From the Guidelines
Systemic lupus erythematosus (SLE) is characterized by several antibodies that are commonly positive in patients with this autoimmune disease, including anti-nuclear antibody (ANA), anti-double-stranded DNA (anti-dsDNA) antibodies, anti-Smith (anti-Sm) antibodies, anti-ribonucleoprotein (anti-RNP), anti-Ro/SSA, anti-La/SSB, and antiphospholipid antibodies. The most significant antibody is anti-nuclear antibody (ANA), which is positive in over 95% of SLE patients, making it highly sensitive but not specific for the disease 1. Anti-double-stranded DNA (anti-dsDNA) antibodies are more specific for SLE and correlate with disease activity, particularly with lupus nephritis 1.
Key Antibodies in SLE
- Anti-nuclear antibody (ANA): highly sensitive but not specific for SLE
- Anti-double-stranded DNA (anti-dsDNA) antibodies: more specific for SLE and correlate with disease activity
- Anti-Smith (anti-Sm) antibodies: highly specific for SLE but less sensitive
- Anti-ribonucleoprotein (anti-RNP): associated with mixed connective tissue disease but also seen in SLE
- Anti-Ro/SSA and anti-La/SSB: linked to neonatal lupus and congenital heart block when present in pregnant women
- Antiphospholipid antibodies: increase risk for thrombosis and pregnancy complications
Monitoring and Diagnosis
These antibodies help in diagnosis, monitoring disease activity, and predicting specific organ involvement in SLE patients 1. Complement levels (C3 and C4) are often decreased during active disease due to consumption in immune complex formation. The monitoring of autoantibodies and complement levels, including ANA, anti-dsDNA, anti-Ro, anti-La, anti-RNP, anti-Sm, anti-phospholipid, C3, and C4, is recommended at baseline and during follow-up 1.
From the Research
Antibodies Positive in SLE
- Antinuclear antibodies (ANA) are often tested as a screening tool in patients with suspected systemic lupus erythematosus (SLE) or connective tissue diseases 2
- Anti-double stranded DNA (anti-dsDNA) antibodies are also commonly used in the diagnosis of SLE 2, 3, 4, 5
- Anti-nucleosome antibodies (anti-nuc) have been shown to be a useful diagnostic marker for SLE, with high sensitivity and specificity 3, 5
- Other autoantibodies, such as anti-Sm and anti-histone antibodies, may also be present in patients with SLE 3, 4
Diagnostic Markers
- ANA positivity is an important element in the classification of patients with SLE, with a sensitivity of 98% and specificity of 92% at a titer of ≥1:80 2
- Anti-dsDNA antibodies have a specificity of 100% and 97% when using sera from healthy controls and patients with multiple medical problems, respectively 2
- Anti-nuc antibodies have a sensitivity of 61% and specificity of 94%, with an odds ratio for having SLE of 40.7 5
- Anti-nuc antibodies may be a better diagnostic marker than anti-dsDNA antibodies for SLE, with higher sensitivity and prognostic value 5
Disease Activity and Autoantibodies
- Anti-nuc antibodies have been shown to be associated with disease activity in SLE, with a higher incidence of autoantibodies in patients with active disease 3
- Anti-dsDNA antibodies may also be associated with disease activity, but the relationship is not as clear-cut as with anti-nuc antibodies 3, 5
- The presence of autoantibodies, such as ANA and anti-dsDNA, can be useful in monitoring disease activity and response to treatment in patients with SLE 2, 3, 4