Complement membrane attack complex

The membrane attack complex (MAC) or terminal complement complex (TCC) is a structure typically formed on the surface of pathogenic bacterial cells as a result of the activation of the host's alternative pathway, classical pathway, or lectin pathway of the complement system, and it is one of the effector proteins of the immune system. The membrane-attack complex (MAC) forms transmembrane channels. These channels disrupt the cell membrane of target cells, leading to cell lysis and death.