Version July 2025
INTRODUCTION —
Autoantibodies directed against Ro/SSA and La/SSB autoantigens were originally identified in patients with Sjögren's disease (SjD) and systemic lupus erythematosus (SLE). Subsequent studies showed that anti-Ro/SSA antibodies may be present in patients with other autoimmune diseases, including systemic sclerosis (SSc), idiopathic inflammatory myopathies (IIM), interstitial lung disease (ILD), mixed connective tissue disease (MCTD), primary biliary cholangitis (PBC; previously referred to as primary biliary cirrhosis), and rheumatoid arthritis (RA). Anti-Ro/SSA antibodies may be the only autoantibodies present in a subset of patients with antinuclear antibody (ANA)-negative SLE. Additionally, anti-Ro/SSA antibodies (with or without anti-La/SSB antibodies) identify pregnant women who are at increased risk of having a child with neonatal lupus (NL). (See "Neonatal lupus: Epidemiology, pathogenesis, clinical manifestations, and diagnosis".)
The anti-Ro/SSA and anti-La/SSB antibody systems and the clinical significance of these antibodies are reviewed here. An overview of the ANAs important in SLE and in related autoimmune diseases and the clinical significance of autoantibodies directed against double-stranded deoxyribonucleic acid (dsDNA), U1 ribonucleoprotein (RNP), Sm, and ribosomal P proteins are reviewed separately:
●(See "Measurement and clinical significance of antinuclear antibodies".)
●(See "Antibodies to double-stranded (ds)DNA, Sm, and U1 RNP".)
●(See "Antiribosomal P protein antibodies".)
Ro/SSA ANTIGENS —
Serum containing autoantibodies directed against the Ro/SSA antigens may recognize one or both of two cellular proteins with molecular weights of approximately 52 and 60 kD [1-4]. These autoantigens are referred to as "Ro52" and "Ro60," respectively. Ro52 and Ro60 do not have amino acid sequence homology; autoantibodies directed against Ro52 do not cross-react with Ro60, and vice versa. While the two autoantigens were originally thought to interact with each other, subsequent studies showed that the two proteins reside in distinct cellular compartments: Ro60 localizes to the nucleus and nucleolus while Ro52 localizes to the cytoplasm.
Ro60 (also known as TROVE2) — The amino acid sequence of the Ro60 autoantigen was described in the late 1980s [1,2]; Ro60 was shown to bind small, non-coding ribonucleic acids (RNAs) termed "Y RNAs." Although the function of Y RNAs is unknown, one report suggests that Y RNAs may be a source of micro (mi)RNA molecules, which have a role in the regulation of messenger (m)RNA stability and translation [5]. The crystal structure of Ro60 suggests that the protein can bind to both single- and double-stranded (ds)RNA. The protein may function as an "RNA chaperone" that binds to misfolded pre-5S ribosomal RNA and may hasten the degradation of the defective molecule. Ro60 may also bind to other cellular and viral RNAs in the cell, including Epstein-Barr virus (EBV) early RNA 1 (EBER1) [6]. Mice that lack the functional gene encoding Ro60 develop an autoimmune syndrome characterized by the presence of anti-ribosome and anti-chromatin antibodies and the development of glomerulonephritis [7], suggesting that Ro60 may have an important role in preventing systemic autoimmune disease.
Ro52 (also known as TRIM21) — The amino acid sequence of the Ro52 autoantigen was reported in 1991 [3]. Ro52 is an interferon-inducible protein that belongs to the "tripartite motif" family of proteins. Ro52 contains an amino (N)-terminal RING finger domain, followed by B-box and coiled-coil domains and by a carboxy (C)-terminal B30.2 or "PRYPRY" domain. The protein localizes to the cytoplasm and functions as an E3 ubiquitin ligase, an enzyme that adds ubiquitin molecules to target proteins [4].
Ro52 interacts with a broad range of substrates and may either enhance or inhibit the function of target proteins. It binds the Fc portion of immunoglobulin G (IgG) molecules, via its C-terminal B30.2 domain, and catalyzes the polyubiquitination of misfolded IgG, thereby hastening its degradation in proteasomes [8,9]. The presence of a domain that can bind the Fc portion of antibody molecules raises the possibility that Ro52 has a role in "intracellular antibody immunity." Antibody-coated viral particles might be carried inside the cell during infection. Interaction between Ro52 and the antibody-pathogen complex may result in ubiquitination and subsequent degradation of the pathogen [10].
Ro52 may also have important roles in the regulation of inflammation. Ro52 adds an ubiquitin molecule to activated inhibitor of nuclear factor kappa-B kinase subunit beta (IKKB) and downregulates proinflammatory nuclear factor kappa-B (NFKB) signaling [11]. Ro52 also inhibits inflammation by targeting interferon regulatory factors (IRF) 3 and 7 for ubiquitin-mediated degradation [12,13]. Consistent with the effects of Ro52 on NFKB signaling and IRF stability, mice that lack Ro52 develop an autoimmune disease characterized by hypergammaglobulinemia and kidney disease [14,15].
Ro52, like Ro60 and La (see 'La/SSB antigen' below), may also have a role in the regulation of mRNA stability. Ro52 interacts with and enhances the activity of decapping protein (DCP) 2 [16], a protein that removes the 5' cap from mRNA molecules. Removal of the 5' cap exposes mRNA molecules to degradation by exoribonuclease I.
La/SSB ANTIGEN —
Autoantibodies directed against the La/SSB autoantigen (La) interact with a 47-kD protein, which shuttles between the nucleus and cytoplasm but which is predominantly found in the nucleus [17]. A complementary DNA (cDNA) encoding La was identified in 1988 [18]. The N-terminus of the protein contains a "La" RNA-binding domain and an adjacent RNA recognition motif (RRM), which cooperate to bind RNA. The C-terminus of the protein contains a second RRM followed by a short basic motif ("SBF" domain) and a nuclear localization sequence [19]. The N-terminal portion of La mediates the interaction with the 3' end of RNA polymerase III transcripts [20]. La participates in the processing of small, noncoding RNAs such as ribosomal 5S RNA.
La also binds cellular transfer (t)RNAs, as well as viral RNA molecules, including those produced by Epstein-Barr virus (EBV), Hepatitis A and C viruses, respiratory syncytial virus, adenovirus, and human immunodeficiency virus (HIV) [17,21-25]. La may regulate the translation of viral RNAs by enhancing internal ribosomal entry site function. One report suggests that La has a critical role in regulating RNA interference (RNAi) by enhancing RNAi turnover in the RNA-induced silencing complex (RISC) [26], suggesting that La has a role in the regulation of messenger (m)RNA stability and translation. A mouse model that lacks the La protein has not been reported.
DETECTION OF ANTI-Ro AND ANTI-La ANTIBODIES
Immunofluorescence staining on HEp-2 substrates — Patients with anti-Ro antibodies who lack other autoantibodies may have a falsely negative antinuclear antibody (ANA) test using indirect immunofluorescence and the traditional human epithelial cell line-2 (HEp-2) cell substrate. This is because Ro60 and Ro52 immunoreactivity may be lost during the preparation of the cells.
●Anti-Ro60 antibodies – To facilitate detection of anti-Ro60 antibodies using indirect immunofluorescence, some laboratories use a genetically modified HEp-2 cell substrate ("HEp-2000"). Approximately 20 percent of HEp-2000 cells express a transfected complementary DNA (cDNA) encoding Ro60, resulting in overexpression of the autoantigen in this subset of cells [27,28]. If anti-Ro60 antibodies are the only autoantibodies present in a patient’s serum, nucleolar and nuclear speckled staining patterns will be present in the transfected cells. No staining will be present in the remaining cells (picture 1).
A limitation of the HEp-2000 substrate for the detection of anti-Ro60 antibodies occurs when other autoantibodies are present in addition to anti-Ro60 antibodies. As an example, antibodies directed against DNA will produce a homogeneous nuclear staining pattern in all cells and may obscure the characteristic anti-Ro60 pattern (which would otherwise be detected in a subset of the HEp-2000 cells). The use of either the classic HEp-2 cell or the modified HEp-2000 substrate was supported by experts from the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM), the European Autoimmune Standardization Initiative (EASI), and the International Consensus on ANA Patterns (ICAP) [29,30]. However, in laboratories using the traditional HEp-2 cell substrate, a solid phase assay, instead of indirect immunofluorescence, is required to detect anti-Ro60 antibodies.
●Anti-Ro52 antibodies – Antibodies directed against Ro52, like those directed against Ro60, are difficult to detect by indirect immunofluorescence using the traditional HEp-2 cell substrate. In addition, when overexpressed in HEp-2 cells, Ro52 localizes to the cell cytoplasm (picture 2). Because Ro52 is not a nuclear autoantigen and because anti-Ro52 autoantibodies are difficult to detect using the HEp-2 cell substrate, a patient who has only anti-Ro52 antibodies may have a negative test for ANA. A genetically-modified HEp-2 cell line overexpressing Ro52 has not been developed for commercial use.
●Anti-La antibodies – Although La has been shown to shuttle between the nucleus and cytoplasm, the protein is predominantly found in the nucleus of HEp-2 cells. Autoantibodies directed against La produce a speckled nuclear staining pattern (picture 3).
Solid phase assays — Most laboratories have adopted solid phase assays to detect anti-Ro and anti-La antibodies. Solid phase assays include enzyme-linked immunosorbent-, antigen-coated fluorescent microsphere-, and flow cytometry-based- assays. Solid phase assays use either native or recombinant protein as substrate.
With the recognition that the autoantigen designated "Ro" consists of two distinct proteins (Ro60 and Ro52), solid phase immunoassays have been developed for each [31]. However, many commercial laboratories use a single "anti-Ro" antibody test for both anti-Ro60 and anti-Ro52 antibodies using a combination of the two antigens, despite the different clinical information provided by the individual detection of anti-Ro60 and anti-Ro52 autoantibodies (see 'Clinical significance' below). In addition, assays that combine Ro52 and Ro60 antigens may fail to detect up to 20 percent of patients who have antibodies against either Ro52 or Ro60 [31].
CLINICAL SIGNIFICANCE
Overview of antibody patterns — The reported prevalence of anti-Ro and anti-La antibodies in patients with autoimmune disease depends to a great extent on the method used to detect the autoantibodies.
Anti-Ro antibodies (combined assay) — Many commercial laboratories use a single "anti-Ro" antibody assay to detect both anti-Ro60 and anti-Ro52 antibodies (see 'Solid phase assays' above). Using this combined assay, anti-Ro antibodies may be present in patients with a range of autoimmune disorders, including systemic lupus erythematosus (SLE; 32 percent), Sjögren's disease (SjD; 59 percent), idiopathic inflammatory myopathies (IIM; 19 percent), systemic sclerosis (SSc; 21 percent), mixed connective tissue disease (MCTD; 29 percent [32]), and rheumatoid arthritis (RA; 15 percent), as well as primary biliary cholangitis (PBC; previously referred to as primary biliary cirrhosis), interstitial lung disease (ILD) [33], and undefined connective tissue disease (UCTD) [34]. Anti-Ro antibodies may be the only autoantibodies present in more than half of the patients with "antinuclear antibody (ANA)-negative" SLE and may also be the first detectable autoantibodies preceding the development of SLE and SjD in asymptomatic individuals. Females with anti-Ro antibodies (with or without anti-La antibodies and with or without autoimmune disease) are at increased risk for having a child with neonatal lupus (NL). (See 'Disease associations' below and 'Anti-Ro antibodies preceding autoimmune disease' below.)
Anti-Ro60 versus anti-Ro52 antibodies (separate assays) — Some laboratories use assays that are able to discriminate between anti-Ro60 and anti-Ro52 antibodies (see 'Detection of anti-Ro and anti-La antibodies' above). Both anti-Ro60 and anti-Ro52 may be seen in patients with SLE [31], SjD [35,36], SSc, and MCTD [32,37]. Antibodies to Ro52, but not Ro60, have also been detected in patients with IIM. For certain conditions (eg, SjD, IIM, SSc), the presence of anti-Ro-52 may portend more severe disease and/or lung involvement [32,35,36,38,39]. (See 'Disease associations' below.)
Anti-La antibodies — In contrast to anti-Ro antibodies, which may be present in a variety of autoimmune diseases, anti-La antibodies are specific for the diagnosis of SjD and SLE [40]. In addition, as with anti-Ro antibodies, anti-La antibodies may be detected in the mothers of children who are born with NL [41,42]; these women may or may not have evidence of systemic autoimmune disease. (See 'Disease associations' below.)
Anti-Ro antibody negative, anti-La antibody positive — While anti-La antibodies are rarely detected in the absence of anti-Ro antibodies, isolated anti-La antibodies have been described in a small number of patients with SjD and PBC and in mothers of children with NL. In the absence of anti-Ro antibodies and other indications of SjD or SLE, the clinical significance of anti-La antibodies is uncertain. (See 'Disease associations' below.)
Disease associations
Sjögren's disease — Patients with SjD frequently have detectable anti-Ro antibodies (with or without co-occurring anti-La antibodies) when serum is tested using the HEp-2000 substrate and indirect immunofluorescence or by solid phase immunoassay. Using the traditional human epithelial cell line-2 (HEp-2) cell substrate, the indirect immunofluorescence test for ANA may be falsely negative in patients who only have anti-Ro antibodies (see 'Immunofluorescence staining on HEp-2 substrates' above). In a study of 335 patients with SjD, 74 had both anti-Ro and anti-La antibodies, 85 had only anti-Ro antibodies, and only four had only anti-La antibodies [43]. A study involving the Sjögren's Syndrome International Clinical Alliance (SICCA) cohort concluded that patients who were anti-La antibody positive but anti-Ro antibody negative were unlikely to have SjD [44]. (See "Diagnosis and classification of Sjögren's disease", section on 'Antibodies to Ro/SSA and La/SSB'.)
Because anti-Ro autoantibodies are relatively specific for SjD, an American-European Consensus Group included the presence of anti-Ro with or without anti-La antibodies as one of six classification criteria for this disease [45]. A subsequent American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR; formerly known as European League Against Rheumatism) classification system for primary SjD gave even greater weight to the presence of anti-Ro antibodies. (See "Diagnosis and classification of Sjögren's disease", section on 'Classification criteria'.)
The type of anti-Ro antibody (ie, anti-Ro52 versus anti-Ro60) detected in a patient’s serum may be clinically significant. In patients with SjD, anti-Ro60 and anti-Ro52 were detected in 67 and 75 percent of affected individuals; the presence of anti-Ro52 antibodies may be associated with more severe disease [35] and development of ILD [36].
Systemic lupus erythematosus — The prevalence of anti-Ro60 and anti-Ro52 antibodies in patients with SLE is reported to be 49 and 43 percent, respectively [31]. Anti-La antibodies are relatively specific for SLE and SjD [40]. (See "Systemic lupus erythematosus in adults: Clinical manifestations and diagnosis", section on 'Laboratory testing'.)
As described above, sera that have only anti-Ro60 and/or anti-Ro52 autoantibodies may be reported to be "ANA-negative" (see 'Immunofluorescence staining on HEp-2 substrates' above). When evaluating patients who are thought to have SLE but who are ANA-negative by indirect immunofluorescence, it is important to request testing for anti-Ro antibodies using a solid phase assay [46]. (See 'Immunofluorescence staining on HEp-2 substrates' above and "Systemic lupus erythematosus in adults: Clinical manifestations and diagnosis", section on 'ANA-negative SLE'.)
Neonatal lupus — NL is an autoimmune disease that develops due to the passive transfer of autoantibodies from mother to fetus. Most infants with NL are born to mothers with anti-Ro antibodies, with or without anti-La antibodies. In a study of 201 mothers of children with NL, 113 had antibodies directed against both Ro and La, 85 had antibodies directed against Ro alone, and only three patients were found to have anti-La antibodies in the absence of anti-Ro antibodies [41].
The most serious, although rare, complication of NL in the neonate is complete heart block. Some asymptomatic mothers with anti-Ro antibodies (with or without anti-La antibodies) may eventually develop a related autoimmune disease. The epidemiology, pathogenesis, and clinical features of NL, prenatal surveillance for heart block in the setting of maternal anti-Ro/SSA antibodies, and management of congenital complete heart block are presented separately. (See "Neonatal lupus: Epidemiology, pathogenesis, clinical manifestations, and diagnosis" and "Congenital third-degree (complete) atrioventricular block".)
Cutaneous lupus erythematosus — Anti-Ro antibodies are frequently detected in patients with dermatologic manifestations of SLE. In one study, anti-Ro antibodies were detected in 173 of 235 (74 percent) of patients with subacute cutaneous lupus erythematosus (SCLE) [47]. The relationship between anti-Ro antibodies and cutaneous photosensitivity is uncertain. One report suggests that the presence of anti-Sm antibodies, rather than anti-Ro antibodies, is associated with photosensitivity in patients with SLE [48]. (See "Overview of cutaneous lupus erythematosus", section on 'Subacute cutaneous lupus erythematosus'.)
Other autoimmune diseases — Anti-Ro antibodies may be present in patients with other autoimmune diseases including IIM, PBC, RA, and MCTD:
●IIM – Anti-Ro52 antibodies but not anti-Ro60 antibodies were detected in patients with IIM (35 versus 0 percent) [32]. In a study of anti-Jo-1 antibody-positive patients with IIM, 36 of 89 consecutive patients (40 percent) had coexisting anti-Ro52 antibodies [37]. The presence of anti-Ro52 antibodies appeared to identify a subset of anti-Jo-1 antibody-positive patients with more severe muscle and joint disease.
●PBC — Anti-Ro52 antibodies were detected in 28 to 32 percent of patients with PBC and the presence of these antibodies provide an important clue to the diagnosis of this treatable, but sometimes asymptomatic, autoimmune liver disease [49,50]. The pattern of autoantibodies varies; among 165 PBC patients with at least one autoantibody associated with sicca syndrome (ie, anti-Ro, anti-La, and/or anticentromere antibodies), 58 were anti-Ro and anti-La antibody-positive, 61 had only anti-Ro antibodies, and 2 had only anti-La antibodies [51]. (See "Clinical manifestations, diagnosis, and prognosis of primary biliary cholangitis", section on 'Laboratory tests'.)
●RA – Anti-Ro antibodies have also been detected in 6 to 12 percent of patients with RA [52,53]. No difference was seen between the clinical presentations of anti-Ro antibody-positive versus anti-Ro antibody-negative patients. However, one study suggests that RA patients with anti-Ro antibodies may have a poorer clinical response to treatment with infliximab, a tumor necrosis factor (TNF) inhibitor, compared with patients lacking such autoantibodies [54].
●Other autoimmune diseases – Anti-Ro52 antibodies were more common than anti-Ro60 in patients with SSc (19 versus 6 percent) and MCTD (29 versus 19 percent) [32]. The presence of anti-Ro52 antibodies may identify patients with autoimmune disease who are at increased risk of interstitial lung fibrosis [32,38,55].
Anti-Ro antibodies preceding autoimmune disease — Autoantibodies may precede the diagnosis of SLE by years, if not decades. In a study using stored serum samples from 130 individuals who subsequently developed SLE, anti-Ro antibodies were detected in 48 percent of patients [56]. The mean interval between the dates of the stored serum sample in which anti-Ro antibodies were present and the diagnosis of SLE was more than 3.6 years. Relative to all other autoantibodies tested, anti-Ro antibodies were the first to develop in patients who were eventually diagnosed with SLE. In a study of 175 serum samples obtained from 117 individuals prior to a diagnosis of SjD, anti-Ro antibodies were detected a median of four years prior to diagnosis [57]. The number of healthy individuals who are anti-Ro antibody positive and never develop an autoimmune disease is unknown.
INDICATIONS FOR ANTI-RO AND ANTI-LA TESTING —
The decision to obtain testing for anti-Ro and anti-La antibodies, using solid phase assays, depends upon the clinical setting. Patients in whom testing for anti-Ro and anti-La antibodies may be indicated include:
●Patients with symptoms that suggest Sjögren's disease (SjD), such as xerostomia, keratoconjunctivitis sicca, and/or salivary and lacrimal gland enlargement, regardless of antinuclear antibody (ANA) status. (See 'Sjögren's disease' above and "Diagnosis and classification of Sjögren's disease" and "Diagnosis and classification of Sjögren's disease", section on 'Diagnostic testing'.)
●Patients suspected of having systemic lupus erythematosus (SLE). Such testing should employ a solid phase assay because anti-Ro antibodies may not be detected by indirect immunofluorescence using a traditional human epithelial cell line-2 (HEp-2) cell substrate. (See 'Systemic lupus erythematosus' above and "Systemic lupus erythematosus in adults: Clinical manifestations and diagnosis", section on 'Laboratory testing'.)
●Females who are considering pregnancy and who have risk factors for developing neonatal lupus (eg, patients with SLE, SjD, or history of giving birth to a child with congenital heart block). It is also the author's practice to test for anti-Ro antibodies in females who have a positive test for ANA (without defined autoimmune disease) and are considering pregnancy. Maternal screening for anti-Ro and anti-La is discussed in more detail elsewhere. (See "Neonatal lupus: Epidemiology, pathogenesis, clinical manifestations, and diagnosis", section on 'Maternal screening' and "Pregnancy in women with systemic lupus erythematosus", section on 'Baseline evaluation'.)
SOCIETY GUIDELINE LINKS —
Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Antinuclear antibodies".)
SUMMARY AND RECOMMENDATIONS
●Ro/SSA antigens – Serum containing autoantibodies directed against the Ro/SSA autoantigens may recognize one or both of two cellular proteins with molecular weights of approximately 52 and 60 kD; the autoantigens are referred to as "Ro52" and "Ro60," respectively. Ro60 is localized to the nucleus and nucleolus, and Ro52 is localized to the cytoplasm. (See 'Ro/SSA antigens' above.)
●La/SSB antigen – Autoantibodies directed against the La/SSB autoantigen (La) interact with a 47-kD protein, which shuttles between the nucleus and cytoplasm but which is predominantly found in the nucleus. (See 'La/SSB antigen' above.)
●Detection of anti-Ro and anti-La antibodies – Anti-Ro and anti-La antibodies are generally detected using solid phase assays, including enzyme-linked immunosorbent assays (ELISA) and flow cytometry-based assays, with either native or recombinant protein as substrate. Anti-Ro antibodies may not be detected by indirect immunofluorescence using a traditional human epithelial cell line-2 (HEp-2) cell substrate. (See 'Detection of anti-Ro and anti-La antibodies' above.)
●Clinical significance – The combination of anti-Ro and anti-La antibodies is relatively specific for the diagnoses of systemic lupus erythematosus (SLE) and Sjögren's disease (SjD). Anti-Ro antibodies may be the only autoantibodies present in more than half of the patients with "antinuclear antibody (ANA)-negative" SLE. Anti-Ro antibodies are not specific for SLE or SjD and may also be present in a range of autoimmune disorders, including idiopathic inflammatory myositis (IIM), systemic sclerosis (SSc), mixed connective tissue disease (MCTD), and primary biliary cholangitis (PBC; previously referred to as primary biliary cirrhosis). Females with anti-Ro (with or without co-occurring anti-La) autoantibodies are at increased risk for having a child with neonatal lupus (NL). (See 'Clinical significance' above.)
●Indications for anti-Ro and anti-La testing – Patients for whom testing for anti-Ro and anti-La antibodies may be indicated include (see 'Indications for anti-Ro and anti-La testing' above):
•Patients with findings that suggest SjD
•Patients with suspected SLE
•Females who are considering pregnancy and who have risk factors for developing NL (See "Neonatal lupus: Epidemiology, pathogenesis, clinical manifestations, and diagnosis", section on 'Maternal screening'.)
ACKNOWLEDGMENT —
The UpToDate editorial staff acknowledges Morris Reichlin, MD, who contributed to an earlier version of this topic review.
