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C-reactive protein-mediated complement activation in polymyalgia rheumatica and other systemic inflammatory diseases
P Vaith1, G M Hänsch, H H Peter
1Department of Rheumatology and Clinical Immunology, Medical University Clinic, Freiburg, Federal Republic of Germany.
Rheumatology International
|January 1, 1988
Summary
A new test detects complement deposition in kidney structures, aiding in diagnosing inflammatory diseases like polymyalgia rheumatica (PMR). This C4-C3-IFT method, while sensitive for PMR, also shows reactivity in other inflammatory conditions, highlighting C-reactive protein
Area of Science:
- Immunology
- Nephrology
- Pathology
Background:
- Complement (C) components C4 and C3 can deposit independently of immunoglobulins.
- This deposition occurs on rat kidney medullary structures in patients with inflammatory diseases.
- A novel indirect immunofluorescence test (C4-C3-IFT) has been developed to detect this phenomenon.
Purpose of the Study:
- To evaluate the diagnostic value of C4-C3-IFT for polymyalgia rheumatica (PMR).
- To investigate the specificity of C4-C3-IFT for PMR versus other systemic inflammatory diseases.
- To elucidate the underlying mechanisms of C4-C3 deposition, particularly the role of C-reactive protein (CRP).
Main Methods:
- Indirect immunofluorescence (IFT) was used to detect C4 and C3 deposition on rat kidney medullary structures.
- Sera from patients with active PMR and other systemic inflammatory diseases were analyzed.
- Experimental studies were conducted to investigate the interaction between CRP and complement components.
Main Results:
- All sera from patients with active PMR showed positive C4-C3-IFT reactions.
- Positive C4-C3-IFT reactions were also observed in systemic inflammatory diseases other than PMR, indicating limited specificity.
- Experimental data suggest that CRP binds to rat kidney structures, activating the classical complement cascade and leading to C4 and C3 fixation.
Conclusions:
- C4-C3-IFT is a sensitive diagnostic marker for active polymyalgia rheumatica.
- The test is not specific for PMR and can be positive in other inflammatory conditions.
- C4-C3-IFT detects CRP-mediated complement activation, offering a simple method to screen for this process and potentially understand CRP's role in inflammation.