Anti-Ro Antibody

Anti-Ro antibodies, also known as anti-SSA antibodies, are associated with Sjögren syndrome.

Anti-Ro antibodies, immunoglobulin G (IgG) ^[1] :

• < 1 U (negative)
• ≥ 1 U (positive) 

A positive anti-Ro result is indicated by a speckled appearance under immunofluorescence with ultraviolet light.

Anti-Ro levels may be elevated in the following conditions: ^[1]

• Sjögren syndrome: 60-70% of cases

• Systemic lupus erythematosus (SLE): 25% of cases

Both anti-Ro/SSA and anti-La/SSB are usually absent in secondary Sjögren syndrome. ^[2]

When anti-Ro/SSA levels are elevated in SLE, it is often in antinuclear antibody (ANA)–negative lupus. ^[2]

Anti-Ro/SSA plus anti-La/SSB is associated with the following factors: ^[3]

• Age older than 50 years

• HLA-DR3

• Lower likelihood of anti-DNA antibodies

Anti-Ro/SSA without anti-La/SSB is associated with the following factors: ^[3]

• Age younger than 22 years

• HLA-DR2

• Worse renal manifestations

• Increased likelihood of anti-DNA antibodies

There are no special collection conditions or timings.

Draw in a standard red-top tube.

Hemolysis and lipemia should not affect the results but should be avoided, if possible.

There are no special storage conditions.

It is usually not part of a laboratory panel.

Description

Anti-Ro antibodies are associated with Sjögren syndrome.

Sjögren syndrome is often characterized by xerostomia and xerophthalmia-type symptoms. A diagnosis of Sjögren syndrome requires a minimum of 3 of the 4 following criteria: ^[4]

• Positive Schirmer test result or Rose Bengal score

• Histological grading of the minor salivary glands with a focus score of greater than 1

• Salivary flow of less than 1.5 mL in 15 minutes

• Anti-Ro/SSA and/or anti-La/SSB antibodies

At this time, no conclusive evidence indicates that any single laboratory technique provides superior sensitivities or specificities.

Indications/Applications

Anti-Ro, along with other autoantibody levels, should be obtained when a rheumatologic/connective tissue disorder is suspected, specifically if the following conditions manifest or are suspected: ^{[2, 3]}

• Photosensitivity or subacute cutaneous lupus

• Primary Sjögren syndrome vasculitis

• Cutaneous vasculitis/palpable purpura

• Interstitial lung disease

• Neonatal lupus

• Congenital heart block

• ANA-negative SLE

• Nephritis, vasculitis, lymphadenopathy, leukopenia

• Homozygous C2 and C4 deficiency with SLE-like disease

• Rheumatoid factor positivity and severe systemic symptoms

• SLE with interstitial pneumonitis