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Oxygen radical induced alterations in polyclonal IgG
H R Griffiths1, J Lunec, C A Gee
1Department of Biochemistry, Selly Oak Hospital, Birmingham, England.
FEBS Letters
|March 28, 1988
Summary
Hydroxyl (OH) radicals cause immunoglobulin G (IgG) aggregation and fluorescence in rheumatoid arthritis. Superoxide radicals are inert, while peroxy radicals cause fluorescence without aggregation, suggesting OH and peroxy radicals may denature IgG in vivo.
Area of Science:
- Biochemistry
- Immunology
- Free Radical Chemistry
Background:
- Rheumatoid arthritis (RA) patients exhibit aggregated and fluorescent immunoglobulin G (IgG) in sera and synovial fluid.
- Oxygen-free radicals are suspected contributors to IgG denaturation in RA, but the specific radical species remain unidentified.
Purpose of the Study:
- To investigate the effects of different oxygen-free radicals on polyclonal IgG.
- To identify the specific radical species responsible for IgG aggregation and fluorescence.
Main Methods:
- Polyclonal IgG was exposed to radiolytically generated oxygen-free radicals (hydroxyl, superoxide, and peroxy radicals).
- Aggregation and fluorescence changes in IgG were monitored.
Main Results:
- Hydroxyl (OH) radicals induced both IgG aggregation and a new fluorescence (Ex 360 nm, Em 454 nm).
- Superoxide radical anions did not induce aggregation or fluorescence.
- Peroxy radicals induced autofluorescence but not aggregation.
Conclusions:
- The findings suggest that hydroxyl (OH) radicals are a primary cause of IgG aggregation and fluorescence.
- Peroxy radicals may contribute to IgG autofluorescence.
- OH and/or peroxy radical attack represents a potential in vivo mechanism for IgG denaturation in rheumatoid arthritis.