Membrane attack complex (MAC) is an important immune effector of the complement terminal pathway that is composed of complement components C5b, C6, C7, C8, and C9. MAC is the collective come-off of three complement pathways (classical, lectin, or alternative pathway) that penetrates the cell membranes of microbes to form cytotoxic pores. These pores disrupt the phospholipid bilayers of target cell membrane, or form hydrophilic transmembrane channels, leading to cell lysis and death.