Deck 11: Host Defense

Question 1

Which of the following vaccine types best mimics a genuine infection?

A) a vaccine made with an attenuated pathogen
B) a vaccine made with an inactivated pathogen
C) a subunit vaccine
D) Both "a" and "c" closely mimic a genuine infection.
E) Both "b" and "c" closely mimic a genuine infection.

Answer 1

A

Question 2

How does HIV reduce immune function?

Answer 2

HIV infects and kills helper T-cells. These cells are central to a proper adaptive immune response. Helper T cells are the component of adaptive immunity that is stimulated by antigen presenting cells during an infection. Once activated, helper T-cells can activate cytotoxic T-cells to initiate a cell mediated response and B cells to initiate a humoral response. Over time, an HIV infection can result in a greatly reduced number of helper T cells. Consequently, although healthy populations of cytotoxic T-cells and B-cells remain, without enough helper T-cells they cannot be activated properly, and both cell mediated and humoral responses decline, opening the door to the opportunistic infections that are characteristic of advanced AIDS.

Question 3

In what way can the fever response be used to illustrate the point that response to pathogens can both be protective and harmful?

Answer 3

In many infections, certain cytokines released by various cells act on a specific part of the brain to elevate body temperature. In other words, these cytokines stimulate fever. A fever can be a beneficial part of an innate immune response. At elevated body temperature, phagocytic cells are more efficient, and some pathogens are less able to reproduce. Fever, however, is uncomfortable, and is often recognized as one of the symptoms of many diseases. It fever gets too high, it can actually be dangerous or even life-threatening. Thus, while part of a protective immune response, fever, like many aspects of immunity, actually contributes to the symptoms observed during infectious disease.

Question 4

During a successful secondary immune response:

A) the inductive period will be longer than it was during a primary response.
B) greatly increased levels of IgM are produced.
C) long-lived plasma cells immediately begin secreting antibody.
D) the number of pathogens should remain below the threshold of disease.
E) there will be a stronger cell-mediated response, but a less vigorous humoral response.

Question 5

Toll-like receptors:

A) permit certain innate immune system cells to recognize certain molecules that are unique to microorganisms.
B) are found on the surface of cytotoxic T cells, and are used to recognize infected cells.
C) present foreign antigens on the surface of macrophages and dendritic cells.
D) are found on the surface of helper T cells, where they recognize antigens presented by antigen presenting cells.
E) are used by macrophages and dendritic cells to signal helper T cells that an infection is under way.

Question 6

Which of the following is true about interferon?

A) It is released by uninfected cells during a viral infection.
B) It is produced by virally infected cells during a viral infection, whereupon it inhibits further viral replication within the cells where it is made.
C) It is produced by virally infected cells to activate helper T-cells.
D) It is released by virally infected cells to induce an antiviral state in uninfected cells.
E) It is released by cells in lymph nodes to attract T cells to the lymph node.

Question 7

Which antibody type is usually produced in the greatest amount during a humoral reponse?

A) IgA
B) IgD
C) IgM
D) IgE
E) IgG

Question 8

Which of the following cell types can be considered to be part of the innate immune system?

A) red blood cells
B) neutrophils
C) helper T cells
D) cytotoxic T cells
E) B cells

Question 9

Which of the following is not a correct and necessary step in the generation of a cell-mediated response?

A) Antigen presenting cells are activated by pattern recognition.
B) Antigen presenting cells present antigen to helper T cells.
C) Antigen presenting cells activate cytotoxic T cells.
D) Helper T cells release cytokines that stimulate activate cytotoxic T cells.
E) Cytotoxic T cells recognize their specific antigen on the surface of infected cells.

Question 10

B-cells are able to recognize antigens because they have specific receptors on their surfaces that bind specific antigens. These receptors are called ________.

A) toll-like receptors
B) pattern recognition receptors
C) MHC
D) IgG
E) IgM

Question 11

Describe how cells of the innate immune system activate the adaptive immune system under certain circumstances.

Question 12

Which of the following is a good example of how innate and adaptive immunity depend on each other?

A) the release of perforin by cytotoxic T cells
B) presentation of the antigen by virally infected cells
C) phagocytosis of pathogens by neutrophils
D) the activation of humoral immunity by helper T cells
E) the ability of antibodies to function as opsonins

Question 13

Which of the following immune system structures and their associated function is not correct?

A) thymus: maturation of T-cells
B) lymph node: generation of adaptive immune responses in tissues
C) spleen: generation of adaptive immune responses in the blood
D) liver: maturation of B-cells
E) skin: a barrier to entry