Cyclic citrulline peptide antibody (CCP-Ak, anti-CCPAnti citrullinated peptide/protein antibodies, hence ACPA for short) is an antibody that can be used for the diagnosis of rheumatic diseases. The rheumatic form circle or collagenoses include:
- Dermatomyositis – disease belonging to the collagenoses, which affects the skin and muscles and is associated primarily with diffuse movement pain.
- Cryoglobulinemia – chronic recurrent immune complex vasculitides (immune disease of the vessels) characterized by the detection of abnormal cold precipitating serum proteins (cold antibodies).
- Lupus erythematosus – systemic disease affecting the skin and connective tissue of the vessels, leading to vasculitides (vascular inflammation) of numerous organs such as the heart, kidneys or brain.
- Mixed connective tissue disease – chronic inflammatory connective tissue disease in which symptoms of different collagenoses (systemic lupus erythematosus, scleroderma, polymyositis, Raynaud’s syndrome) occur.
- Panarteritis nodosa – necrotizing vasculitis that usually affects medium-sized vessels; in this case, the inflammation involves all wall layers (pan = Greek all; arteri- from artery = arteries; -itis = inflammatory).
- Polymyositis – is classified as a collagenosis; it is a systemic inflammatory disease of skeletal muscle with perivascular lymphocytic infiltration.
- Progressive systemic sclerosis (systemic sclerosis) – see scleroderma.
- Rheumatoid arthritis – chronic inflammatory multisystem disease that usually manifests as synovitis (inflammation of the synovial membrane). It is also called primary chronic polyarthritis (PcP).
- Sharp syndrome – chronic inflammatory connective tissue disease that includes symptoms of several collagenoses such as lupus erythematosus, scleroderma or polymyositis.
- Scleroderma (sclero = hard, dermia = skin) – rare autoimmune disease associated with connective tissue hardening of the skin alone or of the skin and internal organs (especially the digestive tract, lungs, heart, and kidneys)
- Sjögren’s syndrome (group of sicca syndromes) – autoimmune disease from the group of collagenoses leading to a chronic inflammatory disease of the exocrine glands, most commonly the salivary and lacrimal glands; typical sequelae or complications of sicca syndrome are:
- Keratoconjunctivitis sicca (dry eye syndrome) due to lack of wetting of the cornea and conjunctiva with tear fluid.
- Increased susceptibility to caries due to xerostomia (dry mouth) due to reduced salivary secretion.
- Rhinitis sicca (dry nasal mucous membranes), hoarseness and chronic cough irritation and impaired sexual function due to disruption of mucous gland production of the respiratory tract and genital organs.
The CCP-AK shows a higher specificity (probability that actually healthy people who do not suffer from the disease in question are also detected as healthy in the test: about 96%) in the diagnosis of rheumatoid arthritis compared to the rheumatoid factor (60-80%). CCP-AK are already 79% detectable in early stages of the disease: patients who detect CCP-AK in addition to rheumatoid factor tend to have a more severe disease course.
The procedure
Material needed
- Blood serum
Preparation of the patient
- Not necessary
Disruptive factors
- Not known
Normal value
| Normal value | 1: < 25 U/ml |
Indications
- Suspicion of diseases of the rheumatic system.
Interpretation
Interpretation of lowered values
- Not relevant to disease
Interpretation of elevated values
- Rheumatoid arthritis or other diseases of the rheumatoid type.
Further notes
- As a basic diagnostic test, the following laboratory tests should be performed when rheumatoid arthritis is suspected.
- CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate).
- Rheumatoid factor (or CCP-AK)
- ANA (antinuclear antibodies)
- HLA-B27 (histocompatibility antigens).
