What is the role of SSA and SSB antibody testing in the diagnosis of Sjögren syndrome?

Updated: Mar 05, 2021
  • Author: Sriya K Ranatunga, MD, MPH; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Antibodies against SSA/Ro are found in approximately 50% of patients with the disease (75% of patients with primary Sjögren syndrome and 15% of patients with secondary Sjögren syndrome). Thus, the absence of anti-SSA/Ro antibodies does not eliminate the diagnosis of primary or secondary Sjögren syndrome.

Anti-Ro is a polyclonal antibody directed against nuclear and nucleolar RNA binding protein of 60KD or cytoplasmic protein of 52KD (E3 ubiquitin ligase) . Patients can have a negative ANA and a positive Ro antibody test if they only have anti-Ro against cytoplasmic protein of 52KD.

Anti-La is an oligoclonal antibody that is predominantly directed against nuclear 47KD RNA binding protein.  

Antibodies against SSA/Ro are present in 50% of patients with SLE and are sometimes found in healthy individuals. Thus, the presence of antibody against SSA/Ro cannot by itself be used to establish a diagnosis of Sjögren syndrome.

Antibodies against SSB/La are present in 40-50% of patients with primary Sjögren syndrome and in 15% of patients with SLE. Finding antibodies against SSB/La in patients without antibodies against SSA/Ro is unusual, but this combination has occurred in patients with primary biliary cirrhosis and autoimmune hepatitis.

Titers of anti-SSA/Ro and anti-SSB/La antibodies do not reflect disease activity. Current enzyme-linked immunosorbent assay (ELISA) tests for these antibodies are more sensitive than previous tests. Thus, the specificity is lower.

Antibodies against SSA/Ro are also associated with the annular erythematous lesions of subacute cutaneous lupus. They are also found in the mothers of newborns with neonatal lupus syndromes and congenital heart block, and some of these mothers have or will develop Sjögren syndrome.


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