Cyclic citrullinated peptide (CCP) antibodies
CCP antibodies are directed against peptides containing the amino acid citrulline, a post-translationally modified form of arginine. The dysregulation of citrullinating enzymes (peptidylarginine deiminases, PADs) is a feature of rheumatoid arthritis (RA) and citrullinated proteins are major targets of antibodies in these patients. CCP antibodies may precede clinical disease and they predict the eventual development of undifferentiated arthritis into RA, they are also a marker of erosive joint disease in RA. CCP antibodies may also be seen in other autoimmune connective tissue diseases (e.g. SLE).
Both RF and CCP have moderate sensitivity for RA (50-60%) and therefore a negative test does not exclude disease. Weakly positive results may have little significance and the likelihood ratio for RA increases as CCP and RF levels increase (https://doi:10.1136/rmdopen-2021-002099). CCP antibodies are more specific for both early and established RA compared to rheumatoid factor (RF) antibodies. Both antibodies are included in the ACR/EULAR 2010 classification criteria for RA (https://doi.org/10.1093/rheumatology/kes279).
This assay is performed by chemiluminescent microparticle immunoassay.
Differential diagnosis of inflammatory arthritis
<5 AU/mL (range derived by the manufacturer and verified in house)
|Sample & container required
|Serum (SST gold top)
|5-10 mL blood (1 mL serum)