The Terminal Complement Complex (TCC), also known as the Membrane Attack Complex (MAC), is a collection of secreted proteins that play a critical role in the immune response, specifically in the process of eliminating foreign substances and pathogens from the body. It is the final step in the activation of the complement system, which is a component of the innate immune system.
The TCC is composed of several complement proteins that work together to form a pore-like structure on the surface of target cells. These proteins include C5b, C6, C7, C8, and multiple copies of C9. The TCC assembles in a cascading fashion on the cell membrane, forming a transmembrane channel that disrupts the integrity of the target cell's plasma membrane.
Once formed, the TCC creates a permeable pore through which ions and molecules can freely flow into and out of the cell. This disrupts the cell's osmotic balance and causes cell lysis, leading to the destruction of the targeted cells, such as bacteria, viruses, or other pathogens. This process is particularly effective against microorganisms with weak or absent protective layers, as the TCC can directly damage their lipid bilayers.
In addition to its role in host defense, dysregulation of the TCC can also be implicated in various diseases, including autoimmune disorders and inflammatory conditions. Thus, understanding the formation and regulation of the Terminal Complement Complex is crucial for developing targeted therapies and interventions for immune-related disorders.
