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IMY521S - IMMUNOLOGY - 1ST OPP - NOVEMBER 2023 |
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n Am I B I A u n IVE Rs I TY
OF SCIEnCE AnDTECHnOLOGY
Facultyof Health, Natural
Resourcesand Applied
Sciences
School of Health Sciences
Department of Clinical
Health Sciences
13Jackson Kaujeua Street
Private Bag 13388
Windhoek
NAMIBIA
T: +254 51 207 2970
F: +254 51 207 9970
E: dchs@nust.na
W: www.nust.na
QUALIFICATION : BACHELOR of MEDICAL LABORATORY SCIENCES
QUALIFICATION CODE: 08BMLS
LEVEL:5
COURSE:IMMUNOLOGY
COURSECODE: IMY521S
DATE: NOVEMBER 2023
SESSION: 1
DURATION: 3 HOURS
MARKS: 100
FIRST OPPORTUNITY: EXAMINATION QUESTION PAPER
EXAMINER:
MODERATOR:
MRS. CARAMIA DUNAISKI
MRS. FREDRIKAENGELBRECHT
INSTRUCTIONS:
1. Answer all questions on the separate answer sheet.
2. Please write neatly and legibly.
3. Do not use the left side margin of the exam paper. This must be allowed for the
examiner.
4. No books, notes and other additional aids are allowed.
5. Mark all answers clearly with their respective question numbers.
PERMISSIBLE MATERIALS:
1. Non-Programmable Calculator
ATTACHMENTS: None
This paper consists of 7 pages including this front page
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SECTION A: MULTIPLE CHOICE
[20 MARKS]
QUESTION 1:
[20 MARKS]
Evaluate the statements in each numbered section and select the most appropriate answer or
phrase from the given possibilities. Fill in the appropriate letter next to the number of the correct
statement/phrase on your ANSWERSHEET.
1.1 In the immune response to a hapten-protein conjugate, in order to get anti-hapten (1)
antibodies, it is essential that;
a) Hapten be recognized by helper T-cells.
b) The hapten be recognized by natural killer-cells.
c) The hapten be recognized by suppressor T-cells.
d) The protein be recognized by 8-cells.
e) The protein be recognized by helper T-cells.
1.2 Antigen-presenting cells that activate helper T-cells must express which one of the (1)
following on their surface?
a) CD4
b) ClassI MHC
c) ClassII MHC
d) lgM
e) Thy-1
1.3 One principal function of complement is to:
(1)
a) Bind antibodies attached to cell surfaces and to lyse these cells.
b) Cross-link allergens.
c) Inactivate perforin.
d) Mediate the release of histamine.
e) Phagocytose antigens.
1.4 Cytokines always act:
(1)
a) Antagonistically with other cytokines.
b) From a long range.
c) By binding to specific receptors.
d) In an autocrine manner.
e) Synergistically with other cytokines.
1.5 Which of the following cytokines is characteristically produced by Th2 lymphocytes (1)
which provide help for antibody production?
a) GM-CSF
b) IL-1
c) IL-4
d) IFN-y
e) TNF-a
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1.6 High-affinity B cell clones are usually generated by:
(1)
a) Class switching.
b) Expression of high affinity precursors in the naive B cell population.
c) Positive selection.
d) Negative selection.
e) Somatic hypermutation.
1.7 Prior to class-switching, B cells express:
(1)
a) lgA
b) lgA and lgG
c) lgD
d) lgD and lgM
e) No surface antibody
1.8 Which of the following is a primary lymphoid organ?
(1)
a) Lymph nodes
b) Peyer's Patches
c) Spleen
d) Thymus
e) Tonsil
1.9 When antigen reaches the lymph node:
(1)
a) There is an increase in the number of cells leaving the lymph node.
b) There is a decrease in the number of cells leaving the lymph node.
c) There is an immediate increase in the number of activated B cells.
d) It is transported to the spleen.
e) It is immediately destroyed by the macrophages.
1.10 The specialised cell type involved in the entry of lymphocytes into a lymph node is (1)
called:
a) HEV endothelial cells.
b) M cells.
c) PALScells.
d) Selectins.
e) Synovial cells.
1.11 The following is characteristic of B cells but not T cells:
(1)
a) CD3
b) CD40 ligand
c) MHC class I
d) Polyclonal activation by concanavalin A
e) Surface immunoglobulin
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1.12 A Fab fragment:
(1)
a) Is produced by pepsin treatment.
b) Is produced by the separation of heavy and light chains.
c) Binds antigens.
d) Lacks light chains.
e) Has no interchain disulphide bonds.
1.13 Pattern recognition receptors include:
(1)
a) PAMPs.
b) LPS.
c) Lipotechoic acid.
d) Lectin-like molecules.
e) Bacterial peptidoglycan.
1.14 The complement component C3 is cleaved by:
(1)
a) Factor D.
b) C4b2a3b.
c) C3bBb.
d) C3b.
e) Cls.
(1)
1.15 C3b:
a) Opsonises bacteria.
b) Is an anaphylatoxin.
c) Is chemotactic.
d) Is the inactive form of C3.
e) Directly injures bacteria.
1.16 Positive selection in the thymus is mediated by:
(1)
a) B cells.
b) Cortical epithelial cells.
c) Follicular dendritic cells.
d) lnterdigitating medullary cells.
e) Macrophages.
1.17 Specific antibodies are readily detectable in serum following primary contact with (1)
antigen after:
a) 10 minutes.
b) 1 hour.
c) 5-7 days.
d) 3-5 weeks.
e) Only following a second encounter with the antigen.
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1.18 The antigen portion on an antigen -presenting cell that is recognised by the al3-TCRis: (1)
a) The native protein antigen together with the Major Histocompatibility Complex
molecule.
b) Processed peptide antigen together with the Major Histocompatibility Complex
molecule.
c) Processed peptide antigen.
d) Native antigen.
e) The Major Histocompatibility Complex molecule alone.
1.19 Antigen processing for presentation by an MHC class II molecule involves:
(1)
a) Calnexin.
b} HLA-DM.
c) LMP2.
d) Proteasome.
e) TAP 1 and TAP 2.
1.20 Suppression ofTh2 lymphocytes by Thl lymphocytes may be mediated by:
(1)
a) IL-4.
b) GM-CSF.
c) IL-1.
d) TNF-!3.
e) INF-y.
SECTION B: SHORT AND LONG QUESTIONS
[80 MARKS]
QUESTION 2:
[10 MARKS]
A 54-year-old female presented at her GP with a history of stiffness in her joints in the mornings
which normally lasted more than an hour and arthritis which was becoming progressively worse.
Rheumatoid nodules were visible particularly in her hands. Analysis of her blood revealed elevated
levels of rheumatoid factors. The doctor placed her on a regimen of medication to control the
disease. This included monoclonal antibodies against tumour necrosis factor-alpha (TNF-a) which
is implicated in rheumatoid arthritis. Rheumatoid arthritis is more frequently observed in patients
with HLA-DR4allele. Answer the following questions.
2.1 Define Cytokines and list three (3) major functions.
(4)
2.2 Sketch and label the MHC class II molecule that is associated with rheumatoid
(6)
arthritis.
QUESTION 3:
[10 MARKS)
Vaccines have changed the face of medical science. Through successful vaccination strategies, the
burden of infectious disease has decreased around the world.
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3.1 Define the term "Vaccination".
(2)
3.2 Name the first disease that was successfully eradicated from the world by means of a (1)
vaccination campaign.
3.3 Louis Pasteur's work with chicken cholera contributed to our understanding of why (7)
vaccination is possible. Describe the "accidental" experiment that he conducted. In
your answer, include an explanation of his findings.
QUESTION 4:
(30 MARKS]
A 38-year old woman with severe pre-eclampsia gave birth to a healthy baby girl (Monica) via C-
section in her 30th week of pregnancy. The new born weighed 1.3 kg and had no obvious congenital
abnormalities. As a result of her premature birth, the cord blood was sent to the laboratory to
establish the immunoglobulin concentration. Her serum lgG was 0.lg/litre. The normal range for
lgG in a neonate is normally the same as that of the mother i.e. 7.2-19 g/liter. A diagnosis of
hypogammaglobulinaemia of prematurity was made. Answer the following questions.
4.1 Why does a neonate normally have the same concentration of lgG as the mother's at (2)
birth?
4.2 If Monica were to develop an infection within her first week of life, passive immunity
could be achieved.
4.2.1 What would passive immunity entail?
(1)
4.2.2 Why would passive immunity be administered?
(3)
4.2.3 Would the passive immunity give her life-long protection? Motivate your
(2)
answer.
4.3 On day 10, the infant was diagnosed with a bacterial infection. Staphylococcus aureus
is a bacterial species that causes extracellular infections.
4.3.1 Describe how the bacteria would be processed into peptides which are then (10)
presented to T lymphocytes.
4.3.2 Name the type of immune response that would predominate. Motivate your (2)
answer.
4.3.3 Name the class of antibody that would be initially produced after a (2)
lymphocyte's first encounter with Staphylococcus aureus.
4.3.4 Sketch and label lgG antibody.
(8)
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QUESTION 5:
[30 MARKS]
A 15 year old male developed pneumonia and was placed on Penicillin. He developed puffy eyes,
urticaria, a swollen face and wheezing. This was not the first time he had been placed on penicillin
for the treatment of bacterial infections. Tests to determine the presence of complement proteins
revealed that the level of complement was below the normal levels. He was diagnosed with drug-
induced serum sickness. Serum sickness results from the formation of small immune complexes in
the presence of excess antigen. These small immune complexes are not removed from the
circulation and instead are deposited in the tissue. The immune system tries to rid the body of
these deposited immune complexes by activating complement proteins. Anaphylatoxins which are
released during the activation of complement contribute to the inflammatory responses which
manifested in the symptoms he exhibited. Answer the following questions.
5.1 Normally complement-opsonized immune complexes can be removed from (4)
circulation with the aid of phagocytes. Explain how the phagocytes carry out this
function.
5.2 Name the complement pathway that is activated in this scenario where immune (2)
complexes are deposited in tissues.
5.3 Describe the formation of membrane attach complex (MAC) in the pathway you (15)
named in 5.2.
5.4 In the scenario above anaphylatoxins are produced and cause an inflammatory (4)
response. What are these anaphylatoxins and describe their role in inflammation?
5.5 Define hypersensitivity and briefly explain how the four types are differentiated from (5)
each other.
END OF QUESTION PAPER
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