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Complement System

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The complement system is a group of approximately 20 plasma proteins that strengthen the body's defenses against infections through opsonization, inflammation, and cell lysis. Opsonization involves coating pathogens with complement proteins, making them more recognizable and facilitating phagocyte engulfment. Certain complement proteins induce inflammation that attracts immune cells to the site of infection. Cell lysis involves the destruction of pathogens through the formation of a membrane...

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Covalent Binding of BMP-2 on Surfaces Using a Self-assembled Monolayer Approach

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Published on: August 26, 2013

Complement activation on surfaces carrying amino groups.

Mitsuaki Toda¹, Takayuki Kitazawa, Isao Hirata

¹Advanced Software Technology & Mechatronics Research Institute of Kyoto, 134 Minamimachi Chudoji, Shimogyo-ku, Kyoto 600-8813, Japan.

|October 24, 2007

Summary

Amino surfaces do not directly activate the complement system

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Area of Science:

Biomaterials science
Immunology
Surface chemistry

Background:

The complement system, crucial for innate immunity, can be activated by material surfaces.
Nucleophilic groups like hydroxyl (OH) and amino (NH2) on surfaces can influence complement activation.
Understanding material-based complement activation is vital for biomedical applications.

Purpose of the Study:

To investigate the complement activation potential of surfaces functionalized with amino groups.
To compare amino group-initiated complement activation with hydroxyl group-initiated activation.
To elucidate the role of amino groups in triggering the alternative and classical complement pathways.

Main Methods:

Utilized self-assembled monolayers (SAMs) of 11-amino-1-undecanethiol (NH2-SAM) and polyethyleneimine (PEI)-coated surfaces as amino-presenting models.
Employed SAMs of 11-mercaptoundecanol (OH-SAM) and 1-dodecanethiol (CH3-SAM) as controls.
Quantified complement protein C3b deposition and C3a fragment release from serum.

Main Results:

Amino surfaces showed significantly less C3b deposition compared to OH-SAM surfaces.
C3a release on amino surfaces was comparable to CH3-SAM and lower than OH-SAM.
No C1q deposition was observed on amino surfaces, suggesting no classical pathway activation.

Conclusions:

Nucleophilic amino groups on artificial surfaces do not directly activate the alternative complement pathway.
Adsorbed protein layers on amino surfaces contribute to complement activation, but to a lesser extent than on hydroxyl surfaces.
Amino surfaces appear to fail in activating the classical complement pathway, though further investigation is warranted.