PCB 3233 Exam 4 Study Guide with
Complete Solutions
start of chapter 7
Where does T-cell maturation take place? - Answer️️ -T-cell
maturation takes place in the thymus
Be able to understand some similarities and differences between B
cell and T cell development.
a. Examples: Where do the...
PCB 3233 Exam 4 Study Guide with
Complete Solutions
start of chapter 7
Where does T-cell maturation take place? - Answer✔️✔️-T-cell
maturation takes place in the thymus
Be able to understand some similarities and differences between B
cell and T cell development.
a. Examples: Where do they derive? What cellular mechanisms or
processes are shared between the two? What comprises their cell
lineages? - Answer✔️✔️-Both B-cells and T-cells derive from the bone
marrow stem cells but the T-cell moves to the thymus to mature
while the B-cell stays in the bone marrow. Both undergo gene
rearrangement which produces antigen receptors. T cells have two
lineages.
Regarding the initial stages of T-cell maturation, explain the
direction of its migration using "subcapsular region", "medulla", and
"cortex" as references in your description. Where would you expect
to find macrophages? What about dendritic cells? - Answer✔️✔️-As
the T-cell matures, it migrates from the subcapsular region of the
thymus to the inner cortex and to the medulla. Macrophages are
found in both the cortex and the medulla. Dendritic cells are found
in the medulla.
In the thymus, what is the role of macrophages? Where are Hassal's
corpuscles found? - Answer✔️✔️-Macrophages remove the
thymocytes that do not mature properly. Hassal's corpuscles is
found in the medulla of the thymus and it induces the development
of regulatory T cells.
Evident from patient's who demonstrate DiGeorge's syndrome, the
development of a functional T-cell repertoire is crucial to an
individual's health. What causes DiGeorge's syndrome? Know the
chromosome affected. Identify what is NOT being produced in this
clinical condition, and what further consequences are associated.
Can DiGeorge's syndrome be cured? - Answer✔️✔️-DiGeorge's
syndrome is caused by a deletion in chromosome 22 where the
thymus fails to develop and T cells are absent. The lack of T cells
and thymus increases susceptibility to a wide range of
opportunistic infections and it resembles SCID (severe combined
immunodeficiency disease). Cannot be cured.
The thymus is considered to be completely developed before birth.
However, its deterioration results with natural aging, indicating that
the younger you are, the more active it is. Knowing this, would you
expect T-cell immunity to become defective overtime? Why or why
not? What about in the case of a thymectomy (removal of thymus);
would you expect impairment then? - Answer✔️✔️-T-cell immunity
does not become defective over age. The thymus just does not
develop as many T-cells over time. T-cells stay in circulation for
several years. T-cells do not become defective even after a
thymectomy.
How does the life of a T cell differ from that of a B cell? Which lives
longer and why do you think that is? (Hint: understand what "self
renewing" means in this context) - Answer✔️✔️-T cells are long-lived
and self-renewing. T cells are in circulation in the blood stream for
several months. Self-renewing cells divide to maintain the amount
of cells.
Double-Negative (DN) thymocytes vs. Double-Positive (DP)
thymocytes:
a. When/why are they called DN thymocytes?
i) What cell-surface proteins are expressed? Which are NOT being
expressed?
ii) What is the importance of Notch 1 for these thymocytes?
b. When/why are they called DP thymocytes?
i) What cell-surface proteins are being expressed at this point? -
Answer✔️✔️-a. T cells that express the αβ TCR but do not express
CD4/CD8/NK cell markers. This happens when the progenitor T
3
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