- Paper Report
- Open Access
Complement activation by CRP in RA
- Richard Brasington1
© Biomed Central Ltd 2001
- Received: 20 June 2001
- Published: 31 July 2001
- C-reactive protein
- rheumatoid arthritis
There is evidence that the complement system is involved in the pathogenesis of rheumatoid arthritis (RA). The serum and synovial fluid of RA patients contain complement activation products. Treatment of murine collagen-induced arthritis with a monoclonal antibody to C5 prevents the development of arthritis and attenuates established disease. A humanized form of this antibody has been shown to be effective in a phase II trial for treating RA.
The means by which complement becomes activated in RA are unclear. Immune complexes are present in the synovial fluid of patients with RA, although the evidence that these complexes are responsible for complement activation in RA is conflicting. As C-reactive protein (CRP) can activate complement (both in vivo and in vitro) the authors hypothesize that CRP activates the complement system in RA.
Serum levels of complexes of CRP and C3d (C3d-CRP) or C4d (CRP-C4d), were significantly higher in patients with active disease, and these levels correlated with the disease activity. Levels of activated C3 and C4 were also increased in patients with active RA. The authors conclude that CRP is partly responsible for the activation of the complement system in RA.
Measurement of complement, CRP, and complement activation products in serum samples; modified Disease Activity Score determination