ANTIBODIES TO CYCLIC CITRULINATED PEPTIDE; CCP (IgG)

CLINICAL UTILITY:

Testing for antibodies to the cyclic citrullinated peptide (CCP) has recently become a clinically available diagnostic test for RA. The test is moderately sensitive (45-80%, depending on the cohort studied) and approximately 98% specific for the diagnosis of RA . Furthermore, the test is frequently positive early in the course of RA when the diagnosis may be uncertain. Presence of CCP antibodies is associated with development of erosive arthritis. Anti-CCP can be found in RA patients both with and without IgM rheumatoid factor. The role of CCP antibody testing in evaluation of RA patients remains uncertain, but it seems to be similar to but additive to the information provided by RF testing, with somewhat lower sensitivity, higher specificity, and similar prognostic value. Approximately 2/3 of children with juvenile rheumatoid arthritis of all types have been reported to develop antibodies to CCP, making anti-CCP measurement of potential value in diagnosis of rheumatoid factor-negative juvenile rheumatoid arthritis.

Intracellular citrullinated proteins have been described in the synovium of patients with rheumatoid arthritis. The biologic significance and mechanism for generation of antibodies to citrullinated proteins remains unclear, but could provide clues to the pathogenesis of RA.

METHOD DESCRIPTION:

Antibodies to cyclic citrulinated peptide ARE measured colorimetrically using a solid phase immunoenzymatic assay (“sandwich” technique).

REFERENCE RANGE:

Negative <20 Units; Weak Positive 20-39 Units; Moderate Positive 40-59 Units; Strong Positive >59 Units

SPECIMEN REQUIREMENTS:

The assay requires 1.0 ml of serum (minimum of 0.5 ml) collected in a red top tube and separated from the cells as soon as possible.