ANA Elevation in Psoriasis
Antinuclear antibodies (ANA) are not characteristically elevated in untreated psoriasis patients, with only approximately 5-6% showing any positivity at low titers (typically 1:40-1:80), which has minimal clinical significance. 1, 2
Baseline ANA Status in Psoriasis
- In untreated psoriasis patients, ANA positivity occurs in only 5.7% of cases, with titers typically ranging from 1:80 to 1:640 1
- When positive, the most common patterns are homogeneous (3 cases) and speckled (2 cases), with no peripheral patterns observed 1
- Anti-dsDNA antibodies are generally negative in psoriasis patients without treatment 1, 2
- Other autoantibodies (anti-SSA, anti-SSB, anti-Scl-70, anti-Jo-1) are not positive in psoriasis vulgaris 2
- A 1:40-1:80 ANA titer occurs in 31.7% of healthy individuals and has very limited diagnostic value, with only 74.7% specificity for autoimmune disease 3
Effect of Biologic Treatment on ANA Status
If the patient is receiving TNF inhibitor therapy, ANA positivity becomes much more common (21-38.7% of patients), but this rarely causes clinical autoimmune disease. 4, 5, 6
- During infliximab treatment, median ANA titers increase dramatically from 1:80 pretreatment to 1:1280 after 10 infusions and 1:1920 after 20 infusions 5
- Among biologic agents, infliximab causes ANA positivity most frequently (9 of 12 patients who developed ANA positivity), followed by etanercept (2 patients) and adalimumab (1 patient) 4
- The most common ANA patterns during biologic therapy are nuclear homogeneous, nuclear fine speckled, and nuclear large/coarse speckled 4
- Anti-dsDNA antibodies may develop during infliximab therapy but remain rare 4
- Despite ANA positivity, drug-induced lupus erythematosus or other autoimmune diseases do not typically develop 4, 6
Clinical Significance and Monitoring
- Higher pretreatment ANA titers and anti-dsDNA concentrations predict loss of response to infliximab and development of anti-infliximab antibodies 5
- Concomitant methotrexate use and phototherapy history do not affect ANA status during biologic therapy 4
- Baseline ANA and ENA measurement is recommended before starting TNF inhibitors, but routine serial measurements during follow-up are not necessary unless signs or symptoms of autoimmune disease develop 6
Psoriatic Arthritis Considerations
- Patients with psoriatic arthritis may have autoantibodies, but rheumatoid factor negativity is a key diagnostic criterion (CASPAR criteria) 7
- The presence of high-titer rheumatoid factor or rheumatoid nodules suggests rheumatoid arthritis rather than psoriatic arthritis 7
Common Pitfalls
- Do not pursue extensive autoimmune workup in asymptomatic psoriasis patients with low-titer ANA (1:40-1:80), as this represents a false-positive result in the majority of cases 3, 1
- Do not discontinue effective biologic therapy solely based on ANA positivity without clinical evidence of autoimmune disease 4, 6
- Avoid confusing coincidental psoriasis in patients with systemic lupus erythematosus (rare coexistence) with ANA positivity induced by psoriasis treatment 1