Basic components of the immune system part 72

Once these components are activated, that is,C3b, 4b2b or C3bBb, and properdin, these molecules trigger sequentially C5,C6,C7, C8 and C9, which leads to the final lytic pathway and lysis of the target cell. The target can be a red cell, a virally infected cell, or a bacterium. Electron microscopy has shown that this complex binds to cell membrane and actually punches a hole  in the cell. Salts and water pass through the hole and the water fills the cell, eventually leading to swelling and destruction of the cell.