Anti-Centromere Antibodies
Also known as: ACA
What Does Anti-Centromere Antibodies Measure?
Anti-Centromere Antibodies (ACA) are autoantibodies that target proteins found in the centromere region of chromosomes — the central structure that helps chromosomes separate correctly during cell division. Specifically, these antibodies most commonly react against centromere proteins CENP-A, CENP-B, and CENP-C. A blood test for ACA detects whether your immune system has mistakenly produced antibodies against these essential cellular components.
Why Does Anti-Centromere Antibodies Matter?
ACA are clinically significant because they serve as a highly specific biomarker for a subtype of systemic sclerosis (scleroderma) known as limited cutaneous systemic sclerosis (lcSSc), formerly called CREST syndrome (Calcinosis, Raynaud's phenomenon, Esophageal dysmotility, Sclerodactyly, and Telangiectasia). The presence of ACA helps physicians differentiate between subtypes of systemic sclerosis, guides prognosis, and informs treatment planning. Patients with ACA-positive limited scleroderma generally have a slower disease progression than those with diffuse scleroderma, but they remain at elevated risk for pulmonary arterial hypertension and ischemic complications. ACA can also occasionally appear in primary biliary cholangitis (PBC) and other autoimmune conditions.
Normal Ranges
Males
Negative (titer < 1:40 or antibody index < 1.0 U/mL; laboratory-specific reference ranges apply)
Females
Negative (titer < 1:40 or antibody index < 1.0 U/mL; laboratory-specific reference ranges apply)
Children
Negative; rarely tested in children outside specialized rheumatology contexts
Causes of High Levels
- Limited cutaneous systemic sclerosis (lcSSc / CREST syndrome) — the most common and specific cause
- Diffuse cutaneous systemic sclerosis — less frequently associated but can occur
- Primary biliary cholangitis (PBC) — ACA found in approximately 10–30% of PBC patients
- Raynaud's phenomenon (primary or secondary) — ACA positivity predicts progression to systemic sclerosis
- Overlap autoimmune syndromes — such as mixed connective tissue disease or Sjögren's syndrome with scleroderma features
- Drug-induced autoimmunity — rare cases linked to certain medications including procainamide and statins
Causes of Low Levels
- No underlying autoimmune condition — a negative result is the normal, healthy finding
- Effective immunosuppressive therapy — treatment may reduce detectable antibody titers in some patients
How to Improve Your Anti-Centromere Antibodies
Diet
- Adopt an anti-inflammatory diet rich in colorful vegetables, fruits, whole grains, and omega-3 fatty acids to support immune regulation
- Limit processed foods, refined sugars, and trans fats which can exacerbate systemic inflammation
- Maintain adequate antioxidant intake through foods like berries, leafy greens, and nuts to reduce oxidative stress associated with autoimmune activity
- Stay well-hydrated and consider a Mediterranean-style dietary pattern, which has shown benefits in autoimmune conditions
- For patients with esophageal involvement (CREST), eat smaller, more frequent meals and avoid lying down after eating to reduce reflux
Supplements
- Vitamin D3 (1,000–4,000 IU/day) — deficiency is common in autoimmune diseases and supplementation may help modulate immune function; check levels first
- Omega-3 fatty acids (fish oil, 2–4 g/day EPA+DHA) — may reduce systemic inflammation and support vascular health
- N-acetylcysteine (NAC, 600 mg twice daily) — antioxidant support that may help reduce oxidative stress in autoimmune conditions
- Magnesium (200–400 mg/day) — supports vascular smooth muscle relaxation, potentially beneficial for Raynaud's phenomenon
Related Biomarkers
Frequently Asked Questions
What does a positive anti-centromere antibody test mean?
A positive ACA result means your immune system is producing antibodies against proteins in your cell chromosomes. This is most commonly associated with limited cutaneous systemic sclerosis (also called CREST syndrome), a form of scleroderma. It can also occur in primary biliary cholangitis or as an early marker in people with Raynaud's phenomenon who may later develop scleroderma. A positive result alone does not confirm a diagnosis — your doctor will consider it alongside your symptoms, physical examination, and other laboratory findings.
Can you have a positive ACA test and be healthy?
Low-titer, weakly positive ACA results can occasionally occur in otherwise healthy individuals, particularly older adults, but this is uncommon. In most cases, a clearly positive ACA result (especially at higher titers) warrants a thorough evaluation by a rheumatologist. Some ACA-positive individuals may have very early or mild disease without obvious symptoms yet. Long-term monitoring is typically recommended even if no diagnosis is made immediately.
What is the difference between ACA and Anti-Scl-70 antibodies?
Both ACA and Anti-Scl-70 (anti-topoisomerase I) are autoantibodies associated with scleroderma, but they indicate different subtypes. ACA is predominantly associated with limited cutaneous systemic sclerosis (lcSSc/CREST syndrome), which typically involves skin changes limited to the hands, face, and forearms, and has a slower progression. Anti-Scl-70 is associated with diffuse cutaneous systemic sclerosis, which involves more widespread skin and internal organ involvement with a generally more aggressive course. The two antibodies are rarely found together in the same patient.