Download Document

Biol 430
Question Bank
TCRs and T-cells
1. Summarize the main characteristics of the different types of TH cells
Effector
Main Target Cells
Functions
TH1
TH2
TFH
TH17
Treg
2. Identify the components of the TCR-complex labeled as A- E in
this diagram and briefly identify the function of each in the T-cell
activation process.
3. What are the characteristics of a T-cell precursor that will allow it to proceed from a:
A. DN state to a DP state:
B. DP state to a SP state:
How is the fate of SP cell determined as TH or Tc?
Biol 430
Question Bank
TCRs and T-cells
Page 1
4. DCs are required for the activation of naïve TH and Tc cells; and TH cells activate (license) DCs.
A. What stimuli are provided from the TH cell to the DC cell as it becomes licensed?
B. What stimuli are provided from the DC cell to the TH cell as it becomes activated?
C. Although they do not interact directly, TH cell activation is necessary for Tc cell activation.
What is uncertain presently about the process of Tc cell activation?
D. Why do you think such a complex set of interactions is necessary for Tc cell activation?
5. Match these CTL effector mechanism terms with their best definition:
Component
Function
____ caspase
A. pore-forming protein
____ granzyme
B. specialized for destruction of viruses
____ perforin
C. component of cytokine apoptosis pathway
____ Fas
D. apoptosis-linked membrane receptor
____ TNF
E. apoptosis-triggering protease released from CTL
F. apoptosis-linked protease cascade in target cell
6. Different types of T-cells are activated under different condition. Based on the information give
below, identify the type(s) of T-cell that could be activated from the following choices:
CTL, naïve TH-cell, naïve Tc-cell, memory T-cell, effector TH1, effector TH2,
A.
Activator:
Normal DC
B.
Licensed DC
C.
Macrophage
D.
B-cell
E.
Infected cell
Biol 430
Possible T-cell type(s)
Question Bank
TCRs and T-cells
Page 2
7. You have a CTL clone from an H-2k mouse that has a T-cell receptor specific for the male specific
H-Y antigen. You use the α and β TCR genes for this H-2k-restricted TCR to prepare transgenic mice
with either a H-2k or H-2d haplotype. The transgenic mice produce H-Y specific T-cells without any
further gene rearrangements.
A. Would anti-H-Y CTL cells from a H-2k male mice be able to recognize H-Y peptides presented
on MHC-I from a syngeneic H-2k mouse? … What about on MHC-I from an H-2d mouse?
Explain.
B. Will the H-Y antigen be perceived as a self-antigen in female mice? … in male mice?
C. Considering the need for TCRs to bind to both MHC and the antigen, indicate for each
transgenic mouse in the table below if it would (+) or would not (-) have immature doublepositive and mature CD8+ thymocytes bearing the anti-H-Y T-cell receptor.
Transgenic
mouse
DP
thymocytes
SP CD8+
thymocytes
H-2k female
H-2k male
H-2d female
H-2d male
8. Gene ‘knockout’ can be used to prevent an organism from producing a specific protein. Knocking
out either MHC-I or MHC-II expression interferes with the ability of the thymus to produce TH or Tc
cells. Explain why each of the following answers is correct or incorrect.
A. T-cells must also produce MHC proteins on their membranes to function.
B. Binding to MHC proteins is necessary for a CD4— CD8— thymocyte to develop into a
CD4+CD8+ thymocyte.
C. Binding to MHC-I or MHC-II is necessary for selection of MHC-restricted TCRs
Biol 430
Question Bank
TCRs and T-cells
Page 3
9. The figure to the right shows the design and results of the
Zinkernagel et al. experiment demonstrating the role of the
thymus in selecting for MHC-restriction of T-cells. In the
experiment, the thymus of an H-2a/b mouse was removed and
replaced with the thymus of either an H-2a or H-2b mouse.
Before transplantation, x-irradiation of the thymectomized
mouse and the new thymus was performed to kill remaining
hematopoietic stem cells. After transplantation, the immune
system was reconstituted with injection of H-2a/b bone
marrow cells. Answer the following questions with reference
to T-cell selection processes in the thymus:
A. Will the haplotype of the thymus affect the MHCrestriction of the mature-T-cells (i.e., the haplotype of
MHC to which the T-cells can bind)? Explain.
B. Assuming that ‘a’ and ‘b’ type MHC can present a similar array of peptides, will the haplotype
of the thymus affect the self-tolerance of the mature-T-cells? Explain.
Later, the chimeric mouse was infected with the LCM virus. After allowing time for the immune
response to the LCM virus, CTL cells from the spleen were tested for their ability to kill LCMinfected cells from H-2a and H-2b strains.
C. Based upon the results shown in the figure, what was the haplotype of the thymus that was
transplanted?
A. H-2a
C. H-2b
B. H-2a/b
Explain.
Biol 430
D. either H-2a or H-2b
Question Bank
TCRs and T-cells
Page 4
10. Working with fluorescently labeled antibodies against CD4 and CD8, you
perform a FACS analysis of T-cells from the thymus and lymph nodes of normal
and RAG-1 knockout mice.
A. In the diagram to the right, indicate which stage of T-cell development
will be blocked by the RAG-1 mutation.
B. In which organ will this mutation have its effect?
C. Using the diagrams below, draw FACS plots that you would expect for
lymphocytes isolated from the thymus and the lymph nodes.
Thymus
Lymph node
Hint
Cells lacking both CD4 and
CD8 will appear in the
lower left-hand quadrant;
those expressing both
markers will appear in the
upper right-hand column.
Question is adapted from
Goldsby, et al. 2003. Immunology
5th ed., Chapter 10
11. Suppose instead of knocking out RAG-1, you knock out either MHC-I or MHC-II. In the
following table, mark ‘+’ if the knockout mice will produce the thymocyte or T-cell, or mark ‘--‘ if it
cannot. Explain your answers.
Thymocyte or
Knockout mice unable to express:
T-cell that is:
MHC-II
MHC-I
CD4 CD8
CD4+ CD8+
CD4+
CD8+
Biol 430
Question Bank
TCRs and T-cells
Page 5
12. Crohn's disease (CD) is a gastrointestinal disorder characterized by areas of inflammation
separated by areas of normal lining. In the active condition, mucosal inflammation can lead to
ulceration of the intestinal wall, although periods of remission are quite common. Symptoms of
Crohn's disease vary among afflicted individuals, but include abdominal pain and cramping, diarrhea,
need for frequent bowel movement, nausea and vomiting. The disease is believed to be an autoimmune
disorder. In a recent investigation Saruta et al. examined the association of Treg cells (CD25+/FoxP3+)
with the disease.
Through biopsy and colonoscopy,
lymphocytes were obtained from normal
individuals and patients with active and
inactive Crohn’s, and the number of
CD25+/FoxP3+ cells was determined.
Results from three representative
patients are shown to the right.
A. Briefly summarize the
methodology used to create the
plots in this figure.
B. In which quadrant of the plots do Treg cells appear? Explain.
The relative numbers of Treg cells compiled for
all patients are shown in the next figure. Note
that each patient is represented by a single point
and averages as a horizontal bar.
C. Explain the structure of this graph; why
are the data points aligned in columns.
D. Rank the groups from lowest (1) to highest (3) Treg levels. Are the results significantly
different?
E. Offer an explanation for the relationship between relative numbers of Treg cells and active vs
inactive CD.
Biol 430
Question Bank
TCRs and T-cells
Page 6
Location of FoxP3+ cells was also examined in different
intestinal tissues, such as mesenteric lymph nodes (next
figure) showing follicles (F) and paracortex (P); FoxP3+
cells are stained brown.
F. What methodology was used to create this image.
G. In which part of the lymph node are FoxP3+ cells
most abundant?
H. Does the location of FoxP3+ cells correspond with your expectations in light of the functions of
the paracortex and follicles? Explain.
Saruta M, Yua Q, Fleshner P, Mantel P-Y, Schmidt-Weber C. 2007. Characterization of FOXP3+CD4+ regulatory T cells
in Crohn's disease. Clinical Immunology 125: 281–290.
Biol 430
Question Bank
TCRs and T-cells
Page 7