Question

Decay accelerating factor (DAF) on the surface of blood cells protects against complement-mediated damage by inhibiting C3 convertase specific. The RBC membrane also contains MIRL which has a similar protective effect by preventing C9 from polymerizing. What is the function of Decay accelerating factor (DAF) on the surface of blood cells?

1) Inhibiting C3 convertase specific
2) Preventing C9 from polymerizing
3) Protecting against complement-mediated damage
4) Promoting blood cell growth

Answer 1

The Decay accelerating factor (DAF) on the surface of blood cells inhibits C3 convertase to protect against complement-mediated damage, ensuring that the body's own cells are not targeted by the immune system. The correct option is c.

Step-by-step explanation:

The function of Decay accelerating factor (DAF) on the surface of blood cells is to protect against complement-mediated damage by inhibiting the activity of C3 convertase.

DAF disrupts the formation and stability of the C3/C5 convertase complexes of the complement system, thereby preventing the continuation of the complement cascade that would lead to cell lysis. This action is essential as it prevents the complement system from attacking the body's own cells, especially blood cells like red blood cells (RBCs).

Therefore, the correct option is c.