What is CDC and why would you need it?
What is Complement-Dependent Cytotoxicity?
Complement-Dependent Cytotoxicity (CDC) is a form of cytotoxicity mediated by the host organism’s complement system. Components of the complement system become activated by three main mechanisms and all pathways lead to the formation of the membrane attack complex (MAC) on a target cell or organism. This MAC creates an opening in the plasma membrane of the cell or organism to drive death by osmotic lysis.
What is the complement system and what are its associated pathways?
A host organism’s complement system consists of over 30 proteins, including cell membrane receptors, serosal proteins, and serum proteins. These proteins are inactive until a trigger is received, whereupon complement proteins are cleaved into their active forms to initiate a cascade of complement protein cleavages. This cascade of cleavages results in the formation of the MAC, which creates openings in the plasma membrane of the target cell to promote death by osmotic lysis. Furthermore, activation of the complement system leads to the release of cytokines that promote immune cell homing and activation.
There are three main pathways associated with complement system activation. The first is the classical pathway (Figure 1), which is mediated by IgM or IgG antibodies complexed with cell surface antigens and C1q of the complement system. Formation of the antibody/antigen complex recruits C1q to the target cell/pathogen and promotes the formation of the C1 complex. The establishment of this complex on the foreign cell initiates a protein cleavage cascade that results in MAC formation on the target cell and its eventual lysis.