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Methods for Quantitative Detection of Antibody-induced Complement Activation on Red Blood Cells
Published on: January 29, 2014
Polyanion-induced self-association of complement factor H
Michael K Pangburn1, Nenoo Rawal, Claudio Cortes
1Department of Biochemistry, Center for Biomedical Research, University of Texas Health Science Center, Tyler, TX 75708, USA. michael.pangburn@uthct.edu
Journal of Immunology (Baltimore, Md. : 1950)
|January 7, 2009
Summary
Factor H regulates complement activation by binding to host cells. Polyanion interaction induces Factor H self-association into dimers and tetramers, enhancing its regulatory functions.
Area of Science:
- Immunology
- Biochemistry
- Complement System
Background:
- Factor H is the main regulator of the alternative complement pathway.
- It prevents complement activation on host cells by binding to C3b and polyanions.
Purpose of the Study:
- To investigate the effect of polyanions on Factor H structure and function.
- To determine the mechanism of Factor H-mediated complement regulation.
Main Methods:
- Gel filtration chromatography to assess Factor H size.
- Analytical ultracentrifugation to determine Factor H molecular weight and oligomeric state.
- Assays for decay accelerating and cofactor activity.
Main Results:
- Polyanions induce Factor H self-association, forming dimers and tetramers.
- Factor H exhibits an apparent size of 330,000 Da monomerically and up to 1,400,000 Da in the presence of polyanions.
- Polyanion-induced self-association enhances Factor H's decay accelerating and cofactor activity.
Conclusions:
- Factor H self-association, mediated by its C-terminal polyanion binding site, is crucial for its regulatory function.
- The formation of Factor H dimers and tetramers is a key mechanism for recognizing and regulating complement activation on host cells.
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