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Updated: May 11, 2026
08:26
Measuring the 50% Haemolytic Complement (CH50) Activity of Serum
Published on: March 30, 2010
Circulating complement breakdown products in patients with rheumatoid arthritis. Correlation between plasma C3d,
The Journal of Clinical Investigation
|May 1, 1977
Summary
Complement activation, indicated by elevated C3d levels, is significantly present in rheumatoid arthritis (RA) patients. This finding correlates with disease activity and immune complexes, suggesting a role in RA pathogenesis.
Area of Science:
- Immunology
- Rheumatology
- Biochemistry
Background:
- Rheumatoid arthritis (RA) involves complex immune system dysregulation.
- Complement system activation is implicated in inflammatory joint diseases.
Purpose of the Study:
- To quantify C3d levels in RA patients to assess complement activation.
- To investigate the correlation between C3d, immune complexes, and RA disease activity.
Main Methods:
- Quantitative determination of C3d in plasma and synovial fluid samples from RA patients.
- Measurement of Clq binding activity (Clq BA) for circulating immune complexes.
- Correlation analysis of C3d levels with clinical disease activity indices.
Main Results:
- Significantly elevated plasma C3d levels in RA patients compared to controls.
- Higher C3d concentrations in synovial fluid than plasma in most RA patients.
- Strong correlation between plasma C3d, Clq BA, and RA disease activity metrics.
Conclusions:
- Complement activation, marked by increased C3d, is a feature of RA.
- Immune complexes likely drive complement activation in both circulation and joints.
- C3d levels serve as a potential biomarker for RA activity and pathogenesis.
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