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06:29
Methods for Quantitative Detection of Antibody-induced Complement Activation on Red Blood Cells
Published on: January 29, 2014
Recombinant C345C and factor I modules of complement components C5 and C7 inhibit C7 incorporation into the
Chuong-Thu Thai1, Ronald T Ogata
1Torrey Pines Institute for Molecular Studies, San Diego, CA 92121, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|May 10, 2005
Summary
The C5 C345C domain and C7 FIMs interaction is crucial for membrane attack complex (MAC) formation and complement-mediated lysis. This study demonstrates their essential role in these key complement system functions.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- Complement component C5 interacts with C6 and C7 through reversible reactions.
- The C5 C345C domain (NTR) mediates these reversible interactions.
- The C345C domain of C5 is suggested to be essential for membrane attack complex (MAC) assembly.
Purpose of the Study:
- To investigate the role of the C5 C345C domain and C7 factor I modules (FIMs) in MAC formation.
- To analyze the interaction between C5 and C7 during MAC assembly using surface plasmon resonance.
- To determine the impact of this interaction on complement-mediated erythrocyte lysis.
Main Methods:
- Developed a novel method using surface plasmon resonance to assemble MAC-like complexes.
- Monitored the incorporation of C7, C8, and C9 into the complex.
- Assessed the inhibitory effects of recombinant C5 C345C (rC5-C345C) and C7 FIMs (rC7-FIMs) on MAC formation and complement lysis.
Main Results:
- C7 binds to surface-bound C5b,6 with a dissociation constant (Kd) of approximately 3 pM.
- Micromolar concentrations of rC5-C345C or rC7-FIMs inhibited C7 binding to C5b,6, thus inhibiting early MAC formation.
- Both rC5-C345C and rC7-FIMs inhibited complement-mediated erythrocyte lysis via reactive lysis and classical pathways.
Conclusions:
- The interaction between the C5 C345C domain and C7 FIMs is essential for MAC formation.
- This interaction plays a critical role in the lytic activity of the complement system.
- Targeting this interaction could modulate complement-mediated inflammatory and lytic responses.
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