Individuals with a Genetic Polymorphism in the Fc $\gamma$ Receptor, Fc $\gamma$

Multiple Choice

Individuals with a genetic polymorphism in the Fc $\gamma$ receptor, Fc $\gamma$ RIIa (CD32) , have an increased susceptibility to bacterial meningitis (inflammation of the membranes (meninges) surrounding the brain and spinal cord) caused by the encapsulated bacterium, Neisseria meningitidis. This polymorphism reduces the efficiency with which the phagocytes expressing Fc $\gamma$ RIIa bind to the constant region of this receptor's target antibody. The reason this Fc $\gamma$ RIIa-dependent response it the major form of protection against Neisseria meningitidis is because:

A) T cells are unable to enter the brain and spinal cord.
B) Mast cells are unable to localize to the meninges.
C) IgG antibodies are the major isotype able to diffuse into tissues.
D) IgM antibodies do not have high enough affinity to provide protection.
E) Neutrophils are unable to phagocytose encapsulated bacteria.