1. Multiple choice: Individuals with a genetic polymorphism in the Fc receptor,

Question

1. Multiple choice:
Individuals with a genetic polymorphism in the Fc receptor, FcRIIa (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 FcRIIa bind to the constant region of this receptor’s target antibody. The reason this FcRIIa-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.

2. Multiple choice: The W/Wv mouse strain is heterozygous for two different alleles of the gene encoding the growth factor receptor, c-kit, an important receptor expressed on hematopoietic progenitor cells in the bone marrow. The major defect in these mice is the absence of single lineage of hematopoietic cells. When these mice are challenged with larval Haemaphysalis longicorni sticks, they fail to become resistant to the ticks, in spite of generating high titers of anti-tick IgE antibodies. The cell type missing in the W/Wv mice is most likely:
A. Natural Killer (NK) cells
B. Eosinophils
C. Tissue-resident dendritic cells
D. Tissue-resident macrophages
E. Tissue-resident mast cells

3. True/False:
In some infectious diseases, antibodies specific for the pathogen are not essential for clearing a primary infection with that pathogen, but are essential in preventing re-infection by the same pathogen. This protective role of pathogen-specific antibodies is not useful for any
clinical applications.

Explanation / Answer

1) a

2)The cell type missing in the W/Wv mice is most likely: a - Natural Killer (NK) cells

3) true

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