Question

1.Explain the events that take place during terminal pathway of the complement system.

2.In which way is the alternative pathway connected to both the classical and lectin pathway of the complement system?

3. How does the complement activated by the alternative pathway attacks pathogens while sparing host cells? Explain.

If someone can help me I'd greatly appreciate it. Thanks!

Answer 1

1. Terminal pathway of the complement system is initiated by proteins that bind to pathogen surfaces. As the process is initiated, triggered-enzyme cascade follows. Thereafter, C3 activation occurs on the surface of the pathogen and then covalent binding of C4b to the pathogen surface takes place. The cleavage of C4 exposes a highly reactive thioester bond on the C4b molecule that allows it to bind covalently to molecules in the immediate vicinity of its site of activation.

2. The alternative pathway is independent of pathogen-binding protein for its initiation as it is initiated through the spontaneous hydrolysis of C3.

3. The host cells are protected by complement regulatory proteins.