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Complement Function/Activity Test

Complement function or activity test allows for the determination of whether the protein is present and whether it has normal functional activity. A wide range of assays are now available in Creative Biolabs, such as Hemolysis assays (CH50 or AH50), Elisa Assays (c3a, c5a, FH, FB, C5b-9 or others), Complement Inhibitor Validation (IC50)......

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Creative Biolabs is an innovative and ambitious company which delivers value-added services. We own brilliant antibody engineering platform, protease inhibitor platform, and drug discovery platform. We are fully equipped to partner with our clients who are doing or may have the desire to work on complement systems for drug discovery and validation.


Encoded by C2 gene in human, C2 helps regulate part of the immune system known as the complement system. The complement system consists of a group of proteins that function synergistically to eliminate the foreign invaders such as bacteria, virus, parasites, trigger inflammation, remove the debris of the cellular contents. The complement system is composed of three pathways - classical pathway, lectin pathway, and alternative pathway. For the classical pathway, C1 complex derived from the classical pathway is activated and cleave C4 and C2 to form the C3 convertase. C3 convertase triggers further activation of the pathway. Similarly, when the lectin pathway is initiated by the carbohydrate on the surface of the foreign invaders, C2 will be cleaved and activated by mannose-binding protein-associated serine protease (MASP).

C1qrs activates C4 and C2. C4b associates with C2a to form C4b2a, the C3 convertase of the classical pathway. C3 convertase cleaves C3 into C3a and C3b.

Fig.1 Complement activation and the formation of C4bC2a.


C2 is required for the formation of the C3 convertase. For the classical pathway, the C1 complex will be activated, when the foreign invaders are detected by the antibody. C1 complex further cleaves C4 and C2 into C4a, C4b, and C2a, C2b respectively. C2a is released into the fluid phase and binds C4b to form the C3 convertase in the presence of Mg2+. It is speculated that the cleavage of C2 results in a conformational change of C2b while the C2a fragment retains most of the original structure. Similarly, C2 is cleaved by mannose-binding protein-associated serine protease 2 (MASP2).

C2-related Disease

C2 deficiency is a disorder when the malfunction of the immune system is triggered, resulting in a form of immunodeficiency. Immunodeficiencies are conditions when the immune system is not able to protect the body effectively from foreign invaders such as bacteria and viruses. People with C2 deficiency are associated with systemic lupus erythematosus (SLE) and are susceptible to the risk of recurrent bacterial infections, specifically of the lungs (pneumonia), the inflammation of the membrane covering the brain and spinal cord (meningitis), and the blood (sepsis), which may be life-threatening.

Approximately 90% of people with complement component 2 deficiency have a mutation that removes nucleotides from the C2 gene. This mutation enables the prevention of C2 production. As C2 is essential to form C3 convertase, the activation of the complement system is stalled. Furthermore, the ability of the complement system to fight infections is diminished. The dysfunctional complement system is unable to distinguish the normal cells and invaders. It sometimes attacks normal tissues, leading to autoimmunity. Alternatively, the dysfunctional complement system may at times perform partial attacks on foreign invaders, which leaves behind foreign fragments and debris. The diminished complement system cannot distinguish from the body's tissues, so the complement system attacks the normal tissues, leading to disorders.

With professional knowledge and rich research experiences in drug discovery and complement therapeutic field, Creative Biolabs' outstanding research team are providing high-quality biotherapeutics development services based on the complement system. We offer turn-key or ala carte services customized to our client’s needs. If you are interested in our platform or you are calling for our services, please contact us for detailed information.

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