Complement System Antibodies and Proteins

Activation of Complement System Antibodies


The complement system as part of the innate immune response, not only has a significant role in the fight against infection but also in the development of autoimmune disease. The primary function of the complement system is the lysis of cells, bacteria, viruses, and initiation of phagocytosis by opsonization. In addition, the complement system also engages cells of immune system to trigger processes leading to inflammation.

Activation of complement is the result of a cascade of proteolytic steps involving three different pathways:

  • The classical or antibody dependent pathway - where activation is triggered by antibody-target interactions.
  • The alternative or antibody independent pathway - where activation occurs via recognition of foreign surface structures. This pathway also amplifies C3 activation triggered by the other two pathways.
  • The mannose binding-lectin (MBL) or lectin pathway - where activation is stimulated by pathogen associated molecular patterns (PAMPS).

All three pathways converge at C3, one of the key control points in the proteolytic cascade, leading to the formation of the membrane attack complex (MAC) and subsequent cell lysis. 


Key Complement System Markers

Bio-Rad has a continually evolving range of antibodies against components of the complement system and recombinant proteins which mimic key signalling molecules. These include: 

  • Targets to the classical, alternative and mannose binding-lectin pathways
  • Receptor and regulatory proteins

Antibodies are available against many key components and markers such as C4d, C1q, C3 and C-reactive protein.  For more information regarding C4d, a well-established indicator of classical complement activation and therefore a popular marker of antibody mediated renal and cardiac transplant rejections, read our article on complement component C4d and biomarkers of transplantation rejection.

Complement System Markers

    DescriptionSpecificityTargetFormatHostIsotypeClone Applications Citations Product Type Code Validation Types

    Other Related Complement markers

    In addition to C4d, Bio-Rad also offers a wide range of other anti-human markers for complement such as: