Which of the following complement components is an opsonin that binds to complement receptor 1 (CR1)on macrophages?

Question

Quizplus · Accepted Answer

C3b is an opsonin that binds to complement receptor 1 (CR1) on macrophages, enhancing phagocytosis of complement-coated pathogens by these cells. C3a is not an opsonin but a potent inflammatory mediator. Bb is a fragment of the alternative pathway C3 convertase, and Ba is a fragment of the alternative pathway C3/C5 convertase. C3bBb is the alternative pathway C3 convertase, not an opsonin that binds to CR1 on macrophages.

Which of the Following Complement Components Is an Opsonin That