PCB 3233
PCB 3233 Exam 4 Study Guide 2026
start of chapter 7
Where does T-cell maturation take place?
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?
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?
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?
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?
PCB 3233
, PCB 3233
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?
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)
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?
a. T cells that express the αβ TCR but do not express CD4/CD8/NK cell markers.
This happens when the progenitor T cell expresses T-cell specific adhesion
molecule CD2 and other molecules but not TCR complex.
i) CD2 and CD5 are expressed. CD4 and CD8 are not expressed.
ii) Notch 1 keeps the T-cell on the T-cell path.
b. T cells that express both CD4 and CD8.
i) CD2, CD5, CD4, and CD8 are being expressed.
The two T-cell lineages: α:β and γ:δ
a. Which is considered to be the majority and which is the minority?
b. Do the loci lineages derive from a common DN or DP thymocyte precursor?
PCB 3233
PCB 3233 Exam 4 Study Guide 2026
start of chapter 7
Where does T-cell maturation take place?
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?
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?
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?
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?
PCB 3233
, PCB 3233
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?
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)
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?
a. T cells that express the αβ TCR but do not express CD4/CD8/NK cell markers.
This happens when the progenitor T cell expresses T-cell specific adhesion
molecule CD2 and other molecules but not TCR complex.
i) CD2 and CD5 are expressed. CD4 and CD8 are not expressed.
ii) Notch 1 keeps the T-cell on the T-cell path.
b. T cells that express both CD4 and CD8.
i) CD2, CD5, CD4, and CD8 are being expressed.
The two T-cell lineages: α:β and γ:δ
a. Which is considered to be the majority and which is the minority?
b. Do the loci lineages derive from a common DN or DP thymocyte precursor?
PCB 3233
