Compliment system (1)

Question 1

What is the compliment system

Answer 1

Discovery of 30+ proteins which aid in phagocytosis

Question 2

What are the 3 pathways and what do they all produce

Answer 2

• Classic pathway
• Lectin pathway
• Alternative pathway
• All form C3 convertase

Question 3

Describe the classical pathway

Answer 3

• C1 binds to FC region of antigen
• C1 is activated and causes any nearby C2 and C4 to split in half
• 1 C2 and 1 C4 will bind to form C3 convertase

Question 4

Describe the lectin pathway

Answer 4

• Antibody binds to antigen
• Manose binding lectin will bind to the FC region of the antibody
• This actives manose binding lectin associated serine proteases which will cause any nearby C2 and C4 to break in half
• They join to form C3 convertase

Question 5

Describe the alternative pathway

Answer 5

• C3 binds to antibody
• C3 converts to C3 H2O
• C3 H2O Is then modified by factor B
• Whole molecule is sliced by factor D
• We now C3 convertase

Question 6

What occurs after these pathways

Answer 6

• C3 convertase will split in half to form C3a and C3b
• C3a calls other immune cells, C3b will either bind to the antigen and mark it for destruction or cause C5 to split into C5a and C5b
• C5b will bind to C6, C7, C8 or C9 on the cell and form the membrane attack complex