The detection of anti-RNAP III antibodies is useful in the diagnosis of SSc and for the identification of patients at risk for developing progressive skin thickening and renal crisis. The prevalence of IgG RNAP III antibodies is from 3 - 58% in SSc patients.

Gold serum separator (SST) tube

Immediatley following collection, mix sample by gently inverting 5 times

1. Allow sample to clot for a minimum of 30 minutes
2. Spin within one (1) hour of collection
3. Transfer serum to a Transfer vial/tube with cap - 12mL (LabCorp), labelled as serum

Transfer vial/tube with cap - 12mL (LabCorp)

Red serum vial/tube - 5 mL

1. Allow sample to clot
2. Spin within one (1) hour of collection
3. Transfer serum to a Transfer vial/tube with cap - 12mL (LabCorp), labelled as serum

Refrigerated (preferred) - 14 days

Ambient - 7 days

Frozen - 60 days

Freeze/thaw cycles - stable x1

• Grossly hemolyzed
• Bacterial contamination
• Lipemic
• Icteric
• Non-serum specimen types

Enzyme immunoassay (EIA)

Autoantibodies to RNA Polymerase III antigen are found in 11% to 23% of patients with systemic sclerosis. Patients who are positive for RNA Polymerase III antibodies do not have any of the other antibodies typically found in systemic sclerosis patients such as centromere, Scl-70, or Pm/Scl antibodies. Thus, they are a separate serologic group. Numerous studies have shown that these patients have an increased risk of the diffuse cutaneous form of scleroderma, with high likelihood of skin involvement and hypertensive renal disease. Antibodies to several different types of RNA Polymerases are found in patients with systemic sclerosis. The recombinant immunodominant epitope of RNA Polymerase III can be used in ELISA with high specificity to detect RNA Polymerase III antibodies in patients with the diffuse cutaneous form of systemic sclerosis