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12. The
following properties render a substance immunogenic:
q
high molecular weight
q
chemical complexity
q
sufficient stability and persistence
after injection
q
all of the above
q
all of the above are essential but not
sufficient
13. The
graph here reported exemplifies the differences in the primary and secondary
response to an antigen, reflecting the phenomenon of immunological memory. Try
and explain why.
14. Which
of the following is expressed on the surface of mature B lymphocytes?
q
CD40
q
MHC class II molecules
q
CD32
q
IgM and IgD
15. Which
of the following statements is incorrect
q
Antibodies in a secondary immune response
generally have a higher affinity for antigen than antibodies formed in a
primary immune response
q
Somatic hypermutation of V region genes
may contribute to changes in antibody affinity observed during secondary
responses
q
Synthesis of antibody in a secondary
response occurs predominantly in the blood
q
Isotype switching occurs in the presence
of antigen
q
Predominantly IgM antibody is produced in
the primary response
16. The
germinal centers found in the cortical region of lymph nodes and the
pheripheral region of splenic periarteriolar lymphatic tissue
q
support the development of immature B and
T cells
q
function in the removal of damaged
erythrocytes from the circulation
q
act as a major source of stem cells and
thus help to maintain hematopoiesis
q
provide the infrastructure that on
antigenic stimulation contains large populations of B lymphocytes and plasma
cells
q
are the site of NK-cell differentiation
17. Both
B and T lymphocytes can exhibit immune memory
q
False
q
True
18. Western
assays used to test serum samples for the presence of antibodies to infectious
agents, such as HIV are particularly useful as diagnostic assays because
q
They are more sensitive than ELISA
q
Antibodies specific for multiple
antigenic epitopes can be detected
q
They provide quantitative data for sample
analysis
q
They allow multiple samples to be tested
simultaneously
q
They are less expensive and take less
time to perform as compared with ELISA
19. An
ELISA designed to test for the presence of serum antibody for a new strain of
pathogenic bacteria is under development. Initially, a monoclonal antibody
specific for a single epitope of the organism was used both to sensitise the wells
of the ELISA plate and as the enzyme-labeled detecting antibody in a convenient
sandwich ELISA. The ELISA failed to detect the antigen despite the use of a
wide range of antibody concentrations.
What is the most probable cause of this problem?
q
The antigen is too large
q
The antibody has a low affinity for the
antigen
q
The monoclonal antibody used to sensitise
the wells is blocking access to the epitope, thus when the same antibody is
enzyme labeled, it cannot bind to the antigen
q
The enzyme labeled antibody used should
have been a different isotype than the sensitising antibody
q
The monoclonal antibody used is probably
unstable
