​What is Pathology - How does the complement system work?

​What is Pathology - How does the complement system work?
​The classical, alternative, and lectin-binding pathways are three convergent methods that can activate the complement system. 
a) Classical pathway: This was termed after the discovery of the pathway during the development of antigen–antibody immune complexes many years ago. 
b) Alternative pathway: Foreign chemicals, poisons, and enzymes, as well as pieces of bacteria and fungi, activate this pathway. 
c) The mannose-binding protein (MBP), a liver-derived plasma protein, initiates the lectin-binding pathway. MBP binds to mannose residues on the bacterial plasma membrane and is a key player in the bacterial inflammatory response.