Using the anti-mouse citrullinated collagen type II antibody as a biomarker for RA.
The citrullination of proteins is a post-translational modification where peptidyl arginine residues are converted to peptidyl citrulline by a family of enzymes called peptidyl arginine deiminases (PADs). Citrullination can be found in multiple tissue types and has been shown to occur in both human and mouse inflamed joints (1,2, 3). Proteins are susceptible to citrullination during inflammatory processes and an autoantibody response to citrullinated proteins is a hallmark of Rheumatoid Arthritis (RA). Antibodies against citrullinated proteins (ACPAs) can be found in 50-70% of all RA patients and have a high diagnostic value as a biomarker for detecting RA early (4,5). Present studies are focused on understanding the detailed mechanisms causing direct inflammation of the joints and the self-perpetuating behavior of RA, via the recognition of post-translation modifications such as citrullination by T and B cells.
Citrullinated antibody applications:
The mouse monoclonal antibody to citrullinated collagen type II (CII) can be used for the immunohistological analysis of citrullinated CII at different stages of experimental arthritis. The antibody has been used on arthritic animal tissue sections obtained from joints, cartilage and the synovial tissue. The presence of citrullinated CII correlates with the degree of inflammation.
The antibody can also be used as the detecting antibody in a Capture ELISA for citrullinated CII found in synovial fluid sampled from knee joints of RA patients. In this case, the ELISA plate wells would be coated with an antibody specific to collagen type II, synovial fluid would be used as your sample and the citrullinated CII antibody would be used with a colorimetric reagent for detection.
| Product | Specificity |
| Citrullinated Collagen Type II, clone ACC-1 | The C1 epitope containes 2 arginines which can be postranslationally converted to citrulline. This antibody will recognize the 2nd citrulline at position 365. Cross-reactivity is exhibited with denatured CII as well as denatured C1 epitope. |
| Citrullinated Collagen Type II, clone ACC-4 | The C1 epitope containes 2 arginines which can be postranslationally converted to citrulline. This antibody will recognize the 1st citrulline at position 360. Slight cross-reactivity is exhibited with cyclic citrullinated filaggrin peptide (i.e. CCP1). |
References:
1) Vossenaar ER, et al. 2003. Citrullination of synovial proteins in murine models of rheumatoid arthritis. Arthritis Rheum. 48:2489-2500.
2) Baeten D, et al. 2001. Specific presence of intracellular citrullinated proteins in rheumatoid arthritis synovium: relevance to antifilagrin autoantibodies. Arthritis Rheum. 44:2255-2262.
3) Foulquier C, et al. 2007. Peptidyl arginine deiminase type 2 (PAD-2) and PAD-4 but not PAD-1, PAD-3, and PAD-6 are expressed in rheumatoid arthritis synovium in close association with tissue inflammation. Arthritis Rheum. 56:3541-3553.
4) Mason-Bessiere C, et al. 2000. In the rheumatoid pannus, anti-filaggrin autoantibodies are produced by local plasma cells and constitute a higher proportion of IgG than in synovial fluid and serum. Clin. Exp. Immunol. 119:544-552.
5) Caspi D, et al. 2006. Synovial fluid levels of anti-cyclic citrullinated peptides antibodies and IgA rheumatoid factor in rheumatoid arthritis, psoriatic arthritis, and osteoarthritis. Arthritis Rheum. 55:53-56.
6) Usal H, et al. 2008. Structure and pathogenicity of antibodies specific for citrullinated collagen type II in experimental arthritis. J. Exp. Med. 206:449-462.