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Immunoreactants in rheumatoid synovial effusions.
1Department of Medicine, University of California at San Diego, School of Medicine, La Jolla, California 92037.
The Journal of Experimental Medicine
|October 30, 2009
Summary
Local production of immunoglobulin G (IgG) in rheumatoid synovium contributes significantly to joint inflammation. This local IgG synthesis, along with immune cell migration factors, highlights the complex immune mechanisms in rheumatoid arthritis.
Area of Science:
- Immunology
- Rheumatology
- Biochemistry
Background:
- Rheumatoid arthritis (RA) involves significant inflammation within the synovial joint.
- The role of locally produced immunoglobulins and immune cell migration in RA pathogenesis requires further elucidation.
Purpose of the Study:
- To quantify local immunoglobulin G (IgG) production by the rheumatoid synovium.
- To investigate the presence and nature of chemotactic factors in rheumatoid synovial fluid responsible for white blood cell migration.
Main Methods:
- Measurement of IgG levels in synovial fluid from rheumatoid arthritis patients.
- Analysis of synovial fluid for factors inducing polymorphonuclear leukocyte (PMN) migration.
- Utilized physical-chemical techniques to identify chemotactic components.
Main Results:
- 12-24% of synovial fluid IgG in rheumatoid subjects originated from local synovium production.
- Significant IgG production (up to 95 mg/day/knee) was estimated in rheumatoid joints.
- Chemotactic activity in rheumatoid effusions was linked to complement components C5 and C6, specifically C 567 and C5a.
- An enzyme generating chemotactic activity from C5 was found in over half of rheumatoid fluids.
Conclusions:
- Local IgG synthesis by the synovium is a key feature of rheumatoid joint inflammation.
- Rheumatoid inflammation is characterized by significant immune cell infiltration driven by complement-derived chemotactic factors.
- These findings support the concept of RA as an immune complex disease with substantial local immunoreactant production.
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