Complement System Antibodies

The complement system carries out a range of tasks as part of the innate immune response. Its primary function is the lysis of cells, bacteria, and viruses, and initiation of phagocytosis by opsonization. In addition, the complement system 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

Our range includes antibodies against several important complement cascade components, such as C4d (2222-8004, 0300-0230) which is an indicator of classical complement activation. C4d is also commonly used as a marker for antibody mediated renal and cardiac transplant rejections, and for kidney biopsies.

Other key complement components include: C1q, complement factor H, and human C3 (MCA2604, MCA2648) fragments and antigens.