1. Two of the main, early theories proposed to explain how antigen-specific antibodies develop were the instructional theory and the selective theory. How did the two differ? Which was ultimately shown to be CORRECT?
ANSWER:
The selective theory says that, when an antigen receptor binds with an antigen, the cell becomes activated (or the cell is selected to proliferate and secrete more copies of the receptor). The instructional theory says that the antigen receptor molds itself to the antigen. The selective theory was shown to be correct.
2. Often, serendipity plays a role in significant scientific discoveries. In your own words, explain how serendipity led Pasteur to discover a cholera vaccine.
Pasteur developed the vaccine in chickens, which were in short supply. He challenged groups of chickens with cholera bacteria - some of which were previously exposed to an attenuated version of cholera bacteria. Only the previously exposed animals were protected from a new challenge, which led to the use of weakened pathogens as vaccines.
3. Despite its having been eradicated on a global scale, smallpox is presently considered a potential bioterrorism threat. Why? Use evidence to support your answer.
After eradication was achieved, smallpox vaccination programs largely ended. As populations continued to grow over time, an ever-increasing percentage of the human population remains unvaccinated and thus, is still susceptible to the disease.
4. Prior to 1999, it was claimed that a thimerosal additive in vaccines was contributing to the rising incidence of autism. If the claims were true, what resultant trend might you expect to observe in the rate of autism once thimerosal was removed from vaccines?
One would reasonably expect a decrease in the rate of autism. However, cases of autism continued to rise after thimerosal was removed from vaccines in 2001.
5. Given the discovery and development of effective antibiotics, make an argument for the continued use of vaccines against bacterial pathogens. Use evidence to support your answer.
Antibiotics are used for treatment of disease, not typically for prevention. Antibiotic treatment is not foolproof (considering the rising incidence of antibiotic resistance). Vaccines are a preventative measure, and prevention is the gold standard for infectious disease control measures.
6. You have a friend unfamiliar with immunology, and he asks you the following question: "Why do I need the flu shot every year, but don't need an annual chickenpox vaccine?" As a student of immunology, how would you explain this discrepancy to your friend? Use evidence to support your answer.
The virus that causes the flu changes every year - as a result, a new flu vaccine must be prepared each year based on a predication of the most common forms of the virus likely to be encountered. Vaccines are specific in the type of pathogen against which they protect, and protection against one type does not guarantee protection against pathogens that are closely-related.
7. Provide one benefit and one drawback of generating random recognition receptors during the development of B cells.
A benefit is having the capacity to recognize and respond to diverse pathogens as they evolve. A drawback is that some recognition receptors could potentially recognize and target host antigens.
8. A portion of our immune systems' white blood cells is constantly circulating throughout the body via circulation and lymphatics. What is the benefit of such circulation?
The circulation of the white blood cells allows for a more comprehensive surveillance of the body for the presence of potential pathogens. A significant portion of the human body is constantly exposed to potential microbial pathogens.
9. Complete the following table by comparing and contrasting innate and adaptive immune responses.
Innate Immunity
Adaptive Immunity
Is mediated by what cells?
What do they recognize?
How are the receptors encoded?
Why can't they control all infections alone?
What do they do in response to antigen?
Macrophages, NK cells, neutrophils, mast cells eosinophils
T cells and B cells
Pathogen patterns
Specific epitopes
Germ line
Rearranged gene segments
Pathogens evolve escape mechanisms
Takes too long to develop
Engulf and destroy, induce inflammation
Produce antibodies, kill infected cells
10. What are the hallmarks of inflammation? Describe the physical characteristics of someone experiencing an inflammatory response.
Redness, swelling, heat, pain. Someone experiencing inflammation might have localized swelling and redness or itching or may be experiencing faintness due to a lowering of blood pressure if more severe.
11. Upon receiving immune serum as a treatment for a venomous snake bite, would the recipient be immune from future bites of the same species?
In the short-term, probably, as the serum contains protective antibodies against the venom. In the long-term, no, as serum treatment is a form of passive immunity. Passive immunity does not generate long-lived memory cells.
12. Provide one common feature of and two differences between B-cell receptors and PRRs.
A common feature is that they both are used to recognize foreign antigens. A B-cell receptor is more selective than a PRR. The DNA that encodes for a PRR in an individual is inherited. The DNA that encodes for a mature B-cell receptor from an individual is not passed on to offspring.
13. Given that an important function of the immune system is to both recognize and dispose of cancerous cells, postulate why tumors can be established in a human host.
There are two primary reasons. First, cancerous cells are self-originating, thus self-tolerance mechanisms can inhibit the development of an effective immune response. Second, as is common with some pathogens, genetic variability within a population of cancer cells gives them an advantage in terms of evading the immune response.
14. The hygiene hypothesis posits that there is a connection between environmental conditions and certain inappropriate immune responses. If you were a supporter of the hygiene hypothesis, what recommendations would you make to keep people healthier?
Expose children to more common antigens found in dirt and in the outdoors. Reduce use of antimicrobials.
15. Which is the BEST definition of "immunity"?
a.
The state of having been exposed to a pathogen repeatedly
b.
The state of being resistant to reinfection with a pathogen
c.
When an individual has never been exposed to a pathogen
d.
When the immune system is activated
e.
When physical barriers are not enough to prevent infection
b
16. What happens to a pathogen as it becomes attenuated?
It becomes more dangerous to the host.
It gets smaller.
It has weakened virulence.
It becomes older.
All of the answers are correct.
c
17. Which of the following advances can be credited to progress made in our understanding of immunology?
Smallpox eradication
Treatment of asthma
Ability to transplant human organs
Cancer treatment
e
18. Which of the following is the BEST example of herd immunity?
A child infected with measles travels from Germany to the United States. Several babies contract the disease, but the outbreak is largely contained due to vaccinations.
Certain populations of cattle are less susceptible to infection with encephalitis because of their genetic makeup.
Once a certain threshold of individuals has been infected with a novel human pathogen, it is unlikely that any more will be.
Geese and chickens are infected with different strains of influenza because they express different receptors on their cell surface.
When infection spreads through a population, certain individuals generate stronger immune responses than others.
a
19. Which of the following diseases does NOT currently have an effective vaccine?
Chicken pox
Polio
HIV
Smallpox
Diptheria
20. Examine Figure 1-8. Which cells are MOST likely responsible for the intense response to Antigen A following a second exposure?
B cells
T cells
Memory T cells
Memory B cells
Both memory T cells and memory B cells are responsible.
21. Effectors of the humoral immune system are known as
antibodies.
immunoglobulin.
complement.
B cells.
22. Which of the following cell types are lymphocytes?
Macrophages
Mast cells
Neutrophils
Erythrocytes
23. Which of the following is TRUE about antigens?
They are always derived from pathogens.
They are always proteins.
They are recognized by T cells or B cells.
They must be microbial in origin.
They usually cause cellular damage.
24. Which of the following is a fungal pathogen?
Vibrio cholera
Leishmania major
Poliovirus
Candida albicans
Bordetella pertussis
d
25. True or False? Overall, the human immune system views microbes as pathogens.
True
False
26. Which of the following factors has been shown as potentially impacting immune homeostasis in favor of inflammation?
Diet
Stress
Microbiome composition
None of the answers are correct.
27. Many of the ideas raised by Ehrlich's conception of selective theory were true. Which of the following ideas (if any) were later shown to be FALSE?
Interaction between a cell-bound receptor and pathogen could induce the cell to proliferate.
The specificity of receptors was determined in the host prior to exposure to a foreign antigen.
The antigen selected the appropriate receptor in a specific manner.
The binding of a receptor to an infectious agent was like the fit between a lock and a key.
All the ideas listed were shown to be true.
28. Which of the following cell types is MOST commonly associated with recognizing antigens found inside of cells?
TH cells
CTLs
Antibodies
29. Which of the following classes of cell surface receptors are directly encoded in the germ line?
TCR
BCR
PRR
30. What is the central mechanism for establishing self-tolerance?
Self-reactive T cells and B cells are killed during development.
Individuals that have immune systems that respond to self-antigens do not survive to reproduce.
Immune cells that react to self-antigens are turned off when they recognize self-tissues.
Certain immune suppressive cytokines are maintained in tissues to dampen auto reactive immune responses.
Peripheral tissues have mechanisms to kill T or B cells that respond to them.
31. Which of the following BEST describes chemokines?
Membrane receptors that detect the presence of soluble messengers in the environment
Soluble proteins that recruit specific cells to an area
Chemical messengers that induce cell differentiation
Transcription factors that induce the expression of genes involved in cell adhesion
Adhesion molecules that bind to the inside of blood vessels
32. Which of the following statements BEST differentiates innate and adaptive immune responses?
Innate responses are stronger during the primary and less important during the secondary response, whereas adaptive responses are less robust during primary responses and stronger during secondary responses.
Innate responses are weaker during the primary and more robust during the secondary response, whereas adaptive responses are stronger during the primary and weaker during secondary responses.
Innate responses are slower and weaker than adaptive responses.
Adaptive responses are slower and weaker than innate responses.
Adaptive responses are required for effective immune responses, whereas innate responses are not required.
33. True or False? The innate and adaptive immune responses work largely independently of one another.
34. How do memory cells develop?
Upon reinfection, memory centers in the brain send signals to the bone marrow to induce T-cell and B-cell differentiation.
T cells and B cells from the primary response persist and become reactivated.
Innate cells are trained to activate new T cells and B cells more quickly with secondary infection.
T cells and B cells from the primary infection slowly mutate their receptors over time, priming themselves for the secondary response.
Innate cells modify their cell surface receptors to prepare for reinfection.
35. Which of the following is the BEST example of a hypersensitivity reaction?
T cells responding vigorously to the flu virus
B cells failing to respond to HIV, allowing it to replicate out of control
Inflammation of the airways in response to pollen
Anemia as a result of iron deficiency
T cells attacking the myelin sheath of nerves resulting in paralysis
36. HIV disease is a(an)
autoimmune disease.
hypersensitivity disease.
immunodeficiency.
genetic disorder.
allergic reaction.
37. Predict the outcome of being immunosuppressed as it relates to the development of cancer.
Immunosuppressed individuals are at lower risk of cancer because cytokines produced by the immune system induce cancer.
Immunosuppressed individuals are at lower risk of cancer because they are more likely to contract infectious diseases.
Immunosuppressed individuals are at higher risk of cancer because the immune system recognizes and destroys cancerous cells.
Immunosuppressed individuals are at higher risk of cancer because they bear a higher load of microbes that damage host tissues.
38. What occurs when someone receives a tissue transplant from an unrelated individual?
The host's lymphocytes enter the tissues and become suppressed.
The host's lymphocytes enter the tissues and become activated.
The host's lymphocytes that react to the tissue graft are deleted in the thymus.
The donor's lymphocytes suppress the host's lymphocytes, allowing for graft survival.
The donor's lymphocytes destroy the host's immune system.
39. Which of the following is TRUE?
Vaccines cause autism.
Vaccines cause obesity.
Vaccines cause cancer.
Vaccines cause diabetes.
40. Conditions in which the immune system attacks self-antigens are known as
autoimmunity.
immune deficiency.
hypersensitivities.
neuroplasias.
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