Immunology Quiz

During the maturation of a B lymphocyte, the first immunoglobulin heavy chain synthesized is the

• Mu chain.

• gamma chain.

• epsilon chain.

• alpha chain.

A primary immune response in an adult human requires approximately how much time to produce detectable antibody levels in the blood?

• 12 hours

• 3 days

• 1 week

• 3 weeks

Antibody effector functions include all of the following EXCEPT

• activating complement on bacterial surfaces to promote phagocytosis by neutrophils.

• binding extracellular viruses to block their entry into host cells.

• binding intracellular viruses to initiate cytotoxicity.

• blocking uptake of bacterial toxins by host cells.

• coating bacteria to promote their phagocytosis by neutrophils.

Antigen-presenting cells that activate helper T cells must express which one of the following on their surfaces?

• IgE

• gamma interferon

• class I MHC antigens

• class II MHC antigens

Which one of the following substances is NOT released by activated helper T cells?

• interleukin-1

• gamma interferon

• interleukin-2

• interleukin-4

The alternative pathway of complement activation

• Properdin

• Factor D

• Factor B

• Microbial polysaccharide

• All of the above

The membrane IgM and IgD on the surface of an individual B cell

• have identical heavy chains but different light chains

• are identical except for their CH regions

• are identical except for their VH regions

• have different VH and VL regions

Which one of the following is NOT true of class I MHC antigens?

• They can be assayed by a cytotoxic test that uses antibody and complement.

• They can usually be identified in the laboratory in a few hours.

• They are controlled by at least three gene loci in the major histocompatibility complex.

• They are found mainly on B cells, macrophages, and activated T cells.

A woman had a high fever, hypotension, and a diffuse macular rash. When all cultures showed no bacterial growth, a diagnosis of toxic shock syndrome was made. Regarding the mechanism by which the toxin causes this disease, which one of the following is LEAST accurate?

• The toxin is not processed within the macrophage.

• The toxin binds to both the class II MHC protein and the T cell receptor.

• The toxin activates many CD4-positive T cells, and large amounts of interleukins are released.

• The toxin has an A-B subunit structure--the B subunit binds to a receptor, and the A subunit enters the cells and activates them.

If a person is born without C2 and C4,

• C5 can still be cleaved by the classical pathway.

• C3b will not be able to bind to bacteria.

• C9 will polymerize inappropriately and lyse host cells.

• the classical pathway will be changed into the alternative pathway.

• the amount of C3b produced during bacterial infections will be reduced.