More than 90% Rheumatoid arthritis patients have autoantibodies which recognise proteins in which arginine residues have been modified to citrulline. This process may well be the cause of the inflammatory process since citrullinated proteins and the enzymes responsible for producing them are found in inmflamed synovium. These antibodies are detected in the laboratory using artificial cyclic citrulline peptides (anti-CCP Ab).This assay is far more sensitive and specific than rheumatoid factor for the diagnosis of rheumatoid arthritis and some childhood arthritides. However the 2009 NICE guidelines (bizarrely) recommend the continued use of rheumatoid factor based on cost effectiveness.
More sensitive and more specific than rheumatoid factor for diagnosis of rheumatoid arthritis and some juvenile arthritides.
Positive anti-CCP in adults is almost certainly associated with rheumatoid arthritis though the autoantibody can appear before clear clinical signs. A small minority of RA patients do not have anti-CCP antibodies though with development of each new generation of the test, this number falls.
Serum Separator Tube (SST)
Fluorescence enzyme linked immunoassay (Phadia Immunocap 250): Synthetic citrullinated peptides second generation: IgG antibodies.
Assay range notes
Negative = <7U/mL
Equivocal = 7-10U/mL
Positive = >10U/mL
Assay Range 0.4 to >340U/ml
3 – 5 days
Immunology The James Cook University Hospital