[Binding and activation of the first component of human complement on artificial matrices]

Area of Science:

• Biomaterials Science
• Immunochemistry
• Complement System Biology

Context:

• The complement system is crucial for innate immunity and its dysregulation is implicated in various diseases.
• Isolation and purification of complement proteins, like C1q, are essential for research and therapeutic development.
• Current methods for C1q isolation can be complex and may yield limited quantities.

Purpose:

• To synthesize and characterize novel artificial sorbent materials for C1q binding.
• To evaluate the binding affinity and specificity of C1q to the synthesized sorbents.
• To develop an efficient method for C1q isolation from human serum using affinity chromatography.

Summary:

• Artificial sorbents were created using macroporous glass functionalized with N-vinylpyrrolidone copolymers.
• One sorbent (IgG-glass) was functionalized with immunoglobulin G (IgG) via a hexamethylenediamine spacer, showing specific binding to C1q with a high affinity constant (Ka = 4.07 x 10^7 M-1).
• Binding of C1q to IgG-glass demonstrated a higher free energy than to monomeric IgG, indicating a multivalent interaction where one C1q molecule binds to two IgG molecules. Nonspecific binding of C1q to AE-glass (aminoethanol-functionalized) was minimal.
• Both specific and nonspecific binding of C1q to the sorbents activated the classical complement pathway, evidenced by the consumption of C4, C2, C3, and C5.
• The IgG-glass sorbent was successfully employed for C1q isolation from human serum via affinity chromatography, achieving a high yield of 63.6% for purified C1q after subsequent gel filtration.

Impact:

• This study presents a novel and efficient method for the purification of C1q, a key initiator of the classical complement pathway.
• The developed IgG-glass affinity chromatography offers a high yield and purity of C1q, facilitating further research into its functions and therapeutic applications.
• The ability to activate complement pathways via these sorbents opens possibilities for developing diagnostic tools or immunomodulatory agents.