HMX Immunology Final Exam
One 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 infec...
HMX Immunology Final Exam
One 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 - Answer- Epithelial barriers
Which of the cells below are tissue resident sentinel cells - Answer- 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) - Answer- Neutrophils
Monoctyes
Mast cell - Answer- Cells that release chemicals (such as histamine) that promote
inflammation.
Neutrophil - Answer- Most abundant leukocyte
Phagocyte that rapidly dies after ingesting microbe
macrophage - Answer- Phagocyte that cleans up apoptotic cells
When a monocyte moves into the tissues, it changes rapidly and becomes a
____________ . - Answer- 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? - Answer- 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 - Answer- 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? - Answer-
Immunodeficiency with a susceptibility to bacterial infections.
The complement pathway initiated by host proteins that bind to microbial sugars is
called the ____________ pathway. - Answer- 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? - Answer- The TLRs that recognize ssRNA and dsDNA are
sequestered in endosomes.
How can the antiviral state be propagated in the absence of immune cells? - Answer-
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? - Answer- 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. - Answer- 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? - Answer- 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) - Answer- 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? - Answer-
Neutralization
How many distinct peptide chains are found in a single molecule of IgG? - Answer-
Each IgG antibody is comprised of two heavy chain and two light chain peptide
chains joined by disulfide bridges.
How many distinct binding sites are found in a single molecule of IgG? - Answer-
Two
Which of the following antibodies is protected from proteases that are commonly
found in the gut? - Answer- IgA
Neutrophils, NK cells, and macrophages all have receptors for the
__________________ portion of the antibody, and use this to recognize antigens
that are coated with antibodies. - Answer- Fc
Antibodies can cause disease by: - Answer- a combination of complement fixation
and opsonization, leading to frustrated phagocytosis and inflammation-mediated
damage
forming complexes in the circulation that can deposit in vessel walls and potentially
trigger further immune activation
recognizing antigens that are part of our own cells, leading to opsonization and
destruction by phagocytes
recognizing antigens that are part of our own cells, leading to complement activation
Which of the following is an example of an autoimmune disease caused by
antibodies that interfere with the function of a self protein? - Answer- Antibodies bind
to receptors for a neurotransmitter, leading to paralysis.
Which of the following are components of an adaptive immune response to
pathogen? (Select two answers.) - Answer- clonal selection by specific antigen
clonal expansion
A researcher suspects that a certain leukocyte population plays a role in a particular
disease. She studies mice with a genetic defect that leads to the development of the
disease in young mice. She decides to test her hypothesis by surgically removing the
thymus from newborn mice, then observing these mice for disease progression.
What leukocyte population does she suspect contributes to the development of the
disease? - Answer- T cells
Which of the cells below are granulocytes? (Select two answers.) - Answer-
Granulocytes are a group of cells with secretory granules, they include neutrophils,
basophils and eosinophils.
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