Scl-70 Antibody

What is Scl-70 Antibody?

Detects antibodies against topoisomerase I, closely associated with diffuse systemic sclerosis and organ involvement.

Anti-Scl-70 antibodies, also called anti-topoisomerase I antibodies, target an enzyme involved in DNA structure and are one of the more disease-specific autoantibodies for systemic sclerosis (scleroderma). This marker relates to the immune system and connective tissues, including skin, blood vessels, and internal organs such as the lungs. Clinicians typically order Scl-70 testing, often as part of an ENA panel, in people with symptoms suggestive of scleroderma, such as skin thickening, Raynaud phenomenon, or unexplained shortness of breath, particularly when a positive ANA result has already been found. Because Scl-70 positivity has been associated in research with more extensive skin and lung involvement, it may help clinicians anticipate which body systems deserve closer monitoring. As with other autoantibodies, results are interpreted alongside clinical findings, imaging, and other laboratory tests rather than as a stand-alone diagnostic tool.

Tests often checked alongside this

• ANA (Antinuclear Antibody) — the broader screening test Scl-70 is typically reflexed from
• RNP Antibody — relevant when overlap with mixed connective tissue disease is considered
• Pulmonary function tests — often monitored together given lung involvement in scleroderma
• Complete blood count — helps assess overall health status

How this can show up in how you look and feel

• May be associated with skin thickening or tightness in some individuals
• May be associated with color changes in fingers or toes with cold exposure (Raynaud phenomenon)
• May be associated with shortness of breath or reduced exercise tolerance
• May be associated with digestive symptoms such as reflux in some cases

What can affect this marker

• Age
• Sex
• Inflammation
• Lab variability between testing methods

What to track over time

• Whether Scl-70 levels track alongside skin, lung, or vascular symptoms over time
• How this result fits with pulmonary function and imaging monitoring if ordered
• Repeat testing may be considered if new symptoms suggest disease progression

What to ask your doctor

• What does a positive Scl-70 result mean for monitoring my skin and lungs?
• Should I have pulmonary function testing given this result?
• How does this fit with my ANA and other ENA panel results?
• How often should this and related organ-system monitoring be repeated?

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