What is an Anti-La/SSB test?
The Anti-La/SSB test is a blood test that detects autoantibodies against the La/SSB antigen.
Anti-La/SSB antibodies are produced by the immune system and react against proteins found inside the body's cells. They are most commonly associated with Sjögren's disease (Sjögren syndrome) and may also occur in patients with systemic lupus erythematosus (SLE) and other systemic autoimmune diseases.
Anti-La/SSB is commonly tested together with Anti-Ro/SSA antibodies, as these antibodies frequently occur together.
What is the Anti-La/SSB test used for?
The test may be used to:
Support the evaluation of suspected Sjögren's disease
Support the evaluation of systemic lupus erythematosus (SLE)
Help characterize a patient's autoimmune antibody profile
Provide additional information when evaluating systemic autoimmune diseases
Complement testing for Anti-Ro/SSA and other autoimmune antibodies
Anti-La/SSB is considered a supportive marker and should not be used alone to diagnose an autoimmune disease.
Why do I need an Anti-La/SSB test?
Your healthcare provider may request this test if you have symptoms or laboratory findings that suggest an autoimmune connective-tissue disease, such as:
Persistent dry eyes
Persistent dry mouth
Difficulty swallowing dry foods
Swelling of the salivary glands
Joint pain or stiffness
Unexplained fatigue
Skin rashes
Unexplained inflammation
Other symptoms suggestive of Sjögren's disease or SLE
The test may also be included as part of an ENA (Extractable Nuclear Antigen) antibody panel.
What happens during the test?
A small blood sample is collected from a vein in your arm.
The serum is analyzed using an immunological method to detect Anti-La/SSB antibodies.
Depending on the laboratory method, results may be reported as:
Positive/Negative
Detected/Not detected
A numerical antibody concentration or index
The laboratory's specific reference range and cutoff should be used when interpreting the result.
Will I need to do anything to prepare?
Usually, no fasting or special preparation is required.
Tell your healthcare provider about any known autoimmune disease, current symptoms, medications, and previous autoimmune antibody results.
Are there any risks?
The test involves a routine blood collection. You may experience minor discomfort, bruising, or tenderness at the collection site.
Serious complications are very uncommon.
What do the results mean?
Positive result
A positive Anti-La/SSB result means that antibodies against the La/SSB antigen were detected.
Anti-La/SSB antibodies can support the diagnosis of Sjögren's disease, particularly when Anti-Ro/SSA antibodies and compatible clinical findings are also present.
They may also be detected in some patients with SLE and other systemic autoimmune diseases.
However, a positive result does not by itself establish a diagnosis.
The result should be interpreted together with:
Anti-Ro/SSA antibodies
ANA
Rheumatoid factor, when appropriate
Clinical symptoms and examination
Other laboratory findings
Objective assessment of tear and salivary gland function when indicated
Negative result
A negative Anti-La/SSB result means that Anti-La/SSB antibodies were not detected by the assay.
This does not completely exclude Sjögren's disease or another autoimmune condition.
Many patients with Sjögren's disease do not have detectable Anti-La/SSB antibodies. Anti-Ro/SSA is generally a more important serological marker in the evaluation of Sjögren's disease.
Therefore, a negative Anti-La/SSB result should be interpreted together with Anti-Ro/SSA, ANA, symptoms, and other clinical and laboratory findings.
Important note about the results
Anti-La/SSB is an important supportive autoimmune marker, particularly in the evaluation of Sjögren's disease, but it should not be interpreted as a stand-alone diagnostic test.
Anti-La/SSB frequently occurs together with Anti-Ro/SSA. Isolated Anti-La/SSB positivity, particularly when Anti-Ro/SSA is negative, should be interpreted carefully in the context of the patient's clinical findings and the specific assay used.
A negative Anti-La/SSB result does not rule out Sjögren's disease.
The diagnosis of Sjögren's disease, SLE, or another systemic autoimmune disease is based on a combination of clinical findings, autoantibody results, objective tests, and other diagnostic investigations when appropriate.
The exact antibody cutoff and reporting format vary according to the assay and manufacturer. Results should therefore be interpreted according to the laboratory's validated reference criteria.
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