RNA polymerase III antibodies target RNA polymerase epitopes 11 and 155 and are thus also known as anti-RP11 and anti-RP155.
These antibodies are found in 7% to 41% of patients with SSc and occur most often in dcSSc.
They are diagnostic for SSc, as they are rarely found in other autoimmune diseases, and are included in the 2013 ACR-EULAR classification criteria.
The presence of RNA polymerase III antibodies is associated with progressive skin thickening, gastric antral vascular ectasia (GAVE), and renal crisis.
In addition, these antibodies are associated with onset of cancer within a 2-year timeframe before or after onset of SSc skin changes. Historically, RNA polymerase III antibodies indicated a poor prognosis, but mortality rates improved after the introduction of ACE inhibitors to treat renal crisis; the prognosis for patients with RNA polymerase III antibodies is now better than for those with Scl-70 or U3-RNP antibodies.
Systemic Sclerosis Classification Criteria:
|
Classify as having systemic sclerosis if the sum of points for criteria below is ≥9. |
|
|
Criterion |
Points |
|
Skin thickened on fingers of both hands, extending proximal to the metacarpophalangeal joints |
9 |
|
Skin on fingers thickened (only count highest score) Puffy fingers Sclerodactylya |
2 4 |
|
Lesions on fingertips (only count highest score) Ulcers on tip of digits Pitting scars on fingertips |
2 3 |
|
Telangiectasia |
2 |
|
Abnormal nailfold capillaries |
2 |
|
Pulmonary arterial hypertension and/or interstitial lung disease (max score is 2) Pulmonary arterial hypertension Interstitial lung disease |
2 2 |
|
Raynaud phenomenon |
3 |
|
Presence of 1 or more of the following: Centromere antibody Scl-70 antibody RNA polymerase III antibody |
3 |
Clinical Characteristics Associated With Autoantibodies Used in the Diagnosis and Classification of Systemic Sclerosisa:
|
Antibody |
Prevalence in SSc, % |
Presence in other autoimmune diseases |
SSc type most likely |
Clinical associations |
Relative SSc prognosis |
|
ANA |
85-95 |
Common |
Does not help differentiate type |
Most common in rheumatic diseases |
Varies |
|
Centromere A or B |
20-40 b |
Uncommon |
lcSSc |
PAH, calcinosis, digital ischemia, intestinal involvement |
Better |
|
Ku |
1.5-5 |
Common |
Overlap syndromes or lcSSc |
Muscle and joint involvement |
Unclear |
|
PM/Scl-75 or PM/Scl-100 |
2-11 |
Common |
SSc-myositis overlap syndrome or lcSSc |
Muscle and joint involvement, calcinosis; GI and lung involvement for those with PM/Scl-75 |
Better |
|
RNA Polymerase III |
7-41 |
Rare |
dcSSc |
Renal crisis, progressive skin thickening, GAVE, malignancy |
Poorer |
|
Scl-70 |
9.4-71 b |
Rare |
dcSSc |
Severe pulmonary fibrosis, cardiac involvement, renal crisis, digital ulcers |
Poorer |
|
Th/To |
2-5 |
Rare |
lcSSc |
Pulmonary involvement |
Poorer |
|
U1-snRNP |
2-14 |
Common (90% in patients with MCTD) |
lcSSc |
PAH, arthritis, esophageal dysfunction |
Better |
|
U3-RNP (Fibrillarin) |
4-10 b |
Rare |
dcSSc |
Multiorgan involvement, PAH |
Poorer |
| ANA, antinuclear antibodies; dcSSc, diffuse cutaneous systemic sclerosis; GAVE, gastric antral vascular ectasia; GI, gastrointestinal; lcSSc, limited cutaneous systemic sclerosis; MCTD, mixed connective tissue disease; PAH, pulmonary arterial hypertension; SSc, systemic sclerosis. | |
| a | Data presented in this table have been compiled from the cited references. It is important to note that autoantibody frequency in SSc as well as other autoimmune diseases varies with sex, ethnicity, and population studied. |
| b | In the United States, prevalence has been shown to vary across ethnicities. |
References:
van den Hoogen F, Khanna D, Fransen J, et al. 2013 classification criteria for systemic sclerosis: an American College of Rheumatology/European League against Rheumatism collaborative initiative. Arthritis Rheum. 2013;65(11):2737-2747. doi:10.1002/art.38098
Stochmal A, Czuwara J, Trojanowska M, et al. Antinuclear antibodies in systemic sclerosis: an update. Clin Rev Allergy Immunol. 2020;58(1):40-51. doi:10.1007/s12016-018-8718-8
Hamaguchi Y, Takehara K. Anti-nuclear autoantibodies in systemic sclerosis: news and perspectives. J Scleroderma Relat Disord. 2018;3(3):201-213. doi:10.1177/2397198318783930
Shah AA, Hummers LK, Casciola-Rosen L, et al. Examination of autoantibody status and clinical features associated with cancer risk and cancer-associated scleroderma. Arthritis Rheumatol. 2015;67(4):1053-1061. doi:10.1002/art.39022
Sobanski V, Dauchet L, Lefèvre G, et al. Prevalence of anti-RNA polymerase III antibodies in systemic sclerosis: new data from a French cohort and a systematic review and meta-analysis. Arthritis Rheumatol. 2014;66(2):407-417. doi:10.1002/art.38219
RP155
Every lab result you’ve ever had, charted and explained.
Healthmatters is a tracker for your lab results. Upload a report from any lab, any country — every marker charted and explained.
Start with my report →
All our content is backed by peer-reviewed studies, academic research, and trusted medical sources. We’re committed to accuracy and transparency — see our editorial policy for details.