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HMX Immunology Final Exam: Questions & Answers
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HMX Immunology Final Exam: Questions & Answers
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HMX Immunology Final Exam: Questions & AnswersOne of the most important advances in surgery arrived near the end of the
nineteenth century. The British surgeon Joseph Lister hypothesized that using
techniques to sterilize surgical tools and clean the skin at the site of the
incision would reduce surgical site infections. Years later, Dr. Lister wrote
this:
"Nothing was formerly more striking in surgical experience than the
difference in the behavior of injuries according to whether the skin was
implicated or not. Thus, if the bones of the leg were broken and the skin
remained intact, the surgeon applied the necessary apparatus without any
other anxiety than that of maintaining a good position of the fragments,
although the internal injury to bones and soft parts might be very severe. If,
on the other hand, a wound of the skin was present, communicating with the
broken bones, although the damage might be in other respects comparatively
slight, the compound fractu Right Ans - Epithelial barriers
Which of the cells below are tissue resident sentinel cells Right Ans - mast
cell, macrophage, dendritic cell
Which of the cells below are circulating blood cells that will enter tissue in
response to inflammation? (select two answers) Right Ans - Neutrophils
Monoctyes
Mast cell Right Ans - Cells that release chemicals (such as histamine) that
promote inflammation.
Neutrophil Right Ans - Most abundant leukocyte
Phagocyte that rapidly dies after ingesting microbe
macrophage Right Ans - Phagocyte that cleans up apoptotic cells
When a monocyte moves into the tissues, it changes rapidly and becomes a
____________ . Right Ans - macrophage
Leukocyte adhesion deficiency (LAD) is a genetic defect that leads to
recurrent infections in the tissue and severe problems with wound healing.
,LAD patients also develop severe gingivitis (infections and inflammation of
the gums). In LAD, leukocyte migration into tissues is severely impaired. All of
these problems can be traced back to a genetic defect. Of the genetic defects
listed below, which is the most likely cause of LAD? Right Ans - A mutation
that introduces a stop codon into a gene that encodes part of the LFA-1
molecule (leading to a truncated protein).
Toll-like receptors for bacterial PAMPs are found on/in the Right Ans - cell
membrane
There are a few different proteins that act as inhibitors of NF-kB. There is a
very rare genetic disease in which one of these proteins, IkBα, is mutated. The
mutation substantially alters the stability of the IkBα protein. In patients with
this disease, IkBα protein expression does not change in response to stimuli
that cause IkBα degradation in healthy individuals. Consider the biological
role of NF-kB inhibitors. What are the most likely symptoms of this genetic
defect? Right Ans - Immunodeficiency with a susceptibility to bacterial
infections.
The complement pathway initiated by host proteins that bind to microbial
sugars is called the ____________ pathway. Right Ans - lectin pathway
ssRNA (single-stranded RNA) and dsDNA (double-stranded DNA) are present
in mammalian cells. Why don't our plasmacytoid dendritic cells activate an
innate immune response against these self nucleic acids that are necessary for
normal cellular function? Right Ans - The TLRs that recognize ssRNA and
dsDNA are sequestered in endosomes.
How can the antiviral state be propagated in the absence of immune cells?
Right Ans - Type I IFNs are produced by infected epithelial cells; this induces
anti-viral biochemical changes in the same cell and adjacent cells.
A child presents with recurrent bacterial infections. Of the genetic defects
described below, what is the most likely cause of her disease? Right Ans - A
mutation in the C3 gene that renders the C3 protein nonfunctional.
____________ is the process by which something that is not otherwise recognized
as a pathogen is coated with proteins that make it more recognizable to the
immune system. Right Ans - Opsonization
, The majority of the symptoms of tetanus infection are caused by the tetanus
toxins, chiefly tetanospasmin. Tetanospasmin is one of the deadliest toxins
known; even very small doses (nanograms) can be lethal. It targets the nerves,
causing severe muscle spasms. The tetanus vaccine consists of inactivated
tetanus toxin; the vaccine is highly effective for preventing tetanus.
Inoculation with the tetanus vaccine leads to the production of protective
antibodies. How do these antibodies prevent tetanus? Right Ans -
Neutralization
Streptococcus pneumoniae is an extracellular bacterium that is a leading
cause of bacterial pneumonia and meningitis, particularly in children and the
elderly. Fortunately, most cases of S. pneumoniae can be prevented with a
vaccine that contains components of the bacterial capsule. The vaccine is
known to lead to the production of antibodies that recognize intact bacteria.
What are the most likely mechanisms activated by these antibodies that result
in protection against S. pneumoniaeinfection? (select two answers) Right
Ans - The key is that S. pneumoniae is an extracellular bacterium. The vaccine
elicits a humoral immune response, which generates antibodies that bind to
the surface of the bacterium. The antibodies bound to bacteria can activate
complement (direct killing of the bacteria) and opsonization followed by
phagocytosis. ADCC is usually directed against viral proteins displayed on the
surface of cells. It is conceivable that antibodies could neutralize the function
of bacterial components, but direct killing by complement and phagocytosis
are the best-characterized mechanisms for eliminating extracellular bacteria.
There is strong interest in developing a vaccine that would prevent human
immunodeficiency virus (HIV) infection or substantially reduce viral loads in a
person with HIV. HIV infects immune cells by binding to a receptor called CD4
on the surface of those cells. Laboratory studies have identified rare
antibodies that bind to intact HIV viral particles and effectively control the
virus in certain individuals. Structural studies revealed that some of these
antibodies bind to a protein on the surface of HIV at the same location where
this protein binds to CD4.
What is the most likely mechanism of action of these antibodies? Right Ans
- Neutralization
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