The C1q binding activity of IgG is modified in vitro by reactive oxygen species: implications for rheumatoid arthritis.
IgG can be denatured in vitro by reactive oxygen species (ROS). Native IgG activates the complement cascade through C1q. Using a modified ELISA, C1q binding activity of rheumatoid IgG has been compared to IgG denatured by neutrophil-derived ROS. The C1q binding activity of rheumatoid synovial fluid IgG is greater than the corresponding serum IgG (P < 0.01). Denaturation of IgG by activated polymorphs or the Fenton reaction decreased its C1q binding activity (P < 0.01). In vitro exposure of IgG to OH. and ROO. increased its interaction with C1q (P < 0.01). Hypochlorous acid had no effect. ROS-induced alteration to IgG-C1q binding activity may promote the inflammatory response in rheumatoid arthritis.
Griffiths
H R
HR
Division of Chemical Pathology, Hodgkin Building, Leicester, UK.
Lunec
J
J
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000276:immunology*; D003167:Complement Activation; D015922:Complement C1q / Q000378:metabolism* / Q000528:radiation effects; D003300:Copper; D005720:Gamma Rays; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D006997:Hypochlorous Acid / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism* / Q000528:radiation effects; D008875:Middle Aged; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D013582:Synovial Fluid / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007074:Immunoglobulin G; D017382:Reactive Oxygen Species; D013481:Superoxides; D006997:Hypochlorous Acid; D003300:Copper; D015922:Complement C1q; D006861:Hydrogen Peroxide; D013755:Tetradecanoylphorbol Acetate