (FEIA), chemiluminescence immunoassays (CIA), addressable laser bead immunoassay (ALBIA), particle-based multianalyte technology (PMAT), or autoantigen arrays, became available.(11,12) Based on separate determination of Ro52 and Ro60 antibodies, there is substantial evidence that differential associations of these autoantibodies in patients may corelate with specific phenotypes in SLE (neonatal lupus, and fetal atrioventricular blockade), SjS, SSc, IIM, or primary biliary cholangitis.(10-13,15) Patients who have SjS with antibodies to both Ro52 and Ro60 are characterized by higher prevalence of markers of B-cell hyperactivity and glandular inflammation compared to those with single positivity.(13,15) Although these antibodies are often found together, both autoantibodies have important and distinct diagnostic and predictive attributes and should be distinguished when SS-A/Ro antibody is positive or tested singly.(11,13,15)
Like anti-Ro52 and anti-Ro60 antibodies, anti-SS-B/La autoantibodies are detected using a variety of solid-phase (such as plate, bead or membrane) immunoassays, such ELISAs, FEIA, CIA, ALBIA, PMAT, and dot or line immunoassays.(16)
For more information see Connective Tissue Disease Cascade.
Interpretation
A positive result for SSA (Ro) or SSB (La) antibodies is highly suggestive of a diagnosis of Sjogren syndrome.
The presence of isolated anti-SS-B/La antibody has low positive predictive value of Sjogren syndrome.
A positive result for SS-A/Ro antibodies may be suggestive of connective tissue disease (CTD) such as Sjogren syndrome, systemic lupus erythematosus (SLE), systemic sclerosis, inflammatory myopathies (especially in patients with anti-synthetase syndrome), CTD-associated with interstitial lung diseases, or rheumatoid arthritis.
A positive result for SS-A/Ro antibodies in a woman with SLE prior to delivery indicates an increased risk of congenital heart block in the neonate.
Differential testing for Ro52 and Ro60 antibodies in patients positive for SS-A/Ro may be useful in the diagnosis of specific CTD clinical subset, disease stratification, and prognosis. Consider testing for Ro52 and Ro60 antibodies (ROPAN / Ro52 and Ro60 Antibodies, IgG, Serum) if the patient is positive for SS-A/Ro.
Cautions
No significant cautionary statements
Method Description
Recombinant SS-A/Ro 52 kDa, affinity-purified SS-A/Ro 60 kDa, and affinity-purified SS-B antigen are coupled covalently to polystyrene microspheres that are impregnated with fluorescent dyes to create a unique fluorescent signature. SS-A/Ro antibodies, if present in diluted serum, bind to the SS-A/Ro antigens on the microspheres, and SS-B/La antibodies, if present, bind to the SS-B antigen on the microspheres. The microspheres are washed to remove extraneous serum proteins. Phycoerythrin (PE)-conjugated antihuman IgG antibody is then added to detect IgG anti-SS-A/Ro or anti-SS-B/La bound to the microspheres. The microspheres are washed to remove unbound conjugate, and bound conjugate is detected by laser photometry. A primary laser reveals the fluorescent signature of each microsphere to distinguish it from microspheres that are labeled with other antigens, and a secondary laser reveals the level of PE fluorescence associated with each microsphere. Results are calculated by comparing the median fluorescence response for SS-A/Ro and SS-B/La microspheres to a 4-point calibration curve.(Package insert: Bioplex 2200 ANA Screen. Bio-Rad Laboratories; 02/2019)