Norm of Anti-La/SS-B Test
Usage of Anti-La/SS-B Test
Differential diagnosis of systemic lupus erythematosus (SLE), Sjögren's syndrome, and mixed connective tissue disease.
Positive.
Antinuclear antibody (ANA)–negative lupus, congenital heart block, neonatal lupus, Sjögren's syndrome. Drugs include terbinafine.
Description of Anti-La/SS-B Test
Anti-La/SS-B is an autoantibody characteristically found in high titers in clients with primary Sjögren's syndrome or Sjögren's syndrome with SLE. The SS-B(La) are antibodies directed against ribonucleic acid (RNA) protein particles that are a cofactor in RNA polymerase III. Although electrophoresis is the most sensitive method for detecting anti-La/SS-B, immunodiffusion is the method most commonly used.
Professional Considerations of Anti-La/SS-B Test
Consent form NOT required.
Preparation
- Tube: Red topped, red/gray topped, or gold topped.
Procedure
- Draw a 4-mL blood sample.
Postprocedure Care
- Transport the specimen to the laboratory for immediate spinning.
Client and Family Teaching
- Results may not be available for several days if testing is not performed on site.
Factors That Affect Results
- None found.
Other Data
- This test is less sensitive but more specific for primary Sjögren's syndrome than the anti-Ro/SS-A test.
- The presence of both anti-La/SS-B and anti-Ro/SS-A antibodies is generally associated with a milder form of SLE.
- Clients who are positive for antinuclear antibody and who have SS-A, but not SS-B, are likely to have nephritis.
