2016 immuno 5-6 practice final answers

8/18/2019 2016 Immuno 5-6 Practice Final Answers

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The upcoming exam is based on Dr. Lopez’s virology lectures and lecture 5 and lecture 6 of thepreceding immunology. There will be 17 immunology questions on exam 4 and I am providingyou with 20 practice questions. Your goal should be to understand, and if necessary research,why you are checking off an answer as correct and why the other answers offered are not. Toencourage you to go through this process first, I will release the answers to the practice

questions tonight at 9 PM.

Regarding the question, “Do I need to know x-y-z for the exam?” my answer will be YES – asyou already know. Also, learning means trying to gain understanding first on your own. Didyou look through the lecture slides and your notes? Thereafter, please discuss with your studygroup. If you still don’t understand, find the PowerPoint slide from the lecture slides thatcomes the closest to your question. Type your concise question into the annotation panel ofthis PowerPoint slide. The deadline for the submission of questions is Wednesday at 6 PM(Email subject line: MIC 301/303/320 exam question slide; Email address:[email protected]). Please follow these instructions so that I can combine all questionsand answers into a single PowerPoint for all students.

As before, some of the formats of the practice questions are different from the format of theexam question that only ask you to identify the one best answer among four options. Pleasealso note that the lecture material comprises more testable material than the questions below.Finally, note that I hold a copyright on my questions. Therefore, you are agreeing not todistribute, publish, copy, broadcast, rewrite or redistribute in part or whole any of thequestions with individuals other than those enrolled in the 2016 MIC301/303/320 class. Thankyou for your attention to all of the above matters and productive studying!

1. Regarding MHC molecules, all of the statements below are correct, EXCEPT THREE:

a.

They are encoded by polymorphic genes. b. Their identities are determined by the parental alleles of a person.c. They are encoded by two major classes of genes in humans.

d. Each of the two classes of genes consists of subfamilies with many individualmembers.

e. Expressed class I genes are different in each cell of our body.f. With the exception of identical twins, the MIC301/303/320 students are likely to

express different combinations of their HLA gene loci.g. MHC loci are randomly rearranged during the development of antigen presenting

cells to accommodate diverse pathogens.h. They are only expressed by antigen-presenting cells.

i.

The biological design and function of MHC molecules accommodates peptidesfrom an “unlimited” number of pathogens.

2. Autoreactive T-cells are constantly produced in the thymus, including, for example, CD8T-cells that can recognize insulin-producing cells in the pancreas. Nevertheless, most of

us do not suffer from type I diabetes, a condition in which such T-cells can attack anddestroy cells producing insulin. What are the three main reasons that most of us do not

develop type I diabetes?

• Deletion of self-reactive T-cells during their development (negative selection)


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• Negative control of self-reactive T-cells by regulatory T-cells

• Need for "danger" signals to activate costimulatory molecules on DC to initiate animmune response. Cells other than professional antigen presenting cells cannot

express costimulatory molecules and thus will anergize T-cells rather thanactivate T-cells.

3. Immunologically, the most important reason for the expression of HLA class I molecules

by all nucleated cells in our body is that __________.a. they are required for the generation of antibodies

b. they enable the immune system to “see” “hidden” intracellular pathogens from the“outside” of cells

c. they enable T-cells to recognize cells presenting extracellular antigensd. they are needed to perform the matching of organ transplants

e. they cause protection of our cells by type I IFN production

4.

The immunological purpose of active vaccinations is to __________.

a. generate antigen-specific memory cells resulting in long or even life-longimmunity

b. use the cheapest means of immunological protectionc. avoid the use adjuvants

d. provide immediate protection of immune-compromised individualse. render haptens immunogenic

5. Describe the order of events that protect our body from succumbing to viral infections.

Differentiate two groups for the events, one for the innate immune response and the other

for the adaptive immune response.• Innate: Infected cells themselves produce type I IFNs (alpha and beta) which

promote antiviral activity for themselves and their uninfected neighbors. Type IIFN also strongly upregulates killing by NK cells. NK cells will kill virally

infected cells after detecting that they are “sick”. This is not antigen-specific!They also produce IFN gamma to turn on macrophages to remove the dying

corpses. IFNa alpha strongly activates dendritic cells (DC) that are the “bridge”to the adaptive immune system). DC will take up remnants of the dead cells

(including their viral proteins) and process these antigens and deliver them to thedraining lymph node.

• Adaptive: Antigen-specific naïve CD8 T-cells will be activated by dendritic cells

and this process will be facilitated by the activation of CD4 T-helper cells andtheir secretion of cytokine onto the CD8 T-cells. These cells begin to replicate,

acquire cytotoxic activity, will exit the lymph node and reach the infected tissuevia the lymphatics followed by their circulation into the blood from where they

reach the infected tissue and kill the virally infected cells.


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6. MHC class II molecules __________.a. interact with CD8 molecules

b. accommodate only one unique peptide in their peptide binding groovec. are the receptor for the human immunodeficiency virus

d. can interact with superantigens

e.

–– or more concisely –– their absence, activates NK cellsf. are two-times larger than MHC class I molecules.

7. CD4+ T-cells ________ (two answers are correct).

a. produce antibodies. b. develop in the bone marrow.

c. express MHC class I molecules, just like any other nucleated cell.d. recognize peptides presented in the context of MHC class I.

e. recognize peptides presented in the context of MHC class II

8.

Antigen recognition by T-cells (but not B-cells) involves all EXCEPT __________.

a. one or more peptides derived from the antigen b. the MHC of the individual

c. the blood group of the individuald. the function of the proteasome for antigen recognition by CD8 T-cells

e. the function of the endosome/lysosome for antigen recognition by CD4 T-cells

9. NK cells _________ (two answers are correct).

a. are activated by dendritic cells in the draining lymphnode b. kill through production of superoxide radicals

c.

become strongly inhibited in killing target cells as the targets express more MHCclass I molecules

d. kill virally infected cells or tumor cells upon recognizing a little bit of viral protein or oncogene in the context of MHC class I

e. use pore formation as a conduit for the delivery of apoptosis activating molecules

10. Important principals of passive vaccination include that _________.

a. it can be most readily used to support a humeral defense b. it can be highly effective in the prevention of infectious disease as well as its

treatmentc.

it is effective immediately

d. All answers are correct.11. Which pair associates a disease with its appropriate treatment?

a. allergy / hyperimmunoglobulin injections b. autoimmunity / anti-CTLA-4 treatment

c. autoimmunity / active vaccination with the autoantigend. allergy / pharmacological blockade of histamine actions


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12. Which statement regarding tumor and tumor therapies is FALSE?a. Emerging tumors can be controlled by NK cells.

b. Large and quickly growing tumors often have evaded the immune system.

c.

The CTLA-4 antibody used in melanoma therapyactivates

regulatory T-cells.d. Not infrequently, a tumor response to anti-CTLA-4 treatment is accompanied byinitiation of an autoimmune disease.

e. Unlike previous chemotherapy treatments, anti-CTLA-4 treatment, or the use ofsimilar so-called checkpoint inhibitors, has increased the 5-year survival of

patients with certain previously uncurable metastatic cancers.

13. Which of the following cells or molecules relate THE LEAST to the defense of large

extracellular parasites?a. B-cells

b.

Mast cellsc.

CD8 T-cells

d. Eosinophilse. Basophils

14. Which of the following statements about CD8 T-cells is FALSE?a. Naïve CD8 T-cells cannot kill.

b. CD8 T-cells are activated by antigens in solution (“floating” antigens).c. An activated CD8 T-cell can kill several infected cells, one by one, as long as

they are infected by the same intracellular pathogen.d. Cytotoxic T-cell responses usually require activation of antigen-presenting

dendritic cells and activation of CD4 T-cells.e. After their activation, cytotoxic T-cells use similar means to kill their target cells

as NK cells (perforin + granzymes).

15. Exposure and infections with certain pathogens appear to prevent a certain type of

immune disease. What are the pathogen and the disease and how are they linked insimplistic terms?

• Pathogen: Large extracellular parasites

• Disease: Allergies

•

Explanation: Antibodies of the IgE isotype are used by mast cells, eosinophils and basophils as surrogate receptors to direct their activity and release of toxic

materials onto parasites recognized. The parasite is recognized by the antigen binding site of the antibody while the mast cells, eosinophils and basophils bind

IgE due to its unique Fc portion.If IgE responses are not used against pathogens the immune system will “invent”

a reason to exercise this armory by reacting against harmless substances. Thisconcept is also reflected in the hygiene hypothesis.


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16. Upon infection of an epithelial cell of your bronchus with a newly evolved flu strain, _______________ .

a. viral proteins will be immediately recognized by effector cells that express on

their surface CD4 b. neighboring cells will quickly become more resistant to viral infection even if thisis your first infection with this viral strain

c. neighboring cells will quickly become more resistant to viral infection only if youhave been infected once before with the same virus

d. usually NK cells fail to kill virally infected cellse. histamine release by mastcells is triggered

17. Your friend has been stung by a bee for the third time in a month and complains aboutdifficulty breathing and a sudden onset of dizziness. Why is this a serious event that

should remind you of your MIC301/303/320 class?• The history (bee sting) and the symptoms (difficulty breathing and dizziness) are

classic for the beginning of an anaphylactic shock.

•

Rather than only activating the release of histamine by mast cells in the vicinity ofthe bee sting, some of the venom (the usual allergen of bees) got into the blood

and circulation where it now systemically activates mast cells throughout the body.

• The systemic release of histamine causes bronchospasm (difficulty breathing) andthe opening of capillaries throughout the body (reduced blood pressure andultimately shock).

18. Explain why superantigens a) activate CD4 T-cells and b) why this activation is notantigen-specific.

• They bind to CD4 and MHC class II molecules on professional antigen presentingcells.

• Unlike antigen peptides they do not bind to a groove in the MHC class IImolecule but instead to a side portion that is well conserved throughout all MHC

class II genes. This mimics a triggering of a signal activating the CD4 T-cells.

19. Explain why a single MHC molecule can present a large number of different peptides

from different antigens.• The rules for a peptide to fit into the groove of an MHC molecule are determined

by the length of the groove. Millions of peptides with identical length (but with

different composition of their amino acids) are produced during antigen processing.

• The number of peptides that can be accommodated is slightly reduced, however, by the need for two (or three) specific amino acid in two (or three) positions of a peptide. These amino acids anchor the peptide within the groove of MHC


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molecules and, hence, they are referred to as the anchor residues. Each MHCmolecule has its own specific anchor residues.

20. Allergy and autoimmunity __________.

a.

are interchangeably used to describe one identical type of immune response b. involve the production of antibodies belonging to the IgE isotypec. are caused by cytotoxic T-cells

d. are curable by the injection of CTLA-4 antibodiese. are treated by bone marrow transplantation

f. are caused by harmless innocuous foreign substances in the case of allergies, and by self antigens in the case of autoimmunity

2016 immuno 5-6 practice final answers

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