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Effect of polymorph derived oxidants on IgG in relation to rheumatoid factor binding
1Department of Biochemistry, Selly Oak Hospital, Birmingham, UK.
Scandinavian Journal of Rheumatology. Supplement
|January 1, 1988
Summary
Oxygen radicals denature Immunoglobulin G (IgG) in rheumatoid arthritis patients, creating antigens that bind to rheumatoid factors (RF). This explains autoantibodies to IgG in rheumatoid arthritis.
Area of Science:
- Rheumatology
- Immunology
- Biochemistry
Background:
- Immunoglobulin G (IgG) denaturation in rheumatoid arthritis (RA) may explain autoantibodies to IgG.
- Oxygen radicals (OR) from activated polymorphs are implicated in IgG denaturation in vivo.
Purpose of the Study:
- To investigate if polyclonal rheumatoid factors (RF) bind to OR-denatured IgG.
- To determine the role of OR in IgG denaturation and RF binding in rheumatoid arthritis.
Main Methods:
- Modified ELISA technique using sera from rheumatoid patients and controls.
- In vitro generation of OR using activated polymorphs (PMNs), radiolysis, and myeloperoxidase system.
- Assessing binding of IgA and IgM RF to denatured IgG.
Main Results:
- IgA and IgM RF binding to PMN-denatured IgG increased dose-dependently in seropositive rheumatoid arthritis sera.
- Hydroxyl radicals (OH·), but not superoxide radicals, significantly increased RF binding in seropositive sera.
- Myeloperoxidase system and elastase-treated IgG did not enhance RF binding.
Conclusions:
- IgG is denatured by OR released from activated PMNs, generating an antigen for polyclonal RFs.
- OR-induced IgG denaturation contributes to the autoimmune response in rheumatoid arthritis.