B cells express a complement receptor that binds to C3b cleavage products, such as iC3b and C3dg. When a B cell with an antigen receptor that specifically recognizes that pathogen also has its complement receptor stimulated because the pathogen is opsonized with these C3 fragments, B cell activation is greatly enhanced. Due to this mechanism, B cells can be activated by much lower concentrations of antigen (in this case, the pathogen) than if the antigen is devoid of complement components. This mechanism functions to:
A) Ensure that pathogens are readily detected by the adaptive immune system before they replicate to high levels in the host
B) Prevent B cells from being activated in response to antigens that are not pathogens
C) Allow B cells to phagocytose the pathogen and help destroy it
D) Induce increased rounds of B cell replication to make more pathogen-specific B cells
E) Allow the B cell to block pathogen replication by interfering with multiple pathogen surface functions

Question

Quizplus · Accepted Answer

The mechanism of B cell activation by complement fragments enhances the ability of the adaptive immune system to detect and respond to pathogens before they can replicate to high levels in the host. This ultimately helps to prevent the spread of infection and limit the damage caused by the pathogen.

B Cells Express a Complement Receptor That Binds to C3b